East and West are Subject to Wandering
Archæologists have discovered that it is not just modern mankind that buries its dead with their feet to the east, it has been going on for a long time and in a lot of cultures. They have also noticed that all of the bones in a particular ancient burial ground are buried in more of a loose version of east or sort of east, rather than on a true line. The reason, they conclude, is that the sun is on a different arc at different times of year, so folks got buried according to where the sun was at the time. The ancient ones didn’t have smart phones with a compass app.
I spend a lot of time with archæologists and never really thought much about that business of a wandering east and west until I got serious about solar. The airstrip at my farm heads east-west along a section line and I just sort of expected the sun to rise at one end and set at the other when I installed my panels on the northern edge. Sometimes it does. Right now it rises over the blacksmith shop, which is more east-north-east than east. Early in the morning, instead of those first rays hitting my panels and filling my starving batteries, they are lighting up the backside of the Solar Shed! Man, that sucks. Summer is supposed to be that special solar time of the year, with its long days and high angles. Turns out, not so much.
Well, no worry, early morning sun is at low angles and doesn’t give you much power, anyway. Right? Tell that to the batteries.
If Only the Sun Flew Right Down the Runway—Look at the Offset of the Plane’s Shadow in this Afternoon Shot
Then it gets a little higher and what happens? THAT tree blocks the first two charge controller groups of sun until noon. If the sun flew right down the runway, chasing the Airtractors, all would be well. To make matters worse, the big oak has grown, moving closer to the solar shed. Yeah, I have trimmed it, but there are limits as to how high I will climb a tree with a heavy chainsaw. I’m not nearly as immortal as I used to be. The solar shed is also 65’ closer to the tree, as it, too, has grown. The crown of an oak behind the shed is growing and threatening to shade things and some pines on the west end, though well away, are catching the afternoon sun as it arcs back to the north.
The moral of the story is to put your panels well away from the trees. Even if you are a tree lover, some must die. Best that this happens before you build your array. Why don’t I cut down the trees? Murphy’s Law says that anything that can go wrong, will. Neal’s Law says that if anything goes wrong, it will go wrong on the most expensive stuff. Neal’s Corollary says if anybody has a video camera running then the first two laws are a sure bet. Go to youtube and look up videos of people cutting down trees!
There are ways of dealing with trees. The expensive way is to hire a pro tree crew to come in and take the tree down, starting from the top. This is expensive, but usually safe. Another way, and I get this idea from nature, is to just kill the tree and the limbs will start falling in small pieces, straight down until you have a manageable post. I have 3 trees I am working on now and they are taking their sweet time about dying. Take a chainsaw and “girdle” the tree by cutting all around, just through the bark and the layer that passes water and nutrients up. That didn’t work. Take a weed torch and burn the bark all around. That didn’t work. Drill a series of one inch holes around the tree and pack them with salt. That didn’t work. Super Oaks! Fill the holes and grooves with Roundup.
One of the trees is starting to look a little sick. Eventually it’ll get the job done and the trees will slowly crumble. Don’t worry, tree lovers, I’m a tree farmer and I’ll make more…just a little further away. So, the moral of the story is that you shouldn’t just kind of nestle your array in with Mother Nature, because she will try to keep the sun to herself. Plant your array clear of trees to the south, east and west and maybe just a bit to the north. Stand in the middle of where your array will be, facing south. Hold your arms straight out and bring them as far back as they’ll go. That angle back should make a pretty good template for your arc of clear space.
And don’t think that planting trees in front of your solar panels will make them twice as green, like these folks did in Japan! How well do you think this is going to work out? Photo is from Kyocera.
–Neal
Think Outside the Box
The purpose of this post is mostly to stimulate thought and open up some possibilities for you. Many folks would find these ideas impractical or even impossible if you live in an apartment or have a strict homeowners association. Wild stuff, but maybe there’s a mad scientist among you who could make it work.
If you know John Kimball, Sun Electronics’ fearless leader, he has been on a crusade for decades to bring affordable solar power to the people. As far as the PV modules go, he’s there. Solar panels are no longer the problem. I have noticed pricing on charge controllers dropping and pretty soon that will no longer be a huge part of the equation. With inverters, the problem is that there is such a flood of cheap Chinese inverters that you might be tempted to go with one of them, whereupon it is quite likely you’ll find you made a mistake and end up buying the more expensive model, too. What I am looking at as MY biggest issue in my personal solar power systems (yes, plural) is storage.
Where do you store your power? In a battery, right? Utility scale battery and electric automobiles would probably drive the price way down, but on the other hand there is a huge demand. LOTS of battery research is going on and someday someone will come up with the super cheap-but-good battery. In the meantime, there are OTHER possibilities to store energy, though not necessarily electrical energy.
Big utilities have used a couple of neat tricks over the years Hydro plants just let the water back up behind the dam, then run it through the turbines to make electricity, as needed. Some utilities not normally considered as hydro, take their excess electricity to pump water to a lake on a hill, then run it back down the hill through a turbine when they don’t have enough power from their regular supply. Some are now using pumped storage with solar, to keep the lights on at night. Now, I am thinking that this would be impractical for you and I, given the space required for a couple of lakes and a power station.
Another big utility trick is to pump air into underground caverns, using surplus power, and then letting the compressed air run a turbine to make extra power when needed. Again, that’s not going to be good for most of us. I don’t know about you, but I am pretty sure there aren’t any underground caverns where I live. This is not to say that compressed air could not be used, and in more ways than you might think. Let’s say your solar power system has your regular battery topped up for the morning and not much is running in the house, why not have it burn off the extra power from your panels by running an air compressor? For this kind of duty you’d need a pretty tough compressor, but they are out there.
You pump the air into a huge pressure tank (huge being a point of inconvenience to many), perhaps one like they use at those propane storage yards. Such a tank would be expensive, if bought new, but you can find amazing values in industrial surplus. You might find one for scrap value. When the sun goes down and the regular battery is getting low, you send the compressed air to an air motor. You may not be aware of these, but they are very common in industry and can be very durable. The air motor spins a DC generator to charge your batteries. This is dirt simple to do, but huge. Far fetched? Under the city of Paris, France, there is an abandoned network of pipes from an era where a central compressor station transmitted power to businesses all over the city, powering industry!
Google it and read THIS article. You can store a lot of power with compressed air. Even run a car!
There are side benefits to consider, too. When you compress any gas it gets hot. This is how heat pumps work. If you put your hand on the top of a running compressor then you will quickly notice it is quite hot as you pull your blistered fingers away. If you put that freshly compressed air through a heat exchanger you can heat your domestic water supply. On the reverse side of the process, when the air expands through a motor it comes out quite cool. The air can be run through a heat exchanger for storage, or exhausted directly into a room to keep it cool.
Ok, that’s pretty off the wall stuff. How about one that is so simple, even your cat understands it: thermal storage. The cat finds a spot where the sun shines through the window on a cool morning and is warm and cozy. John sells a thermal solar water heater that mounts in a sunny spot. It uses some super simple, but highly efficient technology that will do a dandy job of replacing the electricity or gas you use to heat your bath water or if you can use several of them and greater storage, you could probably do a good job of supplying water to a hydronic home heating system. You can run the hot water through pipes embedded in your slab, through baseboard heat exchangers, or through a radiator inline with your central air handler. Heating water directly from the sun bypasses the solar electric, charge controllers and batteries. Storage is just an insulated tank.
I have some other mad scientist ideas I will share with you as information is firmed up. A friend dropped off an extra pallet of solar modules and microinverters he had to use in the ongoing solar air-conditioning project. In conjunction with that, I’ll have some gear available to test some of the old wives’ tales about what you can and cannot do with certain pieces of equipment. I don’t think this will turn out quite as destructive as the time we used a 12 gauge shotgun to blow holes in a panel (it still worked), but there could be smoke.
–Neal
Microinverters!
What is a microinverter and why in the world would you want one? The first answer is easy. Whereas a regular grid-tie inverter takes the power from a bunch of panels and injects it into the powerline, a single microinverter bolts onto the back of each panel. The solar panel’s MC4 connectors plug into one side of the microinverter and a connection to the 240 ac power line plugs into the other side. This makes setting up a grid tie system very easy, though in most cases you still have to have the disconnects and special metering arrangements made with your power company. Look there’s a box full of microinverters! A company called Enphase is the big player. Their fuzzy “e” logo is very disturbing to someone like me with eye problems.
The problem I saw with them when I first looked into the matter was that each micro inverter was close to $200, or about double or triple the price of a typical solar panel from Sun Electronics. Then there was the power output. The M215, shown above, only outputs 215 watts. Hook it to a 300 watt panel and you still get 215 watts, so you are wasting some of your power at peak times. Enphase makes the argument, though, that you get more consistent power output over the course of the day. It is kind of a dubious argument, but there is some merit to it in special cases, such as a project I am currently working on. Shortcomings aside, there may be some good to come of using these. For some reason, tons of them have been dumped, brand-new-in-box, onto the open market at dirt cheap prices, like around $30. (A word of warning, though, make sure you can get the cables and beware of the price of cables! ) At that price it gets interesting, but you need to use caution. A friend drove down from South Carolina and dropped off a case of the M215s and a pallet of panels he wanted me to try. The M215 uses a lower voltage than the newer models, so he made sure he brought me a pile of 60 cell panels. Turned out they were really 96 cell panels, shipped by mistake. He had not even looked at them. I keep telling him to buy from Sun Electronics, but he doesn’t listen! The 96 cell panels put out nearly 60 volts whereas a 60 cell panel is usually around 36, open circuit. 72 and 96 panels are now the norm and I guess that is why the older microinverters are on the surplus market. All but two of those 60 cell panels are equipped with microinverters. The blue ones are 270 watts and the black ones are 300 watts.
Now I mentioned that having that controlled output could be useful. An experiment that we are running involves connecting the microinverter’s power line to the MOTOR side of the contactor in a central a/c compressor. I have 10 microinverters connected to my a/c. What happens is…nothing, until the thermostat clicks the contactor starting the a/c and connecting to the microinverters. After 5 minutes, the sync light comes on and suddenly the a/c is using very little from the powerline. Huh? Okay, here’s the deal, a grid provider does not allow grid intertie, but mixing the power from the microinverters with the power from the grid, you get to use the solar power without backfeeding to the power company. So even though we are connecting grid intertie, there is zero flow and nothing for their electronic meter to report. This, of course, assumes you have selected an amount of microinverter power that does not exceed what the a/c is consuming. Here’s a picture of the meters inside my upstairs a/c compressor. The bottom meter is the power line. Lower left corner of it shows the a/c drawing 75.2 watts. Of course, the a/c needs more than that. The middle meter shows the power actually being consumed by the compressor and the top meter shows what is coming from the microinverters.
Because the microinverters take about 5 minutes to sync with the line before providing power, you want long run cycles. This scheme works best if you use a programmable thermostat to cool like crazy during sun hours and then ride through the night on the stored cool. At the present, this project is not on the grid power line, but on my solar microgrid. Yes, the microinverter WILL sync to a good sine wave inverter! It is taking a lot of the load off of my smallish inverter and definitely letting my batteries charge up quicker during the day. If you try this with your a/c on the grid, is this going to save you a ton of money? Probably not, but it is a fun experiment. I have a few more microinverter experiments I am working on and I’ll let you in on them, soon. If you want to try some of this stuff for yourself, John’s guys can fix you up with some super deals on 60 cell modules—Neal
Power Use Optimization and Free Energy Storage
In my last post I talked about some seemingly off the wall, but doable, energy storage contrivances. As for the compressed air storage, apparently some pretty clever people have already thought about this. Follow this link to a pretty thorough discussion of the subject.
There are some pretty neat pages at Low Tech Magazine and No Tech Magazine. Speaking of energy storage and No Tech, how about storing energy with NO equipment? This is coming out of the solar air conditioning research. First, it is a no-brainer to state that your solar electric electrical system works best on a sunny day, right? Well, fact is, it doesn’t really draw in useable energy at night, even though a full moon might make the green light come on on your system. So, it makes sense to use the energy when it is being made, rather than tax the batteries so severely at night.
Here is what I am doing and it is so simple. During the day, my programmable thermostat is set to a fairly cool temperature, within the limits of what the array can supply. Usually, that is around 76 degrees. I am looking into building a smarter thermostat that will take into account the state of the battery charge and the weather, so that I can squeeze out a little more performance without being here to manually manage things. At night, the thermostat gets set to 79. Some folks could not go for that range, but as a native Southerner who grew up without a/c, no sweat. Literally. The reduced humidity of the a/c is as big a factor as the temperature on one of those hot, muggy days.
Ok, so where’s the storage? What’s the medium. Look around your house. Sheetrock walls, tile floor, pots and pans, that cast iron bathtub, brick or stone fireplace…anything and everything with some thermal mass. You’ll have the cooler temps when you are stirring about and need it cooler for comfort, but at night, when you are reading, watching the tube or sleeping, the temperature will slowly creep up as thermal mass will slowly absorb the heat seeping in. At a high in the high 70s should be fine, especially with a ceiling fan. I still have the a/c running some during the night, especially those nights, but not nearly enough to run down the battery bank.
Just leaving the thermostat at one temperature has its merits, but for using the power when you are making it, changing temps makes for longer run cycles to optimize efficiency. I know from observation that my PV is putting out enough power to run the a/c without getting into the battery about 9:30 a.m. in the summer. Having the program go into cool-down, starting then, means I can run the a/c without taking the battery down any lower and any time after that I am building power to fully recharge by the end of day. In the late afternoon, I cross that threshold again around 5 p.m. The frequent afternoon thunderstorms can play havoc with that, though, hence the quest for a smarter thermostat.
My house is powered by a hybrid system, part on and part off grid, so I still get a power bill. I suspect some of my neighbors have cooler homes than mine, but I bet they have bigger power bills, too.
—Neal
Show and Tell
I wanted to show you a couple of examples of some really nice solar work I have seen lately.
I’ve known Courtney for 60 years. Back then Courtney was a guy name and, in his case, it still is. Courtney has gone nuts for solar in the last few years and he is at it again. In addition to our joint solar a/c schemes, he decided that his curved solar pergola grid-tie is not putting out enough to suit him, so he’s adding modules. There is no more room on the pergola, but there is plenty on his north fence, which happens to be close to his grid tie gear. Between the fence and the retaining wall we built (somehow I got roped in on that) he came up with a quick and easy mount that looks good, I think. Under the panels it would be easy to integrate some sort of box for storing yard tools or such.
This is just to try out…He’s adding more.
Then there’s Daryl, to whom John introduced me a week or so ago. OMG what a system he has and what beautiful work he does! Daryl lives in a barn in Texas. No kidding, it is a Texas thing and they call them “Barndominiums.” This is neither Daryl’s first barndo nor his first solar power rodeo. Sadly, there was a fire that destroyed the first. Texas has some serious hail, so his first system actually had doors that slide on rails to protect the solar panels! The new barndo has 16kw of modules, ganged inverters and a monster battery. And it is simply elegant! It is grid-tie with battery backup and he sells more power to the grid than he uses. Here’s where the kilowatts begin
Here is where kilowatts live…in the giant BullDog battery. Moving that dawg requires mechanical assistance.
And everything has to pass through here
THREE inverters, Daryl??? Really???
Okay, I admit it. I’m jealous.—Neal Photos: Courtney and Daryl
Cool It
I never thought I’d be happy about a tropical depression starting to spin up in the Gulf, but it has been really, miserably and mind-numbingly hot around here and the rains have helped in that department. We’ve topped 100 degrees for days, usually hitting 103-105 after lunch. It has been so hot that I have been wearing welding gloves to handle modules I am remounting. Of course, inside the Solar Shed, it is even hotter and even the a/c out there is no good until I get some insulation.
Fortunately, that temp is within specs for all of my gear, but I know the fans and capacitors will last longer if I can make it run cooler. Further, since it has temperature sensing that cuts back the wattage to keep the temperature down, running cooler will put more watts back into my batteries.
I have some charge controllers I am evaluating for John to possibly carry and they have built in thermometers. The display was showing 57C, which is right at 135F for Americans. The charge controller has a fan and the entire aluminum case is designed to dissipate heat, but it was hot to the touch and the fan was always running. The thing is, the entire back, over 1/3 of the surface area, was pressed against the wooden mounting panel, effectively insulating it. Why not mount charge controllers on standoffs? A drilled piece of rod, a stack of washers or a slice of old broomstick with a hole down the middle would each make a dandy standoff. I had some aluminum heat sinks I found on ebay that may or may not do even better.
Note the fins behind the charge controllers.
I removed the old screws, smeared some silicone heat sink grease (available online or at an electronics store) on the heat sink, wedged it behind the controller and snugged down four new, longer, screws. That’s all there was to the first one, so I did the second. In no time the controllers’ internal temp dropped 14C or 25F.
I suspect that simple spacers would do about as well. This afternoon, after a thundershower, it was only 98F in The Shed and I noticed that the fans were not even running. I think I will watch this a few days and try it on the others.
If your mounting panel is metal, then you already have temperature dissipation help. For anyone else, this is a good, cheap mod. Now as to why I was arranging panels in the hot sun, it isn’t just cooling down the equipment I am working on. Nope, I am continuing the quest for solar powered a/c. Early small scale tests have shown promise (mostly meaning I haven’t started a fire) so I am making room to dedicate 8 to 11 modules to running a conventional a/c on solar with no wires going into the house and only three going into the outside cabinet. Watch for that. It may take a while to get all the details ready for you, but the mod will work in heatpump season, too.
I do have some tried and true solar a/c that I wrote about in the blog. That may have disappeared when the blog blew up, so we will try to get that reposted. I am running BOTH of my 30 year old Rheem central air systems and most of my other circuits on a single 5kw inverter, and it isn’t that hard to do. Watch for it to reappear if you can’t find it.
–Neal
RTFM!!!
RTFM!!! That stands for Read The Fine Manual. There are variants on that acronym, depending on your vocabulary.
That’s what we used to say when a customer wanted to know how to work something he bought from us, but was unwilling to read the instructions. This happens a lot with solar stuff, too. You may have products that can do more work for you, saving you from having to buy other gear. Wouldn’t you like to know stuff like that?
Case in point, I had a problem with having too much power on a sunny day with lots of puffy cumulus clouds. The charge controllers would get all settled down in the shade of the cloud, then it would pass and it’d go high enough to trip overvoltage conditions on the inverter and/or one of the charge controllers. The one charge controller would shut down until manually reset, the inverter would clear itself as soon as the other charge controllers caught up with the increased sunshine, usually just a couple of seconds. It really wasn’t a huge deal to me, but the princesses do not like to have their afternoon DVD features interrupted, not even for a few seconds.
I can think of lots of ways of dealing with this. Setting the dominant charge controllers worked out most of it, but it could still happen. A diversion load controller, like the windcharger crowd uses would be perfect, except it costs several hundred bucks for one of those. I think it is a C40 charge controller that some folks use for solar can do the same trick, but I don’t have one and don’t want to spend several hundred bucks for one of those, either. You should see a pattern here about my reluctant spending habits.
In my younger days, I’d have simply designed and built a custom controller to disconnect several banks of solar panels, putting the system on a more defensive stance. I don’t want to be bothered with that, anymore.
It turns out, though, if I just RTFM on stuff I already own, lots of gear has extra functionality built in that nobody ever uses or maybe they under use it. For example, let’s take the FlexMax family of charge controllers. If you’ve bought one of John’s kits, there’s a good chance that you have one or more of these, already. It is a popular model and built like a tank. Pop the hood and you will discover a tiny connection block that is programmable to drive a relay six ways from Sunday.
It’s the little gray terminal block marked 12v Aux Control on my revision.
This won’t do much as it is, but it will drive a 12v relay like the one that beeps the horn or rolls up the windows on your car. You can buy these, with a wired socket, at your auto parts store or Ebay. The relay, in turn, can control 30 or 40 amps of load or drive a contactor to solve my problem by disconnecting some banks of solar when the battery is charged. It can be programmed normally on, normally off, high voltage trip, low voltage trip or more, if you RTFM.
What can you do with this? Well, you can control a light to come on at night and off during the day. You can use it to enable high power loads, like a water heater or an a/c, when the battery is happy and not when it needs a little help, like on a cloudy day. Charge your electric vehicle when the main bank is good. Sound an alarm if the battery is low. Turn a fan on or off if your equipment room gets hot/cold. This thing has skills!
Study the description of the capabilities and you may think of more ways to use it. RTFM!
By: Neal Collier
Cool Running
We surely do get spoiled by some of our modern comforts, don’t we? When I was a kid, we didn’t have air conditioning at the first 3 houses in which I lived, nor at school. Our first car with a/c was a ’65 Pontiac. Although I don’t crank the thermostat down low, I still like to have it to knock down the humidity and cool down on those muggy Florida afternoons. One of the goals I have been working toward is to get the house’s central a/c on the solar. It is a big part of the power bill, so it is a good goal. I used 215 kwh from the grid this past mild month and would like to keep it close to that through the summer, instead of the 1500 kwh (or more) that my neighbors will use.
A few years ago, as an experiment, I parked Sun King (my solar launch) next to the house and ran a line from the boat’s inverter to a window a/c. It worked great, but a 5000 BTU window unit is not what you need for a two-story house. My first attempt at running the central unit on my 24 volt system almost worked, but only because I was low on freon. All charged up, I couldn’t quite get over that startup surge. It is probably just as well because I discovered that the transformer in that cheap Chinese inverter was just a wee bit underrated and would have melted running the a/c all day.
I know my 12kw inverter would have run it because it worked for the guy from whom I bought it…but lightning fried that hope. My homemade 5548 has a huge transformer and will put out thousands of watts continuously, but it still could not deal with that starting surge. I probably could have tweaked the overload settings, but it works fine, otherwise, and I did not want to break it. Should I give up? Ohhhh, no. In a case like this, we simply need to change the rules.
This surge problem doesn’t just come up when running on an inverter, campers and boaters like their a/c, too, but sometimes end up getting a really big generator to run it. My friend Courtney has a huge bus with a big, rumbly Onan generator. Run the thermostat down and that Onan acts offended when the compressor kicks on. After that first couple of seconds, the Onan settles back into its lazy rumble, but you can tell it doesn’t like the startup.
But, dig around on the internet and you’ll hear guys talking about running a one-ton or even an 18,000 BTU a/c on a Honda 2000 generator! What? I can’t run an 18,000 BTU a/c on a 5500 watt inverter, but they can run on a 2000 watt Honda? Let me give you a hint: they cheat. They changed the rules.
If you are looking to install a new a/c, one of these new-fangled inverter mini-split rigs might be the way to go. When they say “inverter” they mean a variable speed motor controller. A few makers put inverter compressors on full size systems, too. If you’ve not seen these, or paid attention, these units start the motors up slowly and run just fast enough to maintain the temperature you set. It really is hard to tell the things are running! In addition to eliminating the starting surge, you may end up using half as much power in the long run with units up to a SEER 25 rating. For comparison, my 30 year old unit is a “High Efficiency SEER 13” model. You’ve seen the TV commercial with the old a/c unit quivering, rattling and giving off a puff of smoke? That’s mine.
Yeah, but if you are like me and are not too keen on spending 6 grand to replace something that still works and will run on FREE electricity (assuming I can get it to run at all) you may want to “cheat” like those campers and boaters are. You see, there is a thing called a “soft start” that emulates the slow spinup that the inverter units use. They sell under the trademark names of Dometic SmartStart and Hyper Engineering Sure Start. They aren’t cheap, listing around $600, but you can shop around. I found a couple for my units for $100 each from a marine salvage dealer. Buying something used without documentation may not be something you’d feel comfortable installing yourself, so you might hire that job out or get your HVAC dealer to come up with one.
Changing the Rules: SmartStart on my A/C
When the time came to give it a try, one of the golf cars was charging and the refrigerator was in auto-defrost mode, so there was already a good load on the inverter. I ran down the thermostat and the lights gave 3 little flickers as things began to run. The starter has a microprocessor that learns the load and afterward the startup was so gentle you had to watch for any flicker at all. I would say it dims the lights less with everything on the solar power than it did when everything was on grid, without the starter. Once underway, the compressor is pulling maybe 1800 watts and plugging in the golf car or firing up the Keurig while the princesses are watching Disney in the living room still leaves power to spare. The one unit upstairs will cool the whole house, but I will go ahead and convert the downstairs a/c, too, when I get the 10kw inverter built.
What about nighttime? I do not have enough battery to run a lot at night, but I have a plan. Using the programmable thermostat, I will really cool down the house during the day. When you are active, a little cooler feels good, anyway. Then, late in the afternoon, I’ll run the thermostat up a few degrees. The thermal mass of the drywall will hold that cool for quite a while, maybe even until morning, if it isn’t just awfully hot. I have no doubt the average house temp will be cooler than it has been when I was paying for those overpriced kilowatts from my power co-op.
So, success at last! The only problem is we have a cold spell for the next week or so and I don’t need a/c! That’s ok, the heat will come, eventually, and I will be ready. What about you? Are you up for getting a little more comfort out of your solar power?By: Neal Collier
Battery safety tips
Bring a big truck when you visit and work safe when you get home.I write this stuff for fun and to be helpful. I’m not an employee of Sun Electronics, I’m a customer. In my role as customer, I set out the other afternoon for my third visit to Sun’s Miami headquarters and my first visit to the Miami Lakes facility. This place is a lot nicer than the Miami Gardens warehouse, though it lacks the artistic touch left at the old place by some tag artists.
It is a round trip of 1482 miles for me, so I like to make a good haul of it. I brought my big trailer. We stacked panels until the fenders rested on the tires and I made the decision to leave two pallets behind. 14kw will keep me busy for a while, anyway. I also didn’t get as many batteries as I wanted. Upon calculation back home, I figure I brought home close to 6000 lbs. I could have carried that extra stuff, after all! We just needed to pry the fenders up a little further off the tires.
Live and learn.
Well, back home, I had some ideas how I was going to treat the batteries on my new 48v system a little differently. I like to improve safety and efficiency as I go. I know ways of doing it wrong, both from investigation and from practical experience. One of the easiest ways of blowing up some batteries is to hook them up backwards. The things are marked plus and minus and we all know not to mess up the connections, but you get tired, the area may not be well lit and the batteries may have some dust or baking soda on them to obscure the markings molded into the cases. Furthermore, those pesky cables get in the way! Believe me, you CAN hook them up wrong and I HAVE done it and didn’t like how it worked out.
First thing I did before taking them off the tailgate was to hit the POSITIVE corners with a dash of white paint. I thought about red but Trojan batteries are sort of red, so I think the white will stand out better, even in poor light. White on the black Sun batteries will not be confused.
After the paint dried, I used a felt marker to put the date, 11-18, on the white patch. Time gets by, you know. If you don’t date them, 8 years from now you’ll be wondering why those batteries you JUST BOUGHT aren’t holding a charge like they used to. My Dad dated every tool and appliance he bought and I have decided it is a good idea.
Next step is to get out a little tub of grease, or maybe get into the grease gun you use for the pickup. The area where the lead terminal pokes through the plastic case should be sealed, but you will always find one or two that eventually leak acid fumes and make green stuff corrode your nice battery cables. Take the grease and smear it around that transition from lead to plastic. Then save some to coat the terminals when you get your cables connected.
And speaking of terminals, why not make new battery cables for your new batteries? I checked and found I have a good supply of double-ought (2/0) cable and around 30 big, tinned terminals for 5/32″ studs. That’s probably overkill, but I am good to go. I need to order a bit of marine shrink tube.
Some people crimp with a tool that looks like a bolt cutter with dull jaws. I have a couple of tools that look like little presses. You put the terminal on the wire, poke it between the jaws and beat the heck out of it with a big hammer. For even less resistance, I then heat the terminal with a torch and slip some solder inside. I finish by covering the transition from wire to terminal with marine shrink tubing. This is available in red or black, coding + and -, and it has an inner lining of melty glue like you get from a glue gun. You shrink that stuff down with a heat gun or torch (if you are careful) and nothing is getting in. AND the color gives you a surefire coding for polarity.
Why is polarity so important? If you try to connect two banks of batteries in parallel and do it backward you will blow yourself up. Usually the cases don’t blow apart, but everything gets sprayed with acid and your battery caps get ruined if they are the push-and-twist variety. If you blow up a set of the expensive water saver caps you will be especially displeased with yourself. If you aren’t wearing your safety glasses you can be blinded. Your hearing might be damaged. Your clothes will need to be replaced, even if you wear a protective apron. Don’t blow up your batteries.
That’s hooking batteries up backwards. What if you get the battery banks right and then connect backwards to your charge controller or inverter? If you bought hardware with “reverse polarity protection” then nothing will happen. NOTHING. If not, there will be a spark, a puff of smoke and you just trashed a $500 charge controller or a $5000 inverter!
The synopsis of all this is that it is best to hook the batteries up right and any trick you can come up with to help you avoid a mistake is smart procedure. So, wear your safety gear (goggles, gloves, apron), color code your batteries and cables and check your work with a meter before making the connection.
Something else to consider is that some things will give you a spark, even when you do connect it right. Charge controllers and inverters have big capacitors that will draw a huge quick current as they charge when you connect. If you connect to a battery post the pop may ruin the threads and I don’t think you will have a lot of luck rethreading that stainless stud. Make a quick jab at a place that is not threaded on a battery or equipment connection. Let it get the pop out of its system and then slip on the terminal and the nut. Oh, and making that pop on the battery ends of things is making a spark near a source of hydrogen gas, so best to do your sparking elsewhere. I have a big knife switch that lets me disconnect all the charge controllers when connecting the battery bank and I just slip the fuse out of the inverter.
And, hey, next time you see some of those nice LED shop lights on sale, get one to put over the batteries to make it easier and safer to hook up, tighten up and water up when installing or doing maintenance. More battery ideas next time.
By: Neal Collier
Sharing Resources
In my last post I mentioned that I had gotten carried away at Sun Electronics’ Miami warehouse and had filled my trailer and truck to the point that I decided to leave some batteries behind. I shredded one tire at one A.M. and only had one spare, so maybe that was good that I didn’t try to overdo it. Will I have enough battery power to get by until my next trip to Miami? Probably, yes. You see, I have figured out how to incorporate some other battery sources that I already own. Many of you may be able to do the same.
Before I explain, I’d like to introduce you to the Anderson plug. If you have ever noticed how a forklift battery plugs into the lift truck or the charger, well that’s an Anderson plug. It is a flat, two pin plug that is polarized. One plugs into another, they are both the same and you can’t plug them in backwards, which is a neat trick. They come in at least 3 different sizes. There is a small one like on my niece’s ride-on electric car, a big one used on forklifts (350 amps) and a medium one (175 amps). Moreover, they come in colors, but not to make them pretty.At my house, I have gray, yellow and blue in the 175 amp size. Each color has a slight change to the shape, so you can only plug into the same color.
The first I ever used was gray, and I have one on the front of my truck. I replaced the two tow hooks on the front with receiver hitches, so I could slide a winch on and off, as needed., and plug in to the Anderson plug. I also have a 3kw inverter I can mount there for power in the boonies. Gray became my 12v standard.My solar-powered expedition boat has yellow connectors and I can plug it into the 24v system that powers my house at this time, adding an extra 350 a.h. of battery, without buying more batteries. For some reason, I haven’t had the boat out all year, yet it’s batteries stay active and contribute at no additional cost.The new 48v system has blue Anderson plugs.
There is no way I can screw up and connect the 3 different system voltage levels to each other. I have two 48v golf car/utility vehicles that can plug in to the blue line and add 350 a.h. to the 48v system. I got to considering it, and since the boat has two banks of 24v, I can use a special 3 connector cable to change them to another 175 a.h. at 48v. No screwups will be possible when reconfiguring, connecting or disconnecting and I get bunches of additional storage from batteries I already own.
A similar adapter cable could be used to connect a golf car to the 24v system without making smoke and sparks.The utility golf cars, little trucks actually, allow me to move my solar power around. I no longer even own a functioning gas generator. I cut my firewood with an electric chainsaw, trim trees with an electric pole saw, trim my hedge without a long extension cord and operate power tools for construction and repairs around my farm. The inverter plugs into the blue Anderson plug. There is also a homebrew stick welder to plug into the blue plug. Why limit your solar power to the house?
Photos that somehow disappeared: Blue Anderson plug and 3kw inverter on the solar jalopy. Solar-charged Yamaha G19 powers the chainsaw to cut wood and then hauls it to the house. They both add to the storage of the solar power system. Use your imagination until I can find the right photos and get them back here. It will be less confusing than looking at a boat labelled golf car and a bunch of flamingos labelled Anderson plug!
But back to the main topics, Anderson plugs, once successfully set up, allow you to do all kinds of configuration changes without worry about connecting something wrong. Using them to add underutilized resources to your system can help you get more out of your system without buying more.In my 48v system, with what I have, it tallies up to 460a.h. of main system battery plus 525a.h. of battery that otherwise wasn’t doing anything at night. That’s 47 kwh, good for several cloudy days.Don’t overlook what you already have!By: Neal Collier
It Ain’t Rocket Surgery
How hard is solar power? Some folks are a little intimidated because they don’t know anything about it. John has asked me to put together a booklet for do-it-yourselfers and I think that is a good idea. It just requires a little more focus than writing down whatever pops into my head. Today, though, I am going to write down whatever pops into my head AND give you an idea of how simple solar can be.
Years ago I built a playhouse for my young ward Alexia. She has about outgrown the thing, but still likes to go out there for solitude (away from her sister) or crafting. In the summer, it can get hot, so I found a small 12v panel and a small fan, the kind you can put on the dash of your pickup truck to stir up a breeze. No batteries and no controllers. She saw that if you hook the red wires together and the black wires together it blows air out the front and if you reverse the wires it blows air out the back. The only hitch is that the sun has to be on the panel and not blocked by the trees. There are lots of trees. We’ll probably get around to a more elaborate system with some old batteries when we enlarge the playhouse, so the fan will run better and she can have lights on these afternoons that get dark early.
I have a backup water pump that uses a similar setup. A couple of hundred watts of PV panels are mounted to a simple rack of 2x4s and 4×4 posts and a cable runs down to the spring where the pump is located. There is no battery. If the sun is shining the pump runs. Lots of farmers use similar rigs to water their cattle.
It sounds simple because it is.
Well, a while back I was working on a project out in the hot sun, making another modification to one of the golf car/farm trucks, and Alexia decided she was going to help. She ran to the playhouse and got the 12v fan and got a block of 4 small panels that were leaning against a tree. She used a screw gun to mount the fan on a post near my work and twisted the wires to connect solar panels to the fan. Voila! Instant relief from the heat. And a 10 year old did it, remembering what she had learned a year or two before!
Solar just isn’t that hard with a little guidance. I’ll try to help with that by getting started on that brochure.
By: Neal Collier
Solar and Taxes
The state has a pretty dismal record on solar promotion and subsidies. I didn’t even know there was a program until I read about it in a California magazine! The first couple of years, it appeared that most of the program’s budget was spent on office furniture and administration, leaving only a few slots for participants. Then the rules were a bit too burdensome to make it worth the bother, in my opinion. Maybe this has changed, in later times, but I went my own way.
The good news, though, is that there are some pretty good tax provisions to help out a Florida homeowner with solar power!
First, there is no sales tax on your solar hardware. To enjoy this benefit, though, you need to deal with a solar dealer, like Sun Electronics, because other outlets may not know about or comply with the provision. Case in point, you need a set of batteries. If you go to your local Walmart or Sam’s Club, it sure is convenient to buy their heavy duty EGC2 batteries. BUT, you can argue until you are blue in the face and they will charge you a core charge, disposal fee and sales tax, in addition to a higher unit cost. You’ll end up spending at least 50 bucks more for each battery. At that rate, you can order the Sun 230 batteries from Sun Electronics and have them trucked to your town and still save money. The batteries are rated a little higher than the EGC2, as well.
Second, if you spend 10 grand to add a nice solar system to your house, the property appraiser, by law, cannot add 10 grand to your taxable property value. Sweet.
For those of you in the other 49 states and various territories, you can check with your state’s official website for tax breaks and solar promotion programs. You may find it easier to find the info by doing an internet search for websites that have listings of such things for all states.
Don’t forget to save your receipts and go for the Federal tax rebates, too! The forms are pretty simple.
By: Neal Collier
30% More
Once you get your first taste of solar power, you want more. You can always find ways to use it. Want 30% more?
Back in the 70s and 80s, when solar modules cost a lot more in dollars and dollars were worth a lot more, equipment choices were far more limited and people were always trying to get more power from their solar panels. Makes sense.
Naturally, if you point your solar panel dead-on at the sun you get the most power, so folks came up with schemes to make the panels point right at the sun automatically! Sounds like a good idea, right? It is pretty easy to do with sensors and motors, but that uses some of the power the panel makes. My former business partner built one for one of his modules, just for fun, and it works fine. A really clever fellow came up with one that has a jug of freon on either side of a panel rack. If the sun peeks around to the west side, the west bottle warms up and the east bottle cools down. The pressure difference can drive a cylinder and the panels are caused to lean a little more to the west, and so on for the rest of the day. Next morning it all leans over to the west. It may sound complicated, but is super simple. The upshot is that by tracking the sun you can get about 30% more power from the panels you already own.
Is it a good idea, though? Well, 30% more power is, sure, but overall? First of all, all the panels and the rack are on a single pole, so it has to be a heckuva pole with lots of concrete to hold it in place. In places, like any coastal zone exposed to hurricanes, it may not be rated highly enough to stand up to the wind. One strike. I priced one tracker and it was over $6000, on sale. Two strikes.
Let’s say you have a fixed-mount 3kw PV array. 30% more is about a kw or about 3 more panels. That costs just over $300 at Sun Electronics. Strike three for the tracker! Maybe you don’t have room for 3 more panels, but want that 30% more power. There’s something for that, too. It is called a Maximum Power Point Tracking (MPPT) charge controller. It costs a bit more than an ordinary charge controller, but it allows the panels to operate at their best output voltage. (I notice that the kits Sun Electronics puts together have MPPT controllers, the good ones.) Here’s how it works. We’ve had rain for the last four days, so my batteries on the 24v system are a little depleted. Let’s say they are at 24 volts and a panel is attached and putting out 8 amps. That current, the amps, is pretty much constant. At 24 volts, those 8 amps will give me 192 watts. With an MPPT controller, though, the panel can operate at its best power voltage (you’ll find that on a label on the back of the panel) of, say, 34 volts. 8 amps at 34 volts yields 272 watts or 41% more at peak time! There are some variables and losses to consider, but you can still figure on around 30% more when all is said and done.
And you didn’t spend thousands of dollars!
Here’s one more way to save with an MPPT controller. If you have a 12 volt system, for cabin or boat, for example, you can use 24 volt modules. How does that help? Look at Sun’s price lists and you will see that 24 volt panels cost about half as much, per watt, as 12volt panels! Maybe even a third as much. Yes, you can use 24 volt panels, even in series, to charge a 12 volt battery bank and save money!
I like the FlexMax series of controllers. They are built like a tank, have all sorts of metering data for display and don’t blow up if you connect too many panels. The FM60 and FM80 are solid gear for a serious system.
Take some of the money you saved by not buying the tracker and buy an MPPT charge controller, some more panels and batteries from Sun Electronics. You’ll revel in your awesome newfound power and still have enough money left over for a nice vacation or to catch up on those pesky bills.
By: Neal Collier
Pelicans
Just a letter to John that somehow got posted here!
I’m glad to hear you are back in the water. Sounds great. Somehow I didn’t get to the water all year. Now it is too cold to stay out on the boat overnight.I like pelicans, too, from a distance. It is funny how they almost always travel in squadrons. 8 or 10 of them will sit on a floating log or do a fly-by. Sometimes you see solos sitting on a navigation marker or an old piling and sometimes you’ll see a busted up dock with dozens of them. Out in the Gulf of Mexico there are some large channel marker structures that look like pelican storage units or maybe condos. UWF has a dive barge over a 1559 Spanish shipwreck. First duty after a hiatus is to fire up the dredge pump to wash the thick, foul layer of pelican crap off the deck. OMG that stinks!
In Mobile Bay, I saw a little tern land on a pelican’s back to try to steal food scraps. The pelican was having none of that and snapped at the little guy! If you are in a solar-powered boat, though, you yell at pelicans and wave a life jacket. Pelicans look at a solar boat and think, “aircraft carrier.” No way you want pelicans doing to all those solar panels what they do to the dive barge!
The range of pelicans amazed me. I thought they were coastal birds. Not so, they go where there are water and fish. I saw them on the Mississippi River in Illinois, of all places! I don’t remember them in Pensacola, as a kid, but now they are everywhere, as are gaudily decorated pelican statues, in downtown. Somehow the pelican has become the town bird. Enjoy the art show. By:Neal Collier
Solar Heat
When my grandfather came to this country over 100 years ago, he worked his way around the US and Canada learning English and looking for just the right spot to establish a farm. About 1920, or so, he found the right spot on the shore of Lake Okeechobee, in Palm Beach County, Florida. It was heaven for a Danish farmer, with a climate that allowed year-round crops. Solar power was already a big deal in South Florida back then, even before John started Sun Electronics!You think I’m making this up? I’m not, but I’m not talking about solar electricity, either. I am talking about solar water heating and it was a big deal in Florida. In the late 1800s, a guy in Baltimore, MD, invented the self-contained Climax Water Heater. It first caught on around Baltimore, as you might expect, but was a hit in Florida. Why? My best guess is that South Florida has plenty of sunshine and, in those days, was very cut off from the rest of the country, causing fuel to be expensive. Until Mr. Flagler’s railroad, a ship was the best way of getting to the budding paradise.A Climax Solar Water Heater cost around $25, back when that was some real money.
Solar water heating kind of fell by the wayside at some point as gas and electricity became common, but guess what I saw in the Sun Electronics warehouse when I visited a few weeks ago? Solar water heaters! They are a lot more sophisticated and efficient than the early ones, using heat pipes and evacuated glass tube technology. They look kind of like this.
The tank is stainless steel with a thick foam insulation layer. Those blue tubes are magic! Not really, but they work like magic, pulling in the heat. Sure, you could use one of these babies on your suburban home to save on the power bill, but imagine the luxury of hot showers at your remote cabin or house in the boonies or on your own personal island. A remote abode would have you in pretty much the same situation as old Coral Gables when you couldn’t just call the propane truck to stop by and top up the big gas tank to fuel a water heater. I also saw solar ovens in the warehouse. Most of us would probably think of these as a novelty and only use them for camping, but I am thinking they’d be handy in case of an emergency, like for those folks camping out at Mexico Beach, where their houses used to be. There are places around the world where peoples’ health is ruined by the smoke of cooking fires. I bet they’d love one of these. The real surprise on the water heater, though, is the price. Sun’s prices are about half what some other places charge, just like with their solar panels. I wanted to figure how that compares to the prices a century ago when they paid in silver dollars. Looks to me to be about the same, now, as buying 25 Silver Eagle coins, even though the modern heaters are more efficient and durable! Solar thermal power has been put to use for a long time. Even Mom’s old black cat sits in the window of the sun porch and uses it. Why not us? By: Neal Collier
Efficiency
Going through my morning email newsletters, I came across a press release from a company called LONGi, announcing a new record of solar module output efficiency of 20.41 percent! The exclamation mark was theirs, because another tenth of a percent doesn’t get me all that excited. Last week some outfit announced their record output of over 40 percent. A close read of that announcement showed that their output was achieved with concentrating lenses. Concentrating lenses in turn require that extra effort must be made in getting stuff pointed straight at the sun or everything goes to pot in a hurry.
Any solar module will output more electricity if you put more light on it. The problem is that in addition to the extra complications and power, you get extra heat. Some years ago somebody was selling used panels from a concentrating solar farm and they looked like trays of fresh-baked cookies, all warm and brown.
Sure, somebody with special limitations on weight or available space may benefit from superduper efficient panels, but you can count on special panels having a special price. For my solar boat, the standard “B” modules I used were cheap, but heavy. I compensated by just making the roof a little lower instead of spending way more for lighter modules and the boat has so far stayed right side up. Always have the bottom of the boat heavier than the top!
If you have the space, though, the real efficiency in a solar power system is how many watts you can get for your dollars. More solar sellers seem to be using that criteria in their advertising nowadays, showing a price in $/W. This is seems to be a trend that John started with Sun Electronics, as I have always seen his panels priced that way.
Many of the panels in my array are, shall we say, not “Grade A” and I am happy if they put out anything close to the label rating, regardless of theoretical efficiency. I’m building power levels by shear quantity of modules, counting my efficiency in pennies per watt. As for improving efficiency, blowing the fallen oak leaves off the array helps and it would probably be a good idea to break out the long-handled scrub mop every now and then… it helps!
So, if your idea of efficiency is getting the most for your money, give the Sun Electronics crew a call. They almost always have deals that are even better than the published prices.
By: Neal Collier
Backup Power System, Part 3
I have been rambling about backup power and it is time to touch on the batteries and other topics. My advice on backup batteries is a little different than for solar systems. I advise that you get something that requires little or no maintenance. The reason for that is that you will probably lose interest in a system that just sits there doing nothing when the power company is doing there job, because the lights are usually on! Out of sight, out of mind. If you have flooded batteries (as I did) tucked away in an obscure place (as mine were) then it is quite likely that you will get lax about monthly waterings (as I did). If you don’t water flooded batteries, they lose power and start to emit acid fumes. Acid fumes eat up your terminals and battery racks and cause circumstances that are a lot more unpleasant than simply adding water.
SO, the best advice I can give is to use some sealed batteries, like AGM or some of those new-fangled lithiums. John has both kinds. You’ll find that AGM costs twice as much as golf car batteries and lithium…OMG. Well, that’s upfront costs. It may well wash in the long run. If the charging system is set up right, the AGMs can last twice as long. Lithiums last a lot longer and you can draw them down further without hurting them. That means a little lithium will keep the lights on as long as a bigger lead-acid model of same amp-hour rating.
There are all kinds of batteries out there, but these are the big players, the likely suspects. Just make sure you DON’T overcharge the AGMs and DO have a good battery management system (BMS) on the lithium. BMS is often built into the batteries and sometime come as a bolt-on.
Now, on another subject, did you get the Sun Electronics Christmas Eve email blast? You guys really need to read those things, even if John doesn’t make it easy. It was just a list of part number, quantity available and price. No real description. I got around to reading it Christmas day and decided to use the Miracle of Google to decipher some of these things. HOLY COW! I found that the listing “Outback PS1-3000” was a package that would allow you battery backup, grid-tie or the bones of a complete solar system. Charge controller, grid tie/hybrid inverter, breakers, surge protection, battery box, network control and more in one nice package you can bolt to the wall. They sold before I got to them because the price was $500 for a $5000 package!!! READ YOUR EMAILS!!! Somebody did and got all 3 of them.
Now, on the PS1-3000 package, this has been discontinued because there are some new rules about rapid shutdown. Outback came out with a new system that is similar, but has the rapid shutdown built in. Roberto, or one of the other salesmen, can give you the model number and price if you are interested in a package deal from a good maker.
That’s all for today. Next time is a time of soul searching and self-evaluation when I try to answer the question, “Can I install a solar power system myself?”
By: Neal Collier
Backup Power System, Part 2
Continuing on the subject of a backup power supply for your house, I want to discuss the inverters a little more. There are things to look for and things to watch out for!
I have owned lots of inverters, ranging from 150 watts to 12,000 watts. Some were high end and some were junk. I have even built my own inverters like the 5548 that is on my 48v system and a 3648 for the electric jalopy. In inverter parlance, the “55” in 5548 means 5500 watts and “48” means 48 volts. Given my Scottish ancestry, I am always looking for a bargain, but I have enough experience with this stuff that I can tell you that the ones with the higher price tags may be the better bargains.
One thing you will see in inverter specs is the type of waveform the unit outputs. The power from the power company is a sine or sinusoidal waveform. If you don’t know what that means you can look up a photo on the internet. It is very smooth. All of your equipment likes it. Early inverters used a square wave. Light bulbs and some appliances were ok with that, but motors, chargers and other things were not happy at all about that. These are pretty much gone. They were followed by the “modified sine wave” inverter, which actually makes a modified square wave, giving the peaks needed for most equipment. I have heard all kinds of warnings against running your microwave or other things on them. I have run just about everything on them and never had any trouble, but your ceiling fans will buzz! These are rapidly being superseded by sine wave inverters as the electronics technology has advanced. Motors run cooler on these and these are your best bet in the bigger inverters.
Another term you will see is low frequency or high frequency. The power coming out in a USA model is 60Hz (pronounce Hz as Hertz) or cycles-per-second, as we old timers say, and that’s with the high OR low frequency model. The low frequency unit creates the 60Hz directly through a great big transformer. Doing so gives a little bit of an advantage for surge power when starting motors like a saw, air compressor or A/C. The high frequency models use little transformers that are very efficient at high frequencies to step up the voltage and then switches it back and forth at 60 Hz to form the output. Most of these have the modified sine output, but there are pure sine models on the market, too.
Which do you want? It is really like having a pickup truck with a conventional V8 next to one of the new ones with a turbo 4 cylinder. One lugs along slow and steady and the other buzzes along at higher rpm, but both will haul the load. If you want to carry it around, you’ll probably want the high frequency model. If you are going to bolt it down for the long haul get the low frequency unit. Your bigger models are likely to be low frequency.
Some inverters, like the ones I built, just invert. They just step up the power from your battery to 120 or 120/240 volts. That may be all you need. Consider, though, the advantage of an inverter charger. If an outage runs long, or if you are using in a solar installation, you may need to top up the battery with a generator. The inverter charger can help there. MAKE SURE that the charger will let you set the charge rate. This is very important. If you have, say, a 5548 inverter that can charge at 80 amps and only at 80 amps and you have a 2kw generator, then you have a problem because 80×48 = a whole lot more than 2000 watts. The better inverter chargers will let you set a percentage charge rate so you won’t injure your generator or the batteries. I would love to add that feature to my homebrew inverter, but that would require thinking. These days, thinking is reserved for remembering where I left my phone and keys.
An automatic transfer switch (ATS) is another grand feature to have and it is in most of the bigger inverters. What this does for you is it lets utility or generator power go through to the house and switches to inverter/battery sourcing if the primary source fails. Most of these have some selectable variations. For example, Tom runs his house on the inverter anytime the batteries have enough power and these are charged by a 10kw solar array. He does not have a big battery stack, so if the A/C runs a lot on a summer night, the inverter may switch to the power company at a preset state of charge. Alternatively, the inverter could start a generator if a hurricane took out the utility power and the batteries got low.
Some inverters also have a “sell” mode. This lets you tie a solar system into the grid to sell power to the power company and/or use the grid to store your power for later. This requires some paperwork and an agreement with the power company, especially where these new smart meters are installed. Tom’s power company won’t allow grid-tie and buy his power, so that is why he uses both, and the inverter figures out which source to use at any given time. You don’t need sell mode for a backup system and you may not need some of these other features, but they may come in handy if you get the urge to add solar, later!
Now, let’s go over some things of concern in buying an inverter. First is rated power. A lot of inverters you see on Ebay don’t even come close to spec. I saw one rated at 3000 watts, about the size of your hand and priced at $33. Folks, you will not find a 3000 watt inverter for $33 and you can’t make one that small. I blew up the photo and saw that the label said “300 watts,” which is more likely. I corrected the seller. Instead of correcting the rating, he photoshopped the label! Somewhere in the fine print there was a mention that it was 50Hz. You don’t want that if you are in the USA. Some of these cheap rigs are 240 volts, too, and I don’t mean split phase 240/120. You don’t want 240, I bet. Heaven help you if you order an inverter from Thailand or Malaysia!
Look for continuous rated power. A lot advertise at a peak rating, so that 10,000 watt inverter might be good for 2500. A unit that John sells rates it in levels. This is a good sign. You may see that it says
4800 watts forever, 5500 watts for 20 minutes and 15,000 watts for 3 seconds. These aren’t exact numbers, but this is pretty typical for a good unit. Look at the weight, too. Real watts require real pounds of iron and copper in the transformer. My big inverter (rest in pieces) weighed 185 pounds! One well known Ebay Chinese inverter uses great electronics, but they have gradually used smaller and smaller transformers. My 8kw Chinaverter has one transformer…they used to have two and they weren’t big enough, then. The result is that it can put out 1600 watts continuously and the transformer smells bad if you try to use more for a long time…but it doesn’t weigh very much! On the other hand, my ancient Trace 2524 will put out 2500 watts all day, but bring a friend if you want to move it…it has a big transformer.
Can you parallel the inverter? That means run two of them lashed together for twice the output. Tom bought a 5500 watt inverter from Sun for his entire all-electric house and he had to compromise with the loads. He could not run stove, A/C and clothes dryer at the same time, for example. He added another in parallel and can run anything he wants, now. If anything happens to one of them he can fall back to the other until repairs can be made. It is a nice feature in case you want to expand, later.
One other concern that you might not have considered is service. My 12kw unit came from an American company. I bought it used and did not do much research. Tom had used it for a number of years and it worked great. After the lightning strike, I went to order schematics and parts. It quickly became clear that the guys at the American company did not have schematics or know anything about it. They just screened their name on a decent Chinese inverter and marked it up. The price of replacement circuit boards indicated to me they were robbing parts out of a new inverter. Looking under the hood, I discovered the circuit boards were designed by the same guy who designed my wimpy Chinaverter!
I used to design circuit boards, so I can spot a designer’s trademark. So, the moral of the story is, search around on the internet to see if anybody does service or sells parts and manuals. I checked one of John’s nice rigs and the signs were good. They may have some more info on that subject at Sun, so it would not hurt to ask.
A final consideration is a seller who will back his gear. Consider anything you buy directly from China as disposable. Trust me. Again, I don’t work for Sun Electronics…I am a customer and this is a true story: something I bought from John two years ago went bad. I contacted John to see how the warranty worked with that product. He said he didn’t know, but HE would replace or refund it. He put me in touch with Louis and after sending in some photos showing the problem, Louis said he would give me a credit. No hassle. Done. Where else are you going to find that?
Next time I’ll continue onto the subject of batteries and other considerations. In the meantime, if you just can’t wait to get started, you should at least have some ideas on what you want and need. Call John or any of the sales engineers at Sun Electronics and they can get you started.
By: Neal Collier
Backup Power
Coming out of last weekend, the network news guy told us how many HUNDREDS of THOUSANDS of homes were without power in the wake of a big snowstorm, which included a lot of area where people were not accustomed to dealing with such. It looks like a little more of the same this weekend. Here on the coast, we have to deal with hurricanes knocking out power every few years, on average, but we aren’t big on ice. In the north, you hear about it several times a year with the snow and ice and I wonder, “WHY DON’T MORE PEOPLE HAVE BACKUP POWER SYSTEMS???”
Sure, some people do have generators, but that is not always the best way to go, even the automatic whole-house generators. Don’t get me wrong, those are nice and Mom loves hers, but there are better options.
I have seen these headlines and repeatedly started to write this article, only to get frustrated about which way to go with it. There are so many options and maybe that makes the decision process more complicated. On this try, I will go with just a general outline and talk about some of the equipment. Hopefully, that will help you select the right system for your house.
First, do you want something that will take over normal operation of the entire house? Or would you be happy with something that will keep some lights on and maybe power the fridge and microwave so that you can have some comfort food and a hot cup of cocoa as the cold wind howls outside?
Let’s start with generator vs. battery. I visited a popular generator maker’s website and, by golly, they can solve all of your problems, they say. They tell you that a highly-touted lithium battery system will only last 2 hours and only put out a paltry 2kw, while they can power the whole house for days. Oh, marketing guys! This is the same generator Mom has. Twice it has failed to start because the service tech left the switch set wrong. Once it failed to start because the battery had exploded (which corroded a hole in the bottom of the cabinet). Every time it starts it burns a lot of expensive (in her town) natural gas and makes a lot of racket, regardless of load. Still Mom loves it, but I get aggravated when I have to drive 32 miles in bad weather or storm debris to get it running… 92 year old ladies don’t want to be troubled with mechanical issues, but they are good at sending their sons on a guilt trip. She bought her generator after a 2 week power outage and it usually works pretty well.
The marketing guys at the big battery company have a different story. They say their wall-mounted thing will make life grand for two weeks. Maybe so, if your idea of a grand life is operating a table lamp for a couple of weeks. Their battery system costs more than the generator, more even than a couple of homes I’ve owned.
Is there a compromise? Sure. First, you need to consider what a typical outage would be. Yeah, there are exceptions to “typical”, like the time mine was out for 5 weeks and the MONTHS that the folks in the Florida panhandle are looking at, but usually the number is just a day or two. My number was 4, because I live at the far end of a rural line.
Then, consider what you want to keep running. The fridge, microwave, Mr. Coffee, and some lights are probably on your list. In the north, maybe you need to run the blower and igniter circuits on an oil furnace. YOU CAN RUN THE WHOLE HOUSE, but it will cost more. Even a portable box you keep in the garage to provide a few lights can be a great comfort! Once you have decided HOW MUCH POWER you need by figure how much the devices use and how many hours you will use them, you can start looking at the components and number of batteries you need.
Let’s talk about inverters. These are gadgets that turn the DC voltage of a battery into the AC voltage that your fridge eats. They are commonly found with an input voltage of 12, 24 or 48volts. 12 volts is usually used on lower power systems and have the advantage that you can charge the batteries with your car, that 4000 pound generator in your driveway. 48v inverters are used on high power systems because the battery current is lower and you don’t have to use huge cables. 24 volt units are a good compromise and a good choice for a system for basic comforts.
The basic inverters just do one thing, they invert. Nothing automatic is going to happen. You connect it to the battery bank, turn it on and run a cord to whatever you want powered. You could plug it into a generator plug, if you have one installed in your house. From the basics, you then have all kinds of deluxe units. For an automatic system, you have inverter/chargers with automatic transfer switch (ATS). These would typically be installed between a main breaker and a sub-panel that feeds power to whatever you consider your critical or nice-to-have loads. The big ones can run the whole house. With these, on a normal day, the utility power passes straight through to the house and a little more goes to keep the batteries happy. When a squirrel leaps to his death on a power line transformer, your neighbors’ houses go dark and you notice a slight flicker in the lights as the inverter takes over. Maybe the ceiling fan has a slight buzz, but that’s it. Sweet.
And you know? Once that is in place and paid for, it is a simple matter to bolt a few solar panels to the roof to charge the batteries and power the loads. An outage that runs beyond the “typical” one won’t run the batteries down! That’s right, the backup system is the first step to a full-on solar power system. That is where my system is now as I gradually work toward total independence from the power company.
Since this is starting to run long, I’ll stop here and let this soak in, then move on to other considerations in a day or so. If you are not technically inclined, don’t worry. This is just to introduce you to some of the basics. After you know enough to ask the right questions and decide what it is you feel you want and need, you can call Sun Electronics. John’s crew has guys who can translate your needs into a package that will fit your budget. They design tailored systems all the time and it doesn’t cost extra.
By: Neal Collier
May I?
Remember when you were a kid and you always had to ask Mom or Dad permission before doing anything so you wouldn’t get your bottom smacked? Boy, you couldn’t wait to grow up so you could do anything you wanted to do! Then you grew up and found out you still had to ask permission to do things. Bummer.
Building your own solar power system might well require you ask permission in the form of getting permits or filling out paperwork. On the other hand, it may not. I want to go through some examples, today.
Let’s start with some examples where you may do it yourself without a permit. We’ll start with some ridiculous examples like those little solar sidewalk lights. No permit, but it is solar. A more useful project would be a solar motion detector light for the corner of the garage. You actually get to use tools for that!
Let’s get a little more serious now. Do you have a boat? Sailboats and cruisers are a huge market for solar. I read the cruising forums and lots of folks are doing their own and there are some pretty serious systems. Heck, my expedition boat is 100% solar powered, even the galley. There are no permits involved, but the Coast Guard may come aboard, as they sometimes do, and they will want to see things safe. Your insurance company may require a survey, too. Use cables made for marine service, non-rusting hardware, lash down the batteries and protect things from the fingerpoking!
In fact, that general advice might be good for ANY kind of solar installation that you do. Use the right wire, make it look orderly and workmanlike, make it safe. Inspectors look for the scary-looking stuff, so don’t make it scary.
Motorhomes and RVs are another good place for DIY solar. The roofs may have vents, fans, skylights and antennae, but there is usually enough room up there to put in a good bit of solar. Mounting on offsets can allow for more solar, but may present an issue with wind lift. Besides, RVs tend to be pretty tall to start with. We have the notorious 17th Avenue Bridge in Pensacola, which has been the end to many an 18 wheeler and RV, so why tempt fate with added height? Keep it low. Know what the structure is, too. You want to get your bolts into something that will hold. A friend’s very large rig has a roof that is basically molded styrofoam covered in sheet metal! In a case like that, use lots of screws. On that rig, we considered using solar laminates (panels without the frames) bent to follow the curves and held in place with greenhouse channel. Because of all the other things up there to dodge, a mosaic of smaller panels might be the key to getting the most watts on the roof. Watch the weight, too. You don’t want to get it top heavy and go tipping over ! As long as your panels don’t come flying off, nobody will say a thing about permits for your RV power project.
Another RV project would be to have a portable setup. I know guys who go to big outdoor shows in their RVs. If they can find a shady spot, they will. Some set up panels on a stand away from their shade and can run fans and charge phones without ever having to fire up the noisy generator.
Are you a farmer or rural dweller? On the farm, most places I have seen, you are pretty much on your own when it comes to structures or electrical. I have all kinds of little solar projects for water pumping, lighting a shed, and even a major power plant that IS the shed. The smallest installation is a 10 watt panel bolted to back fender of a seldom-used tractor. I ran out of barn space, so it is rusty and faded, but, by golly, it’ll start when I need it. My neighbor Glen has some 10 watt panels I have swapped to him for welding or other favors. They are all over the place, keeping batteries topped up on equipment he doesn’t use a lot. A super low-cost farm project would be to have a small module and 12v LED light bulb for a tractor shed, using the battery in the tractor. Kill two birds with one stone, keeping the battery hot and having a light in the shed.
Now, let’s talk about permits and inspections. In most places, I can’t go out and install solar at your house because I am not a licensed contractor. You, however, as a homeowner, can probably get a permit to do your own work. We’ll talk a bit more about this in a moment. The job of the inspectors is to make sure you do a project safely and don’t kill anybody or burn your house down. That, having been said, you will sometimes find an inspector who is a bit of a tyrant and you will find inspectors who are nice guys that will work with you and help you out. There was a time when the inspectors in our county were very, very ….ummmm, well let’s just say the county had to issue them guns so that We The People wouldn’t kill them! Things have changed for the better and we have a bunch of good folks, now.
I can give two examples of the kinder, gentler inspectors. Stan has been building his “hunting camp” for years. His homemade solar and wind power system is a little dodgy, but works well and he is involved in a first class upgrade. Someone mentioned his place to the Inspections Department, which had previously failed to notice it, owing to its remote location. The inspector inspected and then declared that since there was no Certificate of Occupancy, he had no jurisdiction over the project.
Tom built a large outlaw system in his barn to power his house. He later confessed his sins so that he could go grid-tie and the inspector was nice as he could be, willing to work with Tom on bringing things up to code.
So, back to your permits, you need to go to the Inspections Office with a plan and not a vague idea. If you have a couple of ways you can go with the project, sketch them out and go and ask the inspector’s advice before finalizing things. Show respect and let the inspector know that you know who’s the boss. (Hint: it ain’t YOU!) The biggest way to cause yourself trouble is to go in with an attitude. You’ll get one back right in your face. When I built my house, I pulled all the permits and dealt with all of the inspectors. Each one may have some little quirk and may gig you on something just to let you know they are paying attention. Anything they noted, I corrected and then took to them before and after photos so they wouldn’t have to come back and crawl under the house or in the attic. That courtesy was returned with a quick sign-off on the job.
Note that in many areas, the inspectors are in the office very early for a short while and after lunch for a short while and in the field, inspecting, the rest of the time. Call ahead to discover their hours. Don’t be first in line. Let the pros get their business done and that’ll leave you more time for your consultations.
The most paperwork intensive system I have seen is Mike’s. South Carolina and Duke Power had a heckuva rebate program that would more than pay for the hardware if you shopped the right places. There was a lot of paper for the rebate program. Then, the structure over his barbecue area had to have a structural analysis to insure it wouldn’t fall over with solar panels on it. He got a licensed engineer to sign off on it. Then there were the electrical permits, which were pretty basic, and the paperwork for grid-tie, which had to be signed off by a NABCEP certified installer. THEY can be hard to come by, even with all of the solar activity we have going on these days. Things went well, though the NABCEP thing caused some delay. All that was left then was the IRS tax rebate form, which is easy and requires only receipts and no NABCEP or permits. Come to think about it, Mike may have come out ahead on the deal!
To sum it up, there are plenty of solar projects you can do without anybody’s permission. If you are going to attach it to your home, then you probably will need a permit, but as a homeowner, you can usually get one and do the work yourself. Just assure the inspectors you are competent and show them some respect. Asking their advice on how they might do a particular thing is something they usually like. John’s crew at Sun Electronics can help you with the system design, so you can go to the inspectors with a plan.
By: Neal Collier
Keep your powder dry….electronics, too
For some months, the wife has been grudgingly patient about the Trace 2524 in the living room. Why was there an inverter in the living room?
I’ve been engaged in a multi-year evolution in my power system, so lots of new stuff has been coming in and out of service. In our Southern climate we have humidity to spare and when you add temperature swings you get condensation. Stuff sweats, especially stuff containing heavy transformers. In operation, these bits of equipment put off a little heat, so they don’t sweat. The inverter spent a couple of decades in my attic, but it buzzed along happily because it was warm.
You do not want water creeping into your electrical gear. You just don’t.
The new power room in the Solar Shed is not quite a room, yet, as there is the fantail of the solar launch where the last wall should be. That will change, with the latest expansion, but until it does there is humidity. So, I have left unused things powered up to keep them warm and dry.
The 24 volt system is almost gone, now. Only one charge controller on the control panel and a couple in the launch, and the big 24 volt inverter are running because I have not run the new 120v wiring for lights and outlets in the newly expanded shed’s 48v system…and I have to keep the boat’s electronics warm. There isn’t much solar energy for the boat inside the shed, unless it comes in by wire.
The 2524 inverter is now out there, wrapped in plastic. Each decommissioned charge controller is getting wrapped and stowed in plastic storage tubs as it comes off the old control board. Some will be used in the Solar Yacht project, others will probably be used in the barn or sold. Until then, the plastic wrap should keep them fresh and dry until the control room is closed in. The heat of the control panel equipment should keep the winter humidity low and eliminate the condensation threat once the wall is in place. (Mexico has not offered to pay for my wall, either.) During the summer, there will be an a/c in there.
Batteries sweat, too. The danger there is that the moisture creates a small current path and you not only lose a little power, you get corroded terminals and attract crud. Mine are all outside the control room, now, and the hope is that an insulated battery enclosure will keep them from cooling down and sweating during the summer months.
Unless all of your equipment is in a climate controlled environment, or Arizona, add Saran wrap, plastic bags and tape to your supply list and keep your unused electronics dry!
By: Neal Collier
After playing phone tag the other day, John and I were having a conversation about all things solar and my Solar Shed phase 3 performance. He asked how well the modules were performing as these are all recycled salvage panels in the form of roof tiles.
I replied that they are doing well, having seen around 8kw with a 10kw nameplate rating. That concerned him and he seemed a little surprised when I made the point that modules never seem to make full rated power…not in the real world anyway.
You see, panels are tested and rated at an industry standard under conditions that are rarely encountered at most sites. It isn’t exactly a lie, but neither is it the real world. Never mind that mine are panels that have a permanent grime on them and were stomped and thrown off the roofs of their original installations. I have seen some panels with a second set of numbers on the label that represent a more likely scenario. These lower numbers are closer to what most folks will see.
First of all, there is the matter of the sky sometimes being reluctant to provide the industry-standard level of irradiation. In our area, we go for days at a time in winter with clouds and gloom. In the summer, with 95 degrees and 95% humitidy, we have a 10,000 foot layer of humidity that looks sorta like blue sky, but it blocks some of the sun. My Phase Two version of the solar shed had plenty of power on sunny days, but not enough battery to ride through the gloomy ones. After 4 days, I’d have to switch back to grid to save the batteries. Phase Three has enough modules to charge the larger battery pile, even on cloudy days. Getting the right balance of relatively cheap solar and expensive battery is tricky, but I think I have nailed it and have added more loads to the new 48v system.
Electrical resistance can take a small toll. Keep your cables fat and short for lowest resistance. Long skinny wires and parallel strings will give you a power loss. Each connector loses a little power. Since my system uses relatively small 34 watt modules, there are over 700 MC3 connectors up there!
Then there is the matter of the sun’s angle, relative to the panel surface. They test with the sunlight coming dead-on square with the panel. Tracking racks are available, but I don’t think they are worth the extra expense. If you have a fixed installation, then you will get that max output for an instant, twice a year. Right now, the sun is a little low to be hitting best power on my array. This summer, the sun will be high, but the days will be longer, so I am looking forward to sun-powered central air conditioning! Don’t let somebody tell you that you have to have your rooftop panels at a really ridiculous and ugly angle to improve your performance. I saw photos of a system mounted on an otherwise picturesque barn at such an angle as to make the image hideous. Mount your panels at the roof angle and just use more of them if you need to. Keep solar beautiful and fashionable. If I remember any of that sine and cosine stuff correctly, you’d have to be 60 degrees out of alignment to drop the output to half and on a cloudy day the diffusion of light by the clouds would make up for some of that loss.
I mentioned that these modules of mine have a permagrunge. Nothing cleans them! Then there is the layer of pollen that the pine trees are presently giving them between rain showers. In May, cropdusters at my place will give them a coating of red clay dust as they go roaring back and forth. That’s right, anything that blocks the sun blocks the power. The big solar farms are now playing with the use of robotic panel washers to keep the modules clean. One of those long-handled RV brush/squeegee thingamajiggers will probably do well enough for you.
There is also the temperature factor. Note on your label that your panels are rated at a certain temperature. Mounted close to the roof or even out in the open you are likely to find much higher temps on a sunny day. Output goes down as temperature goes up. The solar roof tiles I use probably benefit from being mounted on open purlins instead of a sealed plywood roof deck as code dictated in their original residential installations. Let your panels breathe!
So, if you use your panels on a cold, dry Himalayan mountaintop with sun trackers, you might come out even with the rated output of your modules. The good news is that they start making power as soon as the sky makes light, even down here in the hazy flatlands. My batteries are usually bulked up by 9:30 and it just keeps getting better until mid day. You’ll end up with 5 hours equivalent at full rated power if you live in Florida and a little less as you move northward up the map. Your mileage may vary! Since solar panels are no longer the expensive part of the system, add another string of 3 modules modules (John’s 305 watts special) for about a hundred bucks, each, for a little extra insurance and peace of mind. You won’t regret having “too much.”
(Update: Since this was written, the sun arose to a perfect angle on the Solar Shed’s roof. We’ve even had some unusually clear days. I isolated one bank rated at 2500 watts and actually saw 2475 watts on the meter at noon. Close enough! This will drop off as the sun continues toward a higher arc, but the days are getting longer so there will be plenty of power.
By: Neal Collier
Increased output from fractured cells
I looked for that article we were talking about, regarding fracturing cells for greater output. I found lots of articles on how fracturing can reduce output, but not the one for which I am looking. I did find a patent for manufacturing cracked cells to increase output.
Patent for fracturing cells. Link
Here are my observations on the subject. I test my panels with an ammeter instead of a voltmeter. A tiny section of a broken cell will give the same voltage as a full cell. Testing with an ammeter, I feel, gives a better indication of the power capacity AND gives a bit of a stress test. That assumes finding a sunny day here in the alleged Sunshine State.
Virtually all of my 34 watt, 6 volt panels have one or more cracked cells, at least in the later pallets. This worried me, at first, but I have come to embrace them and have enjoyed studying them. These tiles have much thicker glass than you find in standard modules. That allows a great diversity in crack modes without breaking the glass. The cracks that concern me the least are longitudinal ones across the fine silver traces between two main bus bars. There is no degradation at if the tiny silver wires are intact. If they are broken, the current still flows to the nearest bus bar. Outside of the main area, A crack with broken wires would eliminate a small amount of current from reaching a bus bar.
The ones that really concern me are the ones made by someone really serious about destroying a panel. These cracks fan out over the entire cell, looking like lightning bolts or, perhaps, a fern. The cell ends up in lots of pieces with the potential that several of those fine lines will fail, drastically reducing output. Given the choice, I choose the panels with the simpler cracks.
That being said, label-rated short circuit current should be around 7.5 amps, if I remember correctly. In practice, I have observed as much as 9 amps on these modules with multiple cracked cells. With such variation, I feel it is probably important to sort the panels for similar outputs, even as simply as Hi, Medium and Low, to maximize the overall production of power.
Have any failed? Hard to say, because I run in strings of 21 and they have bypass diodes. I do know that I had 2 with the edge delamination problem and their diodes were bad. 3 foot jumper cables allowed me to bypass those and continue operation with the rest of the string.
Some of the tiles were received with the glass smashed. That usually resulted from screws being left in the tile above. There were also some piles that were simply stacked too high and cases of probable malice. Not surprisingly, cells were damaged, too, when the glass was smashed. Usually, these modules work! I have one on the solar shed that has broken glass from a tree strike after installation. I tried to seal it with some of that miracle AS-SEEN-ON-TV clear sealant. It did not stay clear more than a few days and ultimately crumbled off. It turns out, though that the sheet of sticky plastic between the glass and cells maintained a seal and the tile with the broken glass still has good output, though in Phase 3, it is not presently connected.
This is not to say that all cell fractures are benign or beneficial. You’ll recall the panel I blasted with the shotgun. That did not really affect that module, but then it was already somewhat handicapped by having been bent and bowed by Tom’s front end loader getting “just a little too close.” (Right. Basic laws of physics indicate that two things can’t occupy the same space at the same time, for every action there is a reaction, and while matter can neither be created or destroyed it can be smashed to bits.)
While I am still a bit shaky on the physics of less-than-perfect solar cells, I am fully aware that my lights are on because around 350 previously discarded panels are keeping my batteries charged! If they work, use them, but please don’t take a hammer to them! Or a tractor.
By: Neal Collier
Basics
I started taking old radios apart as a very young kid, began my career in electronics at 16, was a licensed broadcast engineer at 19. That led to computers and all kinds of electronic gimcrack design. Having been making sparks for so many years it is easy to forget that some of the basic stuff might seem scary or mystical to folks just getting started. Today, let’s look at a couple of very basic and very important terms: series and parallel.
You will run into the use of series and parallel connections in solar power work, most importantly, perhaps, in the connections of the batteries and the PV modules. We’ll start with batteries.
Series: Have you ever seen a picture or video of a bunch of elephants walking in a line, trunks wrapped around the tail of the beasts in front of them? If you can conjure up that image, then you can get the idea of a series connection. Let’s say the trucking company just delivered 8 Trojan T105 batteries that Roberto sold you when you called Sun Electronics. What do you do with them?
They are 6 volt batteries, meaning there are 3 cells of 2 volts each connected in series. Now, 6 volts is not terribly useful in most solar power arrangements, which are usually 12, 24, or 48 volt systems on the DC side. So if you take 2 of the 6volt batteries you can make 12 volts. With 4 you can have 24 volts. 8 X 6 makes 48 volts. Easy, right? BUT, how do you connect them?
In series connections, you connect a cable from the first battery’s “+” positive terminal to the next battery’s “-” negative terminal. Just like the elephants, but not as heavy. Now, if you take a meter and put the black lead on the first battery’s negative terminal and the second battery’s positive terminal, you’ll find that the meter should read something over 12 volts. Ta Dahhh! You’ve just made a series connection. Add two more batteries in the same fashion and you have 24 volts. Add the rest of the batteries, trunk to tail, just like the first 4 and you end up with over 48 volts. If you put one in the string of batteries backwards, the 6 volts of that battery will be subtracted and the voltage will be below 48v. Pay attention to what you are doing!
Note: These cables need to be pretty fat because you may be dealing with hundreds of amps to feed your inverter. We’ll talk of that another time, but if you ordered a kit from Sunelec, you’ll have properly sized cables.
Parallel: Ok, you have 8 batteries and you have a 24 volt system. You placed 4 of your T105s in series to make 24 volts, but you still have 4 batteries left. What to do with them? Simple. Just make another 24 volt series of batteries right next to the first set. Make sure both lines have the “+” at the same end and connect those positive terminals together. Same thing with the 2 negative terminals. Now you have 8 batteries and 24 volts. This is called a series-parallel connection because you are connecting series strings of batteries in parallel to increase POWER (not voltage).
If you only have 24 volts and you can get that with 4 batteries, why do we use 8? We double the storage capacity this way. Let’s say the T105 is rated at a capacity of 220 amp-hours (AH). With one string we can multiply 220 AH X 24 Volts to discover a capacity of 5280 watt-hours. Let’s just round that off to 5000 or 5KWH (KiloWattHours). When we add the second set of 4 batteries, we double our storage to 10KWH. 10’s gotta be better than 5, right? You betcha.
Wait a minute, you are saying, I have a 12 volt system! You know you get 12 volts from two batteries, so do you connect 4 sets of two batteries? Exactly! With this connection, you now have 880 AH of storage and still have the 10KWH power capacity of the 24 volt system, just at a different voltage. If that’s confusing, don’t worry about it…it’s a good thing.
Here are some tips.
- Take a can of white paint and mark the POSITIVE corner of your new batteries. Trojans are dark red and the Sun batteries (and most others) are black, so the white paint will stand out better to avoid confusion.
- Have a multimeter. Even a cheap (or free with a coupon) one from your favorite Chinese tool store is all you need. Check each connection as you go to avoid sparks later.
- Wear safety glasses…some batteries can make sparks and hydrogen and under certain conditions that can be a bad thing.
- Cables that are too big are better than cables that are too small.
- Put shrink wrap or tape around the transition of where your cable goes into the terminal.
- Don’t make your cables any longer than they need to be. Big wire costs big money and long wire has more resistance.
- Put a coating of grease or battery spray on the connections to avoid corrosion.
- Cheap bolt cutter make dandy wire cutters when working with large battery cables.
If connecting that last cable to an inverter or other device containing a large capacitor, you WILL get a spark, so tap the cable to a flat spot on the terminal and not the screw stud (if applicable) to avoid making a weld burn that will make it impossible to tighten the battery nut. A better plan is to make the last connection at the inverter or fuse/breaker. Good Luck
By: Neal Collier
More Parallel and Series Stuff
The other day we talked about series and parallel connections of batteries. You know, getting 24 volts using four 6 volt batteries in SERIES and getting lots of amps at 24 volts by using 2 of those 24 volt strings (8 batteries total) in parallel. What about connecting your solar modules? Yes, it applies there, too. These roof tiles John is giving away, put out about 4 volts under load, so you use 3 of them in series to charge a 12v battery. I use 6 in series to run my 24 volt backup water pump. If you have a battery system and use an MPPT charge controller you might run 3 modules in series to get a good efficiency and stay under the 150 volt limit of the controller. If you are connecting a grid tie system with a string inverter, like a Sunny Boy, you may connect lots of full size panels for a voltage around 600 volts!Six 4v panels in series to run a 24v water pump located near my spring.
Connecting your solar panels in series is super easy and it saves money on wire, because several panels are connected using a single pair (positive and negative) of wires to the controller. Your modules probably have MC3, MC4 or Tyco connectors on them. Pick one connector on the first module and it will plug into the right one on the next module. The other one gets plugged to the next module. (If you use John’s free solar roof tiles, you might want to buy a sack of MC3 connectors because there will likely be some missing.) You can’t just do this forever because those panels are usually good for around 40 volts on the big”24 volt” panels and 18 or 20 on the “12 volt” panels. You could get some scary or damaging voltage added up in a hurry.Let’s say we have a 60 amp charge controller on a 24 volt battery. I don’t have particular specs handy but, generally, you’d say 60 amps X 24 volts = 1440 watts. Some controllers are real fussy about input wattage and even fudge a little bit on the specs. Some are rated higher and seem to just ignore a little extra power. Just remember 1440 for now.If you take three 300 watt panels and put them in series, you’ll have a max voltage of 120v, which is fine for this controller. Of course, 3 X 300 watts = 900 watts, so that being less than 1440 watts, you are safe to go. Sometimes, though, you have lots of cheap solar panels and want to get the most out of your BOS (Balance of System), so how many of these 300 watt panels can we use on the single 60 amp controller on this 24 volt system? Take your 1440 and divide by 300 and you get 4.8. You’ll have to round that down to a whole number, so that gives you 4 panels you can use.If you hook all of these panels in series, that’ll give you 160 volts on the input, so that is a no-no, as it exceeds the 150volt rating. TWO of those panels in series make 80 volts and that is ok. So if we take two in series and two MORE in series and connect the two sets in parallel, we can run 1200 watts (4 X 300) at 80 volts (2×40) into our charge controller and all will be good. If you have more panels you’ll have to have more charge controllers, or bigger ones, and calculate the optimal connection.TIME OUT! If you are getting scared or confused about 80 or 150 volts from your panels charging a 12, 24 or 48 volt battery…relax! MPPT controllers are magic! They detect the battery voltage and squeeze that higher voltage into your battery and get 20-30% more power out of the panels in the process. Don’t worry about how. Like I said, it’s magic, like using a 120 volt outlet to charge your 3.7 volt cell phone battery. Trust me.Now, there are exceptions to this general plan and that comes in the actual specifications of the controller you are using. A FlexMax 60 is rated at 1500 watts instead of 1440. This is from a real-world example at Stan-the-Hermit’s cabin. He has ten 300 watt PV modules and two 60 amp charge controllers. What he planned to do was put 5 panels in series on each charge controller. NO! Stan, don’t do it!!! The watts would be fine, but he’d have 200 volts going in, which would cause the smoke to come out. You never want to make the smoke come out of electronic stuff. (According to the Leo Ginn theory, electricity operates by the circulation of smoke molecules, so don’t let the smoke out.)The old 12 volt system was all wrong…and worked great.
What should Stan do, then? I don’t normally recommend sacrificing the low light capabilities of MPPT charge controllers by operating all of the modules in parallel, but that is what he will do on the new system because he’d rather spend the money on his girlfriends than charge controllers (which are less expensive). 5 panels in parallel on each charge controller should work fine. There are MC4 adapters that allow parallel connection of modules, saving wire and making parallel connection easy, but watch out for the current capacity of the wire you are using. A single 10 AWG pair will safely carry 30 amps, but will lose a little power in the wire. I buy a 1000′ roll of cable (wire gets cheap on the big rolls) and every string gets its own wire. This allows me to isolate a string with a bad panel, if one should fail in my system of all recycled salvage modules.Stan poses with his stack of 300 watt panels and my load of solar roof tiles in Miami.
Is there any other way of doing this series/parallel stuff to save money? Yes! A SINGLE 60 amp charge controller will handle all of his panels if he goes to a 48 volts system, because it still handles 60 amps. At twice the voltage you have twice the watts. On the old 12 volt system, he’d have to have twice as many charge controllers to run with all of those new modules! He’s going to stick with 24 volts, though, because he already bought the inverter.Stan’s solar shed. 2 old men, one rickety ladder and 600 lbs. of panels.
Here is something important to note and it has to do with MIXING panels sizes. Normally, you’d buy all the same modules and assemble your system, but there are those of us who are scroungers and have all kinds of stray inventory. When connecting in parallel, you need to connect modules of the same voltage output. Don’t mix 12 volt and 24 volt panels and don’t mix 60 and 72 cell panels. In series, if you have panels of different ratings, there is a chance of letting the smoke out, but it is a sure bet that you won’t get the full added output from the modules. You CAN use a hodgepodge of panels, but group similar panels on their own charge controllers. For example, if you have four 270 watt 60 cell panels on one charge controller and four 330 watt 72 cell panels on another charge controller, then everybody will get along fine and the smoke will stay where it belongs.By: Neal Collier
Enough is enough? Nah!
Can you get too much solar power? Spend too much time on Pensacola Beach and you’ll think so, and have a red face to remind you. But, no, I am talking about photovoltaic power. In the case of grid tie, it has gotten to the point in some places that they are having to add battery storage systems to balance things out. The lack of battery saw the advent of the “duck curve” in utility power production. Look it up.
On your OWN independent power system, can you have too much? In phase two of the Solar Shed project, I had gobs of power on a sunny day, but not having enough battery and reaping only 10% of rated power on a cloudy day (we have them a week at a time in winter) made me wish for more power. Phase 3 gave me LOTS more power as the shed went from 32′ to 80′ of solar roof. Now, I am finding some interesting conditions to which I must adapt.
In addition to more power, now around 10kw rated, there is more battery storage and more on the way as I get to the detail work. The flooded lead-acid batteries are fine, now 3 days into a cloudy spell, though next year’s Phase 4 should keep them really topped.
What about sunny days? If the day starts out clear, I see what I saw on my solar boat expedition, the batteries start charging at the crack of dawn and ease into a full charge without any stress on the system. (When not on the boat I make a point of sleeping too late to see what my system is doing at dawn.) What happens, though, if the batteries are low and the day starts out cloudy and suddenly the clouds part to reveal full, noontime sun? OH CRAP! Think about that for a moment. 10kw at 48 volts amounts to 200 amps of charge current into my 635 amp battery. That comes to a C3 charge. Batteries love a C20 charge, or a rate of about 1/20th of the A/H rating of the battery. They are ok with C10, but they will use a little more water. But C3??? Bubble bubble, toil and trouble, to misquoteThe Bard. If you have sealed AGM batteries, they will soon die a horrible death at that rate.
My system has big knife switches I can pull to disable strings of panels in sunny weather, but that hardly seems a good way of doing things. You really want this to all be automatic. So far, the only issues I have had is when the batteries are topped and then the sun abruptly comes out. My inverter blinks the power off and back on! Why? Well, the charge controllers, which are set fairly close to the overvoltage trip on the SunKing 5548 inverter, take an instant to react to the increase solar power and the inverter trips. So, what to do?
The inverter is very adjustable, but everything is working the way it is set up and it really isn’t it’s fault, so I will leave it alone. BTW, you can’t buy a SunKing 5548…I built it out of the ruins of my lightning-killed previous inverter and some driver hardware I found. (Note that the Sun Electronics kits include the lightning protector that I NOW use.) The next place to look would be the charge controllers. I have 4 and three different models. I don’t recommend having a bunch of mismatched hardware, but I ended up with leftovers from evaluating hardware for my Solar Yacht project. As I noted in a previous blog, each has a different personality and each is adjustable. The two least active, get satisfied early in the day and shut down. They are not a problem. The twins are very active and are where the trouble originates. I dug through my literature stack and found the manual and went through the setups, dropping the maximum on one and dropping it some more on the other. I’ll know if this did the trick sometime in May, when the sun comes out again. I will just tweak them until the maximum charge current is at a rational level under full sun.
Are there other remedies? Glad you asked! Yes, there is a gadget called a Diversion Load Controller. I think these were first used with wind generators because you can’t just disconnect a windgen in a stiff breeze or it might fly apart. It used to be that the cost of solar guaranteed that no one would have too much solar power, but that has changed. You can use the DLC to dump power into a giant resistor, but that is wasteful. A better plan is to find a 12, 24 or 48 volt water heater element, as appropriate, and dump the excess power into your water heater. It just screws in. Everybody likes a free hot shower, right? That won’t do in my situation because, first of all, the Solar Shed is 200′ from my house and, second, my water heater is wood-fired.
The way I will use the DLC, if needed, is to pull in a relay that disconnects some of the PV strings.So, can you have too much solar power? I’ll let you know next year when Phase 4 brings another 5KW online, because, so far, I am reveling in what I have and adding more loads.
By: Neal Collier
I want to talk about the Solar Lifestyle and what that means. Elsewhere, I have given links to the Home Power Magazine Archive. That is a treasure trove of information and each issue is a time capsule of where the state of things was at that time.
Early on, solar panels were small and expensive. I have paid up to $11/watt for solar panels and I was not exactly a pioneer. Early adopters would have a single panel of maybe 30 watts and whatever batteries they could scrounge. Battery scrounging was easier back in the day, with a choice of Edison Batteries from the railroad or a forklift, NiCads from military surplus or L16s from department store floor scrubbers. They quickly found that an old car battery was not a good choice.
Systems were 12 volts, borrowing car tail light bulbs for lights and car radios for entertainment. If you wanted to get fancy you could use light fixtures from RV or marine sources. Primitive? Yes, but if you’ve ever lived with light from kerosene lamps, then you’d think it was great.
Inverters? What inverters? The first ones were square wave and didn’t get along well with some appliances, but even those were rare. The solar power was mostly used for light. You’d cook with propane and your fridge, if you had one, used propane too.
As systems grew, low voltage appliances were added. You could get a 12v coffee pot or popcorn popper at a truck stop. Specialty houses developed super efficient refrigerators with DC motors. John still sells the fridges because there are still a lot of low power systems out in the boondocks. People found that keeping up with the loads was a struggle for the solar panel. Maybe they’d eventually add more as the budget permitted, but most also maintained a backup generator, often a homemade DC rig using a gas engine and a car alternator. This was necessary, not only to keep up with the load, but because batteries need equalizing and that takes a lot of power.
Inverters evolved, rising in power and dropping in price. John’s recent email blast had an inverter at 1/3 the cost of a similar one I bought 30 years ago, wholesale, and the money was a lot stronger back then. They keep getting better and adding features. I just saw a brochure for the Midnite Solar MNB17-5 and I WANT ONE!
So, what is the state of the solar lifestyle, today? It is a wide range. Some folks are in pretty much the same place early USA users were 30 years ago. I know a guy who brings solar power to remote South American villages and John gives a lot of stuff to folks in Haiti, where just having a light and a way to charge a phone, a modern necessity, are luxuries.
I know a fellow who is a little more advanced than that, having to fire up his generator to run the water pump to fill his tanks. His stove and fridge are gas. Beyond that, he has CF lights all over the house and a big screen TV. If he has a big party and everybody falls asleep with everything turned on, he may have to run the generator to get the batteries back to speed. His batteries, by the way, were scrounged from a phone company for $5 each and have been in service with him for years.
Another fellow has a grid tie system. In his large modern, all-electric home, he is oblivious to any lifestyle changes. If he needs more than he makes, the grid supplies it, but as a rule, the solar power covers his needs. If the grid goes down, he’ll be in the dark like his neighbors.
In my area, we can’t have grid tie. One fellow uses a hybrid system that runs on solar, when he has it, and switches to grid when the batteries get low at night. That is an automatic feature of many modern inverters. A bigger battery stack would probably allow him to go full time off-grid. A lifestyle change would, too, but his house uses a lot of power for HVAC and there are always computers and home entertainment devices running. There have been a few lifestyle changes to maximize the use of the solar power. Big power users like the clothes dryer and the oven, for baking, are used during the day. When he had a single 5kw inverter, care had to be taken to not run the A/C, oven and clothes dryer all at the same time. Under pressure from his wife, he called Sun Electronics and bought a second 5kw inverter (I think he uses the Radian series) to run in parallel and now there are no restrictions on using stuff at the same time. If a hurricane takes out the grid and spares his array, he can conserve power and get along fine on solar alone.
On my system, at Phase 3, I am gradually getting to where I want to be, adding loads. I KNOW my wife is not going to deal with lifestyle changes, so I am working toward 100% off grid with operation being completely normal, except for the size of the power bill. In Phase 2, I had a crappy inverter with nowhere near the capacity it claimed, so I had to be very careful. I bought a 12kw inverter, a real one, that was going to solve all of my problems, but then lightning took it out. I am now running a 5500 watt inverter I built. I am still learning what it can do, wondering if it will handle the A/C load when I bring it on.
Battery life was a problem with Phase 2 in cloudy weather, but I have added batteries and incorporated other sources from my 2 electric farm trucks and my electric boat. That, along with an extra 5kw of solar and the batteries have been fine, even when we go for days without sunshine.
My goal is to have no restrictions on my use of solar power. Current loads are all the lights, computer, satellite, TV/DVD, 2 refrigerators, a freezer chest, 2 coffee pots, microwave and dishwasher. If the grid goes down, the clothes dryer and the stove won’t work, but I can get by without them. If I have any problems with the A/C then I’ll just have to build or buy a bigger inverter, won’t I? Another option would be a second inverter just for HVAC. Out at the Solar Shed, I run all manner of power tools, including a 2hp air compressor and a welder. It doesn’t sound like I have too many limitations, does it?
So, you see, today the solar lifestyle is only limited by your budget and covers pretty much the entire evolution of home solar power. Solar is now the cheapest form of power generation. It is only the up-front cost of going solar that holds us back, and John is doing his best to make that cost ever-lower. Looking at some of his kits, I am wondering if maybe you could borrow money to buy the kit and pay it back with payments similar to what you’d make on your power bill. Better yet, save up and then give the power company the boot.
(Update: I did get the upstairs central a/c connected and it did not work. There was too much surge load at startup with this 30 year old machine. I installed a soft starter on the a/c compressor and now the
18,000 BTU compressor works without so much of a blink, even with other heavy loads running. Trademarked names for these gadgets include Smart Start and Sure Start. They are not cheap, but cheaper than a bigger inverter!)
By: Neal Collier
Cut Out The Middleman
Utility power began with a fight between AC and DC systems. Thomas Edison promoted DC distribution. His ex-employee Nikola Tesla, the real Tesla, came up with the AC system for George Westinghouse. Both sides advertised how dangerous the other way was! What a way to promote a new industry!
Power stations were not the huge plants of today. They’d be tucked into a building on a corner and lines would run out a few blocks in each direction. There was no grid. The first microgrids?
DC lost out because you just couldn’t send it very far without a voltage drop. AC could counter the drop with transformers to boost the voltage. With this extended range, The power plants could be bigger and send the wires out further. Plants were also interconnected and the grid was born, making for more reliable power…except for country folks.
Country folks had to make their own electricity, usually using a gas generator like the Delco Light Plant, a Jacobs or Wincharger windmill, using battery for storage, or even a small hydro plant. Henry Ford had a hydro plant on his estate. These systems were the forerunners of the independent power plants you and I are building with the clean and quiet solar systems. They fell by the wayside when the Rural Electric Administration began subsidizing power cooperatives for the rural areas.
The power companies started dabbling with solar when they saw how many of their customers were adding solar. Prices dropped and then solar became cheaper to build and WAY cheaper to produce power, even when they had to buy batteries, which are now all the rage. The power companies began building solar farms. Then they started a campaign to discourage or even prevent US from building solar capability for ourselves. Recent power industry sources now openly admit this.
Here is something a little funny, though. They seem to be on the verge of dismantling the grid system, at least on a small scale. Recently, an Australian power company was faced with upgrading a line to the boonies. Instead, they cut that project and installed small solar plants at the far end of the line. The customers saw no difference and the power company both saved money and still retained control of the power. You have to wonder why the ranchers didn’t just make their own solar plants and be done with power bills. Closer to home, a long line in the Appalachians avoided an upgrade by adding battery. This morning, I see a report that ConEd, Mr. Edison’s company, is working on alternatives to upgrading lines that are struggling under peak conditions. It won’t surprise me if they eventually add solar in the mix. Puerto Rico’s thoroughly screwed up system seems to be moving to solar and microgrids.
So, the question is, if the power company admits that solar is the way to go and solar is cheaper than conventional generation, why isn’t everybody doing it? Probably because of the upfront costs or maybe the word just hasn’t gotten out that the upfront costs aren’t that bad. John’s sales guys have payback examples for their package systems. Take a look and you may decide it is time to cut out the middleman, or at least have some backup and independence in the event of a utility power failure. My lights don’t go out. Ever. Not for 25 years. NICE.
By: Neal Collier
New System, Problems, Solar Daiquiris
Stan-the-Hermit called Friday, needing some bits and pieces to finally get his 24v solar power system running. He’s had his panels for well over a year, having accompanied me on my final run to John’s old Miami Gardens warehouse. They’ve been mounted for months. He left my place happy with an armload of switches, breakers, fuses and solar wire. If I had more friends like Stan I could open a solar hardware store.
I expected to receive a triumphant phone call within 24 hours, but that didn’t happen. He was in a panic when he called Saturday. He’d hooked it all up right, he claimed, but the voltage on the batteries had gone from 17v down to under 13 overnight. What could be wrong? The answer is right there, but let me give you some background.
A while back Stan told me he’d found a Great Deal on some used batteries that came out of a motor coach. “Great Deal” and “used batteries” can, but do not always coincide. Given the voltages he quoted at the time it was clear that they needed a good charging and equalizing and that one might have a dead cell. He did not charge them, resulting in 4 six volt batteries adding up to 17 volts when he connected them in series. I suspected I knew what the problem was and asked if he had read the manual.
“I hooked it up right,” was the answer, but not to what I had asked, so I asked twice more. No, he had not. I braved 4 miles of bone-crushing gullies, terraces and switchbacks to get to his cabin to take a look. He had hooked it up right, as he’d claimed, but it was settled in on 12.8v, which is fine for a 12v system and a real problem for 24v. He could not find the manual, of course. I suspected the charge controller had autodetected the system voltage as a well-charged 12v system and proceeded to run the battery down to 12v overnight.
We hot wired two panels directly to the batteries to get them charging. I left him with instructions to let them get up to a bit over 30v so they could equalize and desulphate and to keep an eye on the water levels. Batteries that dead should have taken a few days, but he was impatient. By Sunday morning the voltage level had come up to 27 volts and he was ready to hook up the charge controller and inverter. That is not what I had prescribed, but it would not hurt anything and might save some damage that could occur if he went away, leaving the batteries unregulated.
I stopped by about 6:00 Sunday afternoon and Stan was a happy camper. I poked at the charge controller and saw that the battery was still taking
50 watts, even as the tall trees up the valley slope were shading his panels. He’d had some of his inner circle over and they’d inaugurated the new 24 volt power system by making daiquiris! It was clear they’d been successful in that endeavor.
He still has 8 more panels and another charge controller to connect before it is done. When he moves his Flexmax 60 over from the 12v system it will be just the ticket for getting those batteries equalized because it can be manually set up for a thorough job, unlike a lot of other controllers that give a mild boost on a daily basis.
By the way, I found the manual online and his charge controller autodetects a 24v battery in a range of 18-30v, so it really did think it was dealing with a 12v battery. Whether you buy your batteries new or used, charge them up before storing and again before putting them into service. Just sitting around discharged is bad for them and confusing to a charge controller. RTFM (read the fine manual).
As for what you use to test your new power system, a blender is as good a start as any.
By: Neal Collier
Time to Hang it Up!
I like wristwatches, especially ones with classic art deco styling. I quit wearing them when I had my hands in commercial radio transmitters a lot. Other people got away from wristwatches for a while, having their phone has an accurate timekeeper, but watches are making a comeback. They are becoming quite the investment, too.
If you have a Patek Phillipe Grand Complications Celestial model, you probably have your people work on your solar system. I leave the Girard Perregaux Gyromatic in the watch box when I am just knocking about, preferring one of my big Timex Weekender variants because I can see the contrasty face with my iffy eyes. Whatever is on your wrist, maybe it shouldn’t be when you are working on your solar power, or any electrical equipment.
One of my pieces of safety equipment is a long screw on a low rafter, off to the side of my control panel. You could use a nail or, if you have a finished room, maybe something civilized like a Shaker peg. That’s to hang the watch on, along with any rings or other metallic accessories you might have.
Whether it is a Timex or a Tourbillon, hang it up when working around power.
Getting a watch into solar string voltages will make for a real nice conductor, allowing you a fairly quick, if agonizing death. A 12v battery might well weld you into the circuit and give you an awful burn. The nylon or leather straps on two of my Weekenders make them smaller targets, but targets just the same. Getting into a 24v circuit with a Twist-o-Flex you might be able to save the hand if you are fast enough. The heavy stainless bracelet on my Wittnauer or my Lord Elgin in contact with a 48v circuit might well just burn the hand off as the band vaporized.
Sorry to sound so gory, but safety is no accident. In this case, prevention costs a couple of cents for a nail and a few seconds of your time. Hang up that Portugieser and get to work!
By: Neal Collier
Why not?
I figure anybody who has built a solar power system has good reason to take pride in their work. I know I am proud of mine, but now I am a little dismayed. My system is just a solar-roofed shed. It is practical and it works, which is fine, but now I have seen that others with a little more room and a bigger budget are also having fun with their systems. I am jealous.For example, there is a Duke installation at Disney Orlando, like you couldn’t figure that out for yourself.
And what is the national symbol of China? The Panda. There are over 100 panda-themed solar power stations in the works. The photo below is a design rendering, but this station is now on line. They use different panel coatings to get the shading.
Fiji is getting in on the panda craze, too, though this one looks crudely photoshopped.
And here’s a nice one in the “heart” of New Caledonia.
Y’all make some solar power, but let’s have some fun with it, too!By: Neal Collier
Waiting my turn in Nawlins
Is that a smile or did I just put my elbow down on a hot PV module? I’m catching some rays through the sliding module hatch of my solar expedition launch, Sun King. This is at New Orleans, home of the weirdest lock and drawbridge combination I have ever seen. 1620 watts of “B” panels on the boat.
Are you afraid of “B” panels? I’m not. I put six of them on my solar-powered expedition launch Sun King and travelled up to 1000 miles from home. My longest trip was 1920 miles in 44 days. Lots of rivers and the Gulf of Mexico. These days I don’t wander so far off and only have 3 modules in the middle and rounded edges on ends. 9 big 335 watt panels are going on my solar yacht project and I plan on taking that on a 6000 mile trip around The Great Loop. “B” panels are reliable and cheap, so you can afford more solar stuff, like batteries and charge controllers, all of which Sun Electronics has, of course.
Just planning to keep the batteries charged on your sailboat or cruiser? Save money with so-called 24 volt panels instead of 12 volt panels. Use an MPPT charge controller and the 24 volt panel charges your 12 volt battery bank at top efficiency. By: Neal Collier
Solar everything, even the honey dipper!
If you spend much time around boats you know that you can’t just flush overboard. The holding tank has to be pumped out on occasion. Now there is a solar-powered roving pump station.
In my opinion, they got this wrong. There is way too much motor on this thing, probably because it was set up by the motor maker. Or maybe they can actually get that rig up on a plane, for speedy service. Torqeedos have a fair reputation if you can tolerate the noise they make. Where it is underpowered is up top.
They are going to have to plug this thing in at night if they use it much or if it has to travel very far. It is a FREE service for boaters and won’t use any gas, so I shouldn’t be too critical.
By: Neal Collier
Photo credit to http://www.solardaily.com
Inquiring Minds Want to Know!
Over the weekend we really went to extremes to show just how tough solar panels can be. Today we’ll tell you the results.
We started with a Suntech STP280 that had been hit by a tractor. The frame was bent, wires were ripped loose, glass was shattered and many of the internal cells were broken. Short circuit current of a shiny new panel should be around 8 amps. Open circuit voltage should be 44V. In the “as found” condition, we had 4.5 amps and 43 volts. Connected to a load we could get about 68 watts. Not bad for a module someone had thrown away.
Especially for a panel that looked like this.
And to recap what happened next:
After the shooting, I measured output under varying conditions. The hole sure was a handy place to put a voltmeter!
And the open circuit voltage was….39V.
Next I added a 24V driving light as a load. The lamp pulled .961 amps at 24V or 23 watts. That’s all the lamp needed. Was there more?
Next, I added a 12V battery, to be charged, and an ammeter.
Now we have 2.508 Amps at 13.8 Volts for 34 watts.
How about 2 batteries in series and the light? 26.2 Volts X .880 Amps = 23 watts
Here’s a look behind the scenes…no trickery, just honest destruction.
Conclusions? Obviously, PV modules work better if you don’t smash them with a tractor, shoot them with a pistol and shoot them again with a shotgun. The worst damage appears to have been done by the tractor. That hit took it down from 280 watts (rated) to 68 watts. The first two shots, from a .45 and a 12ga. slug, had no effect on the output. It was the huge hole from the shotgun when I backed up that cut the output in half. The point is that the panel continues to output usable power and it did a good job of topping up those batteries.Oh, and remember “Don’t Try This At Home.”By: Neal Collier
Here’s a handy idea for after a storm
You know those little solar sidewalk lights? You can put them outside during the day and bring them in at night. I wouldn’t read by one, but you can find your way around the house with it and it is safer than a candle. Most of these have a AA or AAA battery in them, either NiMH or NiCd. You can put regular alkaline AA or AAA batteries in them if you want them to run all night.
Just keep them inside and they will last for days, if you don’t want to worry about someone stealing them or have them submerge when it floods. Whenever I remove a battery that won’t run the blood pressure machine or other small gadget, I put it in a box if it has any life left in it. They will still last a long time in a super low drain application like running that one tiny LED in a garden light!
This works in a condo, too!
By: Neal Collier
Battery Connections Illustrated
Elsewhere in the blog page is a post about battery safety. I have a couple of battery photos to illustrate what I was talking about the other day, easily making battery polarity easier to see. The old 24v battery strings have decent cables, grease to seal out corrosion, but they are a bit dirty and it is hard to see the polarity, should I need to reconnect anything. You can see where I marked the 2 gauge cables + and –.
The batteries do get cleaned up every time I add water and it is about that time.
Here’s the new set for the 48v system, with painted corners to mark polarity, color coded heat shrink on the 2/0 cable terminals, dates on the batteries, grease on the seal and the terminals. This is much easier to identify things. In lieu of shrink tubing, you can get electrical tape in different colors, too. Batteries are the SUN230 golf car style from Sun Electronics.
When the new wall goes in for the power room, I will build a proper battery box to keep out the dust and dirt. I use plywood and 1×2 strips painted with latex paint. My last battery box was nearly 30 years old with no acid damage because latex paint is acid resistant! The original battery rack was steel and was in pretty bad shape after those years. I have gone to wooden racks and they seem to work well. I’ve never had any worry about fire, but lining the box with latex painted drywall will ensure that nothing burns.
The floor gets painted with latex, too, and I put in a layer of vinyl flooring. I leave a dusting of baking soda on the floor, just in case, and keep a box or two of baking soda around to neutralize any acid spill. Of course, John sells sealed batteries if you want to avoid that issue.
By Neal Collier
In defense of crappy free solar roof tiles
John’s right, the quest for attractive and practical rooftop solar with these tiles was a flop. Some of it was design flaw and some of it was improper installation. I hope Mr. Elon Musk, who is marketing solar roofs, has investigated this matter lest his quest should fail as well.
Stan-the-Hermit poses with 10 conventional panels for his cabin power upgrade and 300 roof tiles at the old Miami Gardens store.
I know about the tile problems because I have hundreds of these tiles. No solar panel works well when it is hot. Screwing them to a plywood deck leaves no space for cooling air circulation, inviting poor performance, at best. The heat also affected the wiring, some of which was made with insulation that lacked the proper plasticizers, so it just crumbled away. The heat and a poor choice of sealant caused the glass to separate from the cells, on some, allowing moisture to corrode busbar connections. The way roof shingles are installed, you can’t just pull out a bad one and replace it. You have to remove everything above it to get to its 4 screws. If one of a string of 200 goes bad, then you have no power. And, let’s not overlook a worker’s ability to screw something up. Many of the tiles I got never had all of the screws installed and some had pinched wiring. Combine high heat, 600 volt string potential and bad or crimped insulation and you are just asking for trouble. While none of these tiles ever burned down a house, there were a few smokers.
Then, consider their deinstallation. Very few I have received did not have the imprint of a size 11 boot in the grime on the glass. They were walked on, stomped on, thrown off the roof and piled high, sometimes with screws still in them. A few were hit with hammers. The result was some broken cover glass and most have cracked cells.
Some recycled roof tiles may require adjustment before use.
So, why would anyone want any of these? For one thing, they are pretty much free. For another, even if they don’t work, you can cut off the wires and make a good roof for a shed or carport. I’d reroof my 50×64 barn if a container of duds showed up at my place. The thing is, though, a lot of them do work and making a few changes in how they are used can make them practical.
First of all, don’t put them on your house. That is a contractual term of acquiring them. A shed, lean-to or outhouse is ok. One guy was going to mount them on a radio tower! In shed construction you don’t need to use a roof deck. Put up trusses or rafters (the sloping bits) and string 2×4 purlins across them at the appropriate spacing and start screwing down the panels with deck screws. This gives cooling air circulation underneath. It also gives access to the wiring so you can simply bypass one that fails with an MC3 jumper cable. No muss, no fuss.
This is how I’d do it. Just sayin’…. Solar Shed, phase one. If you don’t need a shed, use shorter posts.
Easy access to the wiring. Easy construction.
Then, connect a modest number of these low voltage modules in series as appropriate for your charge controller. In my Solar Shed project, I use strings of 21 on the 30 amp MPPT controllers on my 24v system and 4 strings of 21 for my 60 amp controllers on the 48v system to which I am transitioning.
For a barn power supply and a water pumping station, I install two 4×4 posts about head high and two shorties, with 2×4 inclines between the tall and the short. The shingles are screwed to those. 3 shingles make about 100 watts at 12v with a cheapo on/off charge controller. You can add blocks of 3 to your heart’s content.
This easy setup runs my backup water pump at the far reaches of my property. 24 volt pump and no battery. A similar setup, with battery, lights my barn.
Back at the Solar Shed, on the first 16′ section I learned to avoid the panels with delaminated edges. They are trouble. I did not put up any with broken glass, but accidents happen and I have a broken one. It does not leak and it makes electricity. Because I have access from below, I have been able to jumper out two of the delaminated ones that quit. Their bypass diodes should have done this automatically, but it seems the heat was not good to the diodes. A $20 infrared thermometer gun lets me check for hotspots underneath.
The second 16′ section has had no failures. The new 38′ section, so far, does not have a single panel that does not contain cracked cells. Want to know a little secret? As long as the silver strands are intact, cracked cell perform better than whole cells? Will they last? Who knows. Live for today!
Phase 3 of the Solar Shed in progress, as of last week. The big panels are for the Solar Yacht project hardware evaluation. Yeah, a Phase 4 is planned.
Live for today! Phase 3 of the Solar Shed in progress, as of last week. The big panels are for the Solar Yacht project hardware evaluation. Yeah, a Phase 4 is planned.
Is it practical? You decide. I charge my fleet of two electric farm vehicles, reworked golf cars. They allow me portable electrical and mechanical power over the entire farm. I run lights and tools at the solar shed, even a 2hp air compressor. I welded up the solar jalopy with this power. All construction on the shed was done with solar power (the first section power came from my solar boat). A line goes underground to the house to the emergency power circuit I had for the generator and battery backup, so my lights, office and kitchen are powered by these crappy plastic roof tiles. That’ll be 11KW of cheap plastic power when the current section is done, which means free air conditioning this coming summer!
Take your solar power with you with an inverter-equipped solar-charged electric farm jalopy.
Building the bridge to nowhere with portable solar power.
In the unlikely event that all of the panels quit, I’ll still have a useful shed with a free roof. There are plenty of others who dragged these home. How are you using them? –Neal
You could void your warranty doing this stuff
It’s a beautiful, cool sunny day here in NW Florida and you’re right, John, you can knock a hole in a solar panel and it’ll still work. Just don’t try it with a hammer, because there is a tough plastic layer under that glass and another on the backside. You need to be forceful to get a hole. I started with a Suntech STP280 that got hit with a tractor. Yup, that’s a busted one!
The frame is bent, the glass is cracked, the J-Box and all the wires were ripped off, the cells are cracked and it has been left out in the weather for a few years. I soldered on some wires and new diodes, then I took it down to a safe place and wired it up to some batteries on the solar jalopy. It was making a decent charge
I had a little test in mind.
So I shot it with a .45 pistol and it was still making a charge.
So I thought I’d try to make a bigger hole with a 12 gauge “ring load”. Nice, but no change. So I went with straight bird shot and that was better. Then I backed up and gave it some more bird shot. Then I shot it some more with the .45. Hey, I could go broke on ammo before this thing quits!
Since I was out of ammo, I unhooked the batteries and connected an offroad driving light to it… it still works!
Now it is really busted up, but still runs. Hey John, is this still under warranty for output?
Now we know. Look for test results under the “Inquiring Minds” post.
By Neal Collier
Here we go again. Hurricane Michael is projected to hit our vicinity as a Cat 3 storm. Get ready everybody!
Hi John, John, you live in a glass tower, but out in the neighborhoods you can hear the generators buzzing after a hurricane has taken out the lights. 200 watts for the fridge and 50 watts for a ceiling fan and they’ve got those darn 3500 watt generators blasting away at 3600rpm. Dumb. Well, maybe not dumb, they just don’t know any better.
At my house, the ceiling fans have a slight buzz from the inverter in my backup power system, but I can’t hear it because I have the windows open and hear those generators a quarter mile away at the neighbor’s house. Listening carefully, I can make out 3 or 4 of them. Most are those loud, cheap ones from Home Depot or Lowes and most people don’t realize that you have to change the oil in them every 25 hours (50 hours for the better ones with a filter). That’s an oil change every day or two! Cheap air-cooled engines use a little oil, too. Do people buy a case of oil and some filters when they go out and buy 2 cans of gas in preparation for the storm? Nope.
After about 3 days the generator will probably quit, assuming enough gasoline has been found to run it. If it has a low oil safety shutoff, like most Hondas, the homeowner will scratch his head and wonder why the generator won’t run anymore. If he checks and adds oil, he will be back in business. A lot of engines do not have the low oil shutoff and they will soon die a horrible death.
That assumes, of course, that the owner bought enough gas to keep it running. How long will 2 cans of gas run a generator? Not that long. Maybe a day, depending on model and load. Try buying gas after a hurricane. I know of exactly one gas station with a backup generator. Some will have power and some will rig something up. Back around 1960 I saw a gas station owner running a gas pump with a Maytag gas washing machine motor. Yes, Maytag made gasoline-powered washers! The owner took cash for the gas. Who has cash today? Credit card readers and ATMs don’t work without power. Oh, and every one of your neighbors will be in line with you, so you will be spending some time getting those two gas cans refilled. Maybe you need more than two cans.
Don’t think I am knocking gas generators, here. What I am knocking is how they usually get used.
One of the most perfect home power systems ever made, made before power lines came to us country folks, was the Delco-Light power system. Everything in the house ran on (usually) 32 volts DC. When the batteries got low, you started the generator (some models started themselves) and it ran until it ran out of kerosene or gas (they’d run on just about anything) or the batteries were charged. The engine was a low rpm machine that would run just about forever. I have a half dozen of them and none are worn out. Moreover, engines have an operating range where they are most efficient and that is with a good load on it. A fridge and a ceiling fan do not load your generator at a point of high efficiency and, remember, it takes a certain amount of gas just to buzz that thing along at 3600 rpm, even if there is no load at all.
The Delco-Light power system. One of these used to power my blacksmith shop. I love their battery rack plan for those 2v cells.
So why do I seem to be drifting off subject. I’m not, I’m just setting the scenario for you to do a modern recreation of the Delco-Light to power your AC world, use less fuel and make the night a quieter place.
Here’s what you do. Take appropriately sized inverter/charger, a bunch of batteries and add them to your generator. (If you want to add in some solar panels, then good for you.) You can have the inverter wired in through a transfer switch or you can put a plug on it and plug it where you would have otherwise connected the generator. Now take the output of the generator and connect to the input of the inverter. 4 golf car batteries (I prefer 24v configuration, but 12v will do and your car can be the generator in a pinch) will run your lights and fridge for 24 hours. There’s probably enough power left over to fire up Mr. Coffee to wake you up and nuke something from Mrs. Stouffer’s kitchen to fill you up. Run the generator in the morning before going to work (or before you begin removing the tree from your roof) and again a bit in the evening, as needed, maybe even getting a little TV or A/C time in, too. The generator will run under load and not for many hours. Now you only have to change the oil every week and maybe the power will be back on by then.
There is a security side to this configuration, too. After Hurricane Katrina, many people in the city were afraid to show any lights and run the generator at night because predators would know where there was somebody with food, light and comforts. The generators were ok in the day because there was lots of activity to mask the noise. Do NOT run the generator in the garage…it will kill you. If you don’t want it stolen, chain it to the tree in the backyard when it is running and put it in the garage when it is not. BTW, a padlock and a piece of chain should be considered a standard accessory if you buy a new generator. DON’T refuel when it is still hot. Buy some extra oil and get more than 2 cans of gas. At the end of the season, put the gas in your car so it won’t sit until next season and get stale. No-alcohol gas is best and running the generator dry by turning off the fuel valve or just running the tank dry will save your carburetor from an early death.
Just some things to think about.g Update: Michael went east of us and just made an awful mess from the coast up to Georgia. Hopefully the rebuild will include solar, as happened with New Orleans after Katrina. Unfortunately, some areas were so devastated there was nothing left for solar to power.
John and I have been discussing options and strategies to have a stormproof shelter incorporated into your home.
By Neal Collier