Troubleshooting II

Last time I wrote of dealing with one of two recent issues that have come up in my system. Michael C. wrote to me regarding an alternative to the water heater dummy load to test or calibrate inverter power. He pointed out that the air handlers—the box in the hall closet– of heat pump and a/c systems usually have a big resistive heating coil built in. When systems get replaced the air handlers get chucked, except maybe the A coil, which contains copper. An old air handler or two could make a dandy air-cooled dummy load and maybe even for free!  Add the power controllers from ebay and an ammeter and you are ready to burn some kilowatts.  Thanks for the idea, Michael.

The other problem I mentioned was that the slave inverter of my pair of Sunny Island 6048 inverters was slamming off and on when the temperature got around 27 degrees or below.  These were bought at auction with no warranty, so I am on my own, here.  Intermittent problems can be maddening.  When I worked in computer service I might drive across 3 states or fly across the country only to find things running just fine when I got there.  You can’t fix it when it ain’t broke.

To that end, I’d try to break it.  Computers used to be real fussy about temperature, so I might hose down the circuit board with freon or a heat gun to see if that would affect it.  Or maybe start wiggling cables. This is where I started on my inverters.

After being disappointed by a lack of error codes in the built in diagnostics, I pulled the covers on both inverters.  The inverters are in a cabinet that barely allows the covers to be removed, so it involves a prybar to deflect the cabinet a wee bit.  Naturally, the power was disconnected as I looked for dark spots on the circuit boards and took a wrench to the huge DC power cables coming in from the battery bank.  No problems there.  I unplugged and replugged every connector to exorcise any minor corrosion that might be there.

Something was missing, though.  It appears that there are components on the back half of the chassis and it looks like you can only access this side if the entire inverter is removed from the cabinet.  While I admire the packaging  effort that DC Solar went to in designing this system, it has some maintainability issues.  I am NOT going to take those inverters out unless they are stone cold dead.  I noted that the circuit boards have 2 connectors marked FAN and I suspect that neither fan is working on the master unit.  The fans are on the back side, naturally.  There is a hot smell when the generator is running to equalize batteries, I suspect as a result of no fans.

I can deal with that to some degree with external fans.  Furthermore, the unit derates itself if it gets too warm, so it isn’t hurting anything.

As for the principal issue, 27 degrees does not happen a lot in Florida.  I think we have had 2 nights at or below that, so for now, I will just toss a shipping blanket over the outer cabinet to hold in the self-generated heat a bit or even put a small heater in the cabinet…even a light bulb.

I know that sounds like a cop out, but there’s the old adage, “If it ain’t broke don’t fix it.”  Yes, I know it is broke, if only a little bit, but it could be a lot worse.  The oft-ignored motto of the medical profession is, “First, do no harm.”  Getting those mostly working inverters out of that tight cabinet would provide all sorts of opportunity to do inadvertent harm and those are really expensive inverters.  In the meantime, I will keep watch on the forums and see if someone comes up with a solution.  Sending the inverter to the factory with a note that says it won’t work below 27 degrees will not likely result in a fix and will result in lots of postage for a heavy package that might get even physically broken in shipping.

So let’s modify the old adage.  If it ain’t really, REALLY broke, don’t fix it.  (Unless it is under warranty.)


Fountain at James Houston Jones Park, Century, Florida

A Little Late

Hopefully, not too late. Last time I promised a series on emergency backup power, with and without solar. I also promised it would take a while because I’d need to take some pictures and make some drawings. Writing a column isn’t just writing. Writing is easy, like running off at the mouth, but people like pictures. And a picture is worth a thousand words.

We’ve had a good year, from the standpoint of hurricanes.  Summer was cloudy and rainy, which are not good for solar, but it was relatively calm.  Calm in Florida.  Folks that got floods and tornadoes will disagree and they may find the backup power series useful, too.  When I get to it.  Now autumn is here.  September is great.  It stops raining, we have lots of sunshine and temperatures drop into the 80s.  Love it!  But now, suddenly, the hurricanes are popping up.  One just trashed Puerto Rico and now there’s another brewing.  After practicing on Cuba, it appears to be heading to Tampa.  Oops, now the cone includes MY house!  OK, that is getting personal.

I promise that what follows will be rambling and somewhat incoherent.  I have been distracted recently, but there there may be a useful nugget in here.

It started last Friday.  Andy, my brother, usually comes up on his day off.  We trade books , shoot guns and or ride motorcycles (instead of working on the blog).  He knows not to come too early as I am not a morning person, but I do make an effort to get up before noon when he is coming up.  So, I puttered around and he didn’t show up.  I tried texting him, but a DR650, his recent ride in the eternal quest for THE ONE, makes a bit of noise and vibration and it is not uncommon for a call to be missed.

I puttered around until after lunch and decided I would venture off to the museum, in Century, where one of my solar installations was having an issue.  I decided I needed some wind in my face, like an old dawg with his head out the pickup truck window, so I went to pick out a motorcycle.  The solar-charged Zero motorcycle is a hoot and costs nothing to run, but I felt I needed some rumble, too, so I picked the barely-muffled Shadow ACE. 

I looked for a meter to take for troubleshooting, but I could not find one.  I swear, I think the electrical field of my 400 solar panels has disrupted the time and space continuum, as tools just disappear for weeks at a time and then mysteriously reappear on my workbench.  Anyway, no meter.  Oh well, I’m a pro.  I can improvise.

So, I roar off to the park to check out the lion’s head fountain that is no longer flowing.  This is a direct drive system with no battery or electronics.  Dirt simple.  I check and there are no leaves on the panels, which are mounted inconspicuously on top of a trellis.  That leaves the pump or wiring or a bad panel.  I suspect the pump and have both a spare and an external test pump.  I really don’t want to have to swap the submersible pump, because I’d have to siphon off the pool, open up the plug, fish wires through for the new pump, drag 100 yards of hose to refill the pool and buy chemicals to keep the pool from turning into a swamp.  Algae would give the poor lion a green beard beard and we can’t have that.

Assured that the panels were clear, I went behind the fountain and connected the external pump to the wires and nothing happened.  Hmmmph.  I bumped the wires together and there should have been a  tiny spark, but there was none.  Then…did you ever test a 9 volt battery by touching it to your tongue?  Well, yes I did and there was only the slightest tingle, like a bad 9v battery.  Well, well well.  Oh, before you try that, be aware of what you are testing.  I have some panels that put out 90 volts, which would turn a tongue into fried bacon.  These two panels in series in bright sunshine might make 12v and are pretty mild.  The average full size panel is 36 to about 48v, so don’t test them that way.  Find your meter.

The fact that I got a slight tingle, along with a visual inspection pretty well assured that the wires were intact.  The squirrels had not gnawed anything.

The solar panels on the system at the museum’s blacksmith shop are shiny new things that Roberto sent from Sun Electronics and are working great.  The ones on the fountain were used and abused.  I did not bring the prettiest ones because I am planning an expansion of the Solar Shed and need these solar shingles for my roof, preferably making some additional kilowatts.  Net result is I am going to have to not be so frugal and grab a replacement panel from my private reserve to replace the bad one.  No big deal, but I’ll have to go back and get the truck and a ladder, etc.  Oh, by the way, when I got home the meter had returned to my workbench after I had taste tested the solar panels at the park.

Back at the house, I started gathering stuff to go get the lion flowing again and the phone rang.  Maybe that was Andy.  He was a few weeks from retirement and looking forward to riding all over the country on his various motorcycles.  Maybe he was ready to declare that the Suzuki was going to be the perfect ride. You know, THE ONE.  Nope.  He had been riding a back road in the next county over and had slowed to ease around a mud hole.  A tire slipped in the rut.  He fell off, broke his neck and died in an instant.

So, I’ve been a little busy with family stuff the past week.


Fun With Microinverters

What is a microinverter and how can you use it?

You have solar panels and you want to do something with the DC power, you’ll often need some kind of inverter. The microinverter was designed as a grid tie inverter to pump your solar DC into the power grid. There’s more.

In the beginning there was a thing called a synchronous inverter. It was a big box on the wall that took all of your solar power and pumped it into the power line. It was a grid-tie inverter, but nobody had come up with that catchy term. It could stop or run your power meter backwards. Nobody could really afford a bunch of solar in those days, so the power company didn’t catch on and charge a bunch extra.

Then somebody came up with putting a wee grid-tie inverter on the back of EACH solar panel. First time I heard of that I thought it was a really bonehead idea. They have evolved and from what I see, these are the number one way of doing grid-tie. I think it probably boils down to labor cost. I had a case of them to play with and will try to pass along some of the fun things you can do with them.

Each module (sometimes it is 2 modules per micro) gets a microinverter bolted to the back. The racking goes up on the roof. Then a long black cable with funny connectors along its length is spread out along the roof. A pass thru is installed to get the cable through the roof and it connects to a breaker or cutoff at the house’s panel or someplace handy for the Fire Department to cut the power.. Finally, as you bolt the panels into place, you plug the connectors to the microinverters. Ta da!

Yeah, there are inspections and you have to make arrangements with The Power Company. Often, TPC will make you wait a month or two before you can turn it on, will make you pay for insurance, charge a bunch every month for the capacity of your system and then give you just a little money for your Kilowatt Hours or KWH. Or, you could get lucky and live in a net metering area. Then grid tie is a good deal.

Let’s say you are among the lucky few to be in on the net metering gravy train. What happens when the lights go out? Well, they go out. There’s no storage. Some of the big box GT inverters and some of the latest micros can provide daytime islanding, or power in your house at a vastly reduced rate, probably to account for passing clouds and such. It is enough to keep the fridge and a few lights on.

So those are the basics. What if you do NOT want to go with grid-tie, but have a case of microinverters and a pallet of solar panels? That’s where it gets fun.

A case of Microinverters. More fun than a barrel of monkeys.

If you root around way back in the blog, you may still find some stuff I did with a/c. I’m in Florida and a/c is very dear to me. Watching the weather reports at night, I think a/c is becoming important to everybody else! Under the hood of your outside unit, there is a contactor or relay that uses the 24vac signal from your indoor thermostat to connect the 240 volts to run the compressor. If you connect the AC side of your GT microinverters to the compressor side of that relay and size your solar source to just a smidgen less that what the a/c uses the solar power will be directly consumed by the a/c and none will flow back to the grid. No need to involve TPC and pay their fees. This works. I had both of my compressors heavily instrumented and had all the figures. There are downsides to this method. When the compressor switches on, there is a mandatory 5 minute delay before the micro kicks in. I improved performance by just running the smaller upstairs unit pretty much all the time during the day. Another problem is those dang clouds. Forget that “Sunshine State” crap. It ain’t so. And then it didn’t work at all at night.

Under the hood of one of my A/C units. I put in meters to prove the mods were working. The white box is a “soft starter” which makes starting a heavy load easier for the inverter. These are not cheap, but are worth having..

The Mark II version of this system DID work at night. The Enphase inverters will limit power to what they can handle. There are some cheapo Chinese GT inverters on Ebay that will blow up if given a high current source because they do not limit. SO, I connected the solar panels through a charge controller to a stack of golf car batteries, like the Sun 230 that John and Roberto sell. Actually, I connected a lot of panels to charge the batteries. Then I connected the batteries to the DC inputs of the appropriate number of micros. NOW, the sun was not wasted when the a/c was off, it went into batteries. And because there were batteries, they worked when running the a/c at night!

The aforementioned Sun 230 batteries…more good cheap fun.
That’s the idea! How’s that for summer power usage?

That big black cable that connects the micros is awfully expensive. If you find a deal on a sack full of micros, make sure they come with the “drops” as they are called. The cables are not only weatherproof, but they also contain a communications channel, which can enable another neat trick. Let’s say you want to counter power use in the entire house, but not go grid tie. There are several companies that make communications controllers that can sense the overall flow of power and throttle back the flow before any can escape to the grid. Your meter will rat you out if you grid tie without approval. If that happens, the big white truck comes and then you got some ‘splaining to do, like Lucy Ricardo. Connect the AC side of the micro to a 240v breaker in the panel and run the sensor coils from the main lines coming in from the grid to your communications controller. The battery trick should work here, too, but unless you have micros with the limited AC backup function it is still not a good solution for the grid failure condition. If you are buying batteries and charge controllers you are better going ahead with a hybrid system that I go on about so often.

There’s another really bonkers trick you can try if you have a battery hybrid or off grid system. I was one of many of the people who bought the bankruptcy inventory of DC Solar company’s solar trailers. Complete system in portable format. Some of these guys must have terminal disease or be just plain crazy with some of the stunts they’ve pulled. Some blew up some expensive hardware and some came up with some cool hacks.

What happens if you have an off-grid power system and connect a string of microinverters to the output of your inverter? The micros think they are syncing with the grid. Well, if you have the communications system with the limiting sensors the micros will help out with your load. Say, you could have the 12kw inverter that came on the trailer just idling while the micros sync to it and provide all the power for your 3kw a/c and the 500 watt fridge. But if you don’t have the limiter or if you have the older, stupid micros, they will actually backfeed through the inverter and charge your battery. There is some possible peril here, depending on battery and system size. As the battery approaches full, the regular charge controllers will back down and the only charging or overcharging will come from the micros. With the size of the batteries we got with our trailer systems it is unlikely you’d have enough micro capacity to damage anything, as long as the micro capacity is smaller than what the transistors in the inverter can handle. Use this trick with caution.

What I have not yet come up with is a really good way for someone like my neighbor EJ who has a really, really bad deal on a grid tie system full of microinverters to fully utilize his solar capability without spending a lot more money. Best I can come up at this point is to get the communication controller, shut down the grid export and to tell TPC what they can do with their GT meter and associated monthly fees. By scheduling most of his heavy power use during the daytime he could make a serious dent in his power bill.


EVs and Solar Charging

Electric Vehicles (EVs) have been around over a century and have been very popular and practical in some areas. In other areas, not so much. They are perfect for forklifts, golf cars and neighborhood vehicles. Even delivery vehicles with a fixed, predictable route.

Electric automobiles were tried early on and their usefulness was limited. The same goes today, but they are becoming more practical. Good thing, because the government seems Hell bent on forcing everybody to get one.

There are a problems with everybody getting one. They can’t build them fast enough. There isn’t enough copper and rare earth materials for the motors. We don’t have enough lithium and cobalt for the batteries. Not everybody can afford one. Not everybody wants one. On the other hand, nobody wants to pay $4-5 a gallon, or more, for gas.

Hurry up and wait! Standard government procedure. We have the materials in this country, but the government won’t let the miners mine. There needs to be a coordinated effort to get this done if we are going to do it.

Then there is the other problem. How do we find enough electricity to charge the cars when many parts of the US and other countries can barely keep the lights on? They shut down the coal plants, knock down the hydroelectric dams and turn off the nukes. How’s that going to help? I guess we’ll just have to do it ourselves. I do.

I own 4 electric vehicles, with more on the way. No electric road cars, mind you. My most-used road vehicle only has 280,000 miles on it and it just got a new fan belt, so it’ll be a while before I need a new car. I figure if they get a Supercharger station at every Interstate rest area and Cracker Barrel restaurant, a 400 mile battery car will be ready for prime time. They exist, but they cost more than I am willing to pay.

In the meantime, my farm and recreational EV fleet is charged by solar…very carefully.

There are the two electric trucklets, proof that someone with idle time and a torch should not be left unsupervised. The gray one, is based on a Yamaha G19 golf car (not cart) and the other (red) is based on a Zone NEV. Previously I had full sized pickups for farm chores and these jalopies are actually better than the pickups. These have been fitted with a forklift plug. They can plug into a standard 48v charger, running from the main solar power system’s inverter, or they can plug directly into the solar power system’s battery stack. If not in use, the buggies can each contribute another 10kwh of storage to the system.

The ZERO electric motorcycle would be great in town. Out where I live, with a limited range of maybe 50 miles, I can go the 32 mile round trip to the bank or the barber. I guess that’s fine. It has to plug into AC from the solar power system.

Then there is Sun King, the electric launch. It is solar powered, so it pretty much takes care of itself. I have traveled thousands of miles in this boat! When stored in the shed, there are three panels outside and a dedicated charge controller to keep it fresh. Sun King can serve as a backup power source, with 7.5kwh battery and 5kw inverter aboard. Maybe I should charge the Zero with the launch!

The bike and the buggies are my main concern and there are special considerations with my present system capacity.

First, the plug-in golf car charger and the motorcycle both have something in common with your new Tesla’s 120v charge plug. They connect to a standard outlet and they pretty much suck out as much power as it can give. That means you can’t do much else with that circuit when a vehicle is charging. I have the motorcycle charger on a different circuit from the buggies so they can charge at the same time and only one charger for two buggies. I only have two 120 circuits in the shop, so forget using the air compressor or other big load.

Then there is the capacity of my solar source. Because the motorcycle never completely turns off, I leave it plugged in all the time. However, I have it on a timer, plain old appliance timer, so that it charges only during the day when there is usually plenty of power. But there are cloudy days and, for some reason, that’s when the wife likes to run the clothes dryer. You get the central air, Man Cave a/c and the clothes dryer going on a cloudy day and you may not get the battery bank topped up if charging buggies. So I charge buggies when the sun is out and the dryer is idle.

Another buggy and an electric aircraft are in the works, as is a solar-powered yacht. The yacht project has languished, but when the airplane is finally delivered it will need to be charged. My plan is to park the yacht next to the hangar and get started on the yacht’s power plant. Two birds with one stone. Shared resources. I can’t use both of them at the same time, ya know.

Now what if I broke down and bought an EV or PHEV (Plug-in Hybrid)? Yeah, I’ve thought about that. For MY driving, I’d use the 120v cord. For near errands I would just as soon go on the ebike or the big Honda. My wife, on the other hand, is a goer, but there is a good chance she could get by with the 120 cord. The power rate of the 120 cord would not require major system upgrades, though a few extra panels to help out on cloudy days would be desirable.

If I were still working, I’d have a commute of around 100 miles, daily. I think now we are talking PHEV or going to a faster 240v charger. That’s where it gets tricky, because all of this power is coming from solar panels, batteries and inverters. Either that or there’d be a heckuva power bill.

First, I’d need more power source. As it happens, I am in talks with John Kimball about getting another pallet of solar panels. Batteries? As long as I could charge in the daytime I’d be okay, but most people work day jobs! The extra panels could be arranged to maximize early morning and late afternoon charging and, if I had a 400 mile car it would work out, at least in the summer. In winter, a trip to the Supercharger station might be needed once or twice per week.

Then there is the matter of inverter capacity. As it happens, I have a backup inverter that could supply the 50 amps of 240v to a fast charger. The fast charger would use more power than the house! What does an extra 10-12kw inverter cost? It adds up.

Oh dear, don’t be THAT guy.

So, yes, I am using solar for vehicle charging and making expansions for the future. As far as a new car goes, I think I will opt for a PHEV. It may be the best of both worlds. A Ford Escape (ugly little car), for example, could make it to Walmart without the engine starting. It would run the engine most of the way home. A trip to the bank or barber would run 100% on sunshine.


Used Panels?

Junk yards like to say that all cars run on used parts. It is true. The same is true of solar installations. There’s a solar farm being built just up the road and there are 180,000 panels sitting in piles in the field. They are soaking up dust, dirt, rain and humidity while waiting to be mounted. And they’ll work.

180,000 450 watt solar modules in a field. Just kinda takes my breath away.

What about panels that have been installed and running for 5 years? They are likely to have a slightly reduced output, but they are also very likely to be pretty cheap, compared to new ones. Which is the better deal?

Personally, I have bought new, latest, greatest panels for my boat projects to get the most watts in the limited space available. For my house, though, I have hundreds of used, sometimes abused panels. The last panels I installed were on my ground mount. Not sure how old they are, but they were in service, out in the elements since 2015, and they work great Others, the ones that were literally thrown off the roof when taken out of service, are mostly still running fine.

Neal's Solar Shed
Nearly 400 panels in this view. About a dozen were bought new.

Good news for folks considering buying used modules, a recent report says that panels made a few years ago were made differently and do not degrade as quickly as the newer panels. Don’t worry, neither is likely to be a problem. The report says the big difference is in the layer of clear sticky stuff between the glass and the silicon. Just like the plastic headlights on cars, enough time in the sun and they start to discolor. The layer in a panel is so thin that you just don’t notice it. Frankly, the solar cells don’t notice it much, either.

After a dry spell, John is once again finding scads of used panels and new-old-stock surplus. Don’t be afraid of them. They’re good, cheap watts.


One Moment, Please

I called John to fuss about the website and email. Yeah, there’ve been problems.

In his John’s Blog, you never know what kind of crazy stuff you’ll find, but there’s really useful info, too. He mentioned a recent email blast and I didn’t get one. I live 700 miles from Miami, so it isn’t like I can just drop by and see what specials he has going or what kind of leftovers might be in the back corner of the warehouse. I rely on the emails for that info. If you did not get a recent email from Sun Electronics, do what I did. Go to the main page and sign up anew. Databases get corrupted and stuff just evaporates with computers. Freshen up your listing. John has some really great deals on the way.

Then there is the trying to get the page to come up. You can’t find deals and I can’t write blog if we can’t get in. There has been a problem, lately. I observed the page as to how it did not work and it looks like a DNS problem. When you type in or another site, it calls up the Domain Name Server, or DNS, to see where to go next. If that is broken or a cable is down, you don’t get to the site. If at first you don’t succeed, try, try again. Research Rich, the IT guy du jour, says the signal is bouncing all over the world before it gets where it needs to be. It is being looked into.

IT guys and gals and webmasters at Sun Electronics are like drummers in rock bands. Lots of turnover. I don’t know if they die or just wander off, but the new guy has to figure out what the last guy did or did not do. I have put word in that I want to see more tech details and data sheets.

The phone usually works, though, so give John or Roberto a call if you need anything.

While I was on the line with John, I checked on what inverters he regularly maintains in stock or can get a quick drop ship on. I have been getting questions on setting up a backup or solar hybrid system, with details on what hardware to use. AND I have been wanting to answer those questions with an article with specific hardware that I know will do the job. Watch for that soon…if I can get back into the website.–Neal

What Voltage Should My Battery Be?

As a rule, the Direct Current (DC) side of an off-grid or backup home power system will be 12, 24 or 48 volts. Some equipment is available for the archaic 32 volt system and there are maverick higher voltage systems. I think most of you will best be served by one of the big 3 systems because you have better availability of hardware at a better price.

First, let’s understand power. Power is measured in Watts. It is calculated Power= Volts X Amps. For some odd reason, this is expressed in the industry as P=E X I. Go figure.

Ok, so from that formula, to get more Power, you need more Volts or more Amps. More amps will require heavier cable and careful management to prevent losses and meltdowns. It will require bigger batteries or more in parallel. More volts will require more batteries or cells in series to achieve, but you don’t have ridiculous amounts of copper to carry the current.

Big amps? Keep the connections tight or bad things can happen.

So, is there a rule of thumb as to which system voltage you should choose? Let me propose one. I like 00 gauge cable. Triple-ought is harder to find terminals for and 4-ought (0000 gauge) is difficult to work. Depending on which chart you use, what the temperature is and how long the cable is, you might see double-ought cable rated from 175 to 283 amps. I lean toward the higher number for solar use because my cables are reasonably short and don’t get much above 100 degrees. Let’s call it at 250 amps for the sake of a discussion.

250 amps X 12 volts = 3kw

250 amps X 24 volts = 6kw

250 amps X 48 volts = 12kw

So here is what I propose: If you need more power than a 00 gauge cable can carry, maybe it is time to step up the voltage.

Batteries are connected in series for more volts. Parallel for more amps. Make sure you have enough battery for all the amps you want to draw and shoot for an average draw of around 1/20 of the battery’s amp-hour rating.

There are other considerations. Running a 12v system with “12v panels” can be very expensive because the so-called 12v panels are expensive. They are a specialty item, usually targeted to the marine market. If you own a boat, then you know boat stuff is expensive. You can avoid that penalty by using standard 60 or 72 cell panels with outputs in the neighborhood of 40 volts by using an MPPT charge controller. That stands for Maximum Power Point Tracking. Most MPPTs are good for up to 150 volts input, though I have a Midnite Solar controller that can handle 250 volts. Some MPPTs of dubious Asian origin might handle a single 60 cell panel. Read the spec sheet carefully.

With charge controllers, you’ll get back to the P = V X A thing again. Most MPPT charge controllers will automatically adapt to the battery voltage. A 60 amp charge controller is good for 720, 1440, or 2880 watts, depending on battery voltage. If you are shelling out $7-8 hundred bucks for a high quality controller, maybe just stepping up to the next voltage level can save you some big money.

Decisions, decisions.


That Black Box

What’s that black box on the back of most solar panels? Is it just a place for the wires to come out?

There are all kinds of panels, but the usual 60 or 72 cell module in an aluminum frame is going to have the black box. This is usually called the junction box. Yes, it is a handy way of getting the power out of the panel, but there is more to it.

If you have just a laminate, which John sometimes has in stock, you have the glass panel, but not the aluminum frame or the junction box. The back of the panel has a number of silver metal strips protruding and they are kind of delicate. You don’t have just a positive and a negative. Terminals inside the black box clip onto the silver strips and then the box is glued to the panel with silicone. Silicone helps keep the water out, too.

The typical panel has not one, but THREE series circuits of cells in it. There’s good reason for that. Poly or mono cells can be shut down by a single large leaf or bird splat. Sad but true. You don’t want your rooftop solar to shut down because the chimney is putting a little shadow on one of the panels do you? Of course not. So, they put three circuits in there, hoping you only lose a little power if you get a little shade.

Inside the box, there are some diodes. These are like one way valves for electricity.. They won’t let power flow backwards, but if a string within a panel is blocked or if the entire panel is blocked, power from other panels in series can use the diodes to work around the panel that can’t work and let the other panels in a string get some work done.

Usually these are not a maintenance item, but things happen. Lightning can burn out a diode. Heat can get them, too. Once in a while, like on the old solar shingles on my shed, somebody makes some poor choices and undersized diodes are used. A bad diode can cause hot spots and eventual panel failure. If you ever notice that one cell in a panel is brown or unusually hot, shut it down before it breaks. It probably has a bad diode. Fortunately, this rarely happens.

Crazy things can happen, though. I was once given a panel that had gotten too close to a tractor with a front loader bucket. (Actually, I think it was the other way around.) The story goes that the panel, fearing for its safety, leapt from the rack to the ground. In doing so, it left the cables and junction box behind. That left four shiny strips on the back of the panel. I could have just bought a new junction box. I don’t know if John has them, but numerous people sell them online on ebay. It seemed rather pointless as the glass was broken and the panel was bent, so I just soldered on some diodes that I had in the parts bin. This was not going to be installed in a system. Not even I would do something that appalling. What I did was probably worse. John and I had been having this discussion on how hard it is to destroy a solar panel. The cells, after all, are just finely sliced rocks with wires attached. He advanced the notion that you could probably punch holes in them and they’d still work.

So why not try it? There are neighborhoods in Miami where gunfire is not uncommon, but it is generally frowned upon. Not so in my neighborhood, so I got to have the fun. I proceeded to make small holes with a .45 pistol and large holes with a 12 gauge shotgun. While the power is somewhat reduced, it will still charge a battery!

I wish I could say that no solar panels were harmed in the course of these experiments.

It may seem that I have digressed, but back to the point of diodes in the junction box, the diodes I had tacked back onto the panel allowed the working and non working sections to work it out so that panel still had enough output to charge a battery or operate a car running light.

I am pretty sure that a shotgun blast directly into the junction box would be the end of the panel. Don’t try this at home.

And, yes, the junction box IS a handy place for the wires come out. Take note when ordering what kind of connectors are back there. MC4 is the “usual” but there are others that look similar, but won’t fit, or will fit, but not well enough for a safe connection. Be sure to order the right connectors so you won’t have the installation delayed. You don’t want the neighbors to hear you cussin’.


John’s Rants

John’s ranting about the shortage and price of solar modules over on his blog. He can get pretty entertaining at times, but he is also very serious. This guy wants everybody to have a roof or backyard full of solar panels.

I find it amazing that the government creates a full tilt initiative to promote solar and then puts all kinds of roadblocks in the way. It must be working to some degree. We know solar farms are going up everywhere, but even in the home and DIY market, it is getting harder to find 24 and 48v system hardware. Closing down reliable coal and nuke plants before the solar farms are running all get battery assistance is really dumb, especially with electric cars being forced upon us.

Then, once people adopt solar, they find the .gov or the power company has put some limitation in the way. California now requires every new home to have solar, but they have been promoting a rate structure that would eliminate solar. In the meantime, people in California need solar to keep the lights on, because the power company can’t seem to do so.

Good news on that front, a judge just ruled that Arkansas power companies must go with net metering and pay homeowners full retail for their excess power. Even better, no solar connection fees.

There is also potentially good news on the solar panel front. The industry notes that many solar farms will be repowering soon. The hitch is, THEY have to find some new solar panels. Nothing wrong with second hand solar. I have over 300 of them, 15 years old, out on the Solar Shed and my house is off the grid. These were not even pampered like farm solar panels. These were stomped on and thrown off the roof.

When John sells used, they are tested and graded by appearance and you get a warranty. It may soon get better than that. So many panels could be coming to market that there will be new uniform standards for grading. For example, today’s panels are made with higher dielectric ratings (how high a system voltage you can run without you getting electrocuted ) Early grid tie strings would run up 300 to 600 volts and now the commercial farms can run over 1000. That’s good to know if you put together a grid tie system with a new inverter and used panels. (Unless you live in Arkansas, grid tie may not be a good idea.) I think the rest of it is pretty much what John has done for years.

There’s my fantasy. Piles of solar.

Anyway, we may see cheap panels return IF the solar farms can get new panels. The used panels will not be these 400+ watt super modules, they’ll be the 250 watt modules. No problem, you pay by the watt and not very much. Just use more. Those 300+ solar shingles at the Solar Shed are only 34 watts each on a good day, but they add up to some serious kilowatts.

Now, if we could only get rid of a couple of dozen government agencies that nitpick us to death! Seems like I recall that in Biblical times they’d have a Jubilee. Every 50 years, everything would get reset. That’d be great. Congress can crank out a lot of laws and regulations in 50 years, but at least they would not pile up on the previous ones.

In the meantime, let’s get John outfitted with new boots and fedora. Send him out to search the land for more panel bargains.–Neal

There’s An App for That

In early summer of 2015, I was on my solar expedition launch Sun King. Cruising up the Tennesee-Tombigbee Waterway. It was raining and getting dark as I approached the lock and dam at Aberdeen, Mississippi. I don’t like to run in the rain and there are limitations to running in the dark in a solar-powered boat. Nonetheless, I pressed on. I had a rendezvous the next day. An important one. My wife and Mom were bringing supplies to restock my chips and jerky rations.

Getting through the lock was no big deal, but it was raining pretty well by the time I cleared. I turned to starboard and went looking for the channel markers to the Aberdeen marina. It turns out the LED floodlight was inadequate and the rain made it impossible to find the way. It is tricky in good weather if you are a stranger. I found a shallow spot and dropped anchor for the night. After supper, I heard a power boat go by. Local river rats always know the way.

It was a good thing I locked through when I did. By morning, the river was up 20 feet and the current was faster than my boat. Man, it had really rained. It was still gloomy, but after breakfast and coffee I wound my way through the channel and found the marina. It was still a little wet, so I tied up at the seawall to wait before checking in with the folks who ran the place. Note that despite running in the dark, fixing supper, fixing breakfast and getting underway in the gloom of a rainy morning, I still had plenty of power.

Tech specs: 1620 watts of solar panels, 6x Energizer 8v golf car batteries, arranged series-parallel for 350 ah at 24vdc. 8 kw inverter (overkill, but the 3kw I had before had died). Motor was a custom build, based on an array of Minn-Kota parts.

After 4 days of cloudy weather, the batteries may be getting low in your solar power system. Try cutting back on the loads as the panels will charge, even on a cloudy day. This day, I fixed a cup of coffee and went beach combing along an island shore in Tennessee Lake.

It would be a while before the resupply crew would arrive, so I reclined my captain’s chair and settled back for a little snooze. It had been an unsettling night with all the thunder and lightning going on. My nap didn’t last long as suddenly the gawdawfulest blast of catterwallin’ occurred and just kept on.

Mississippi has a network of storm sirens throughout the land. You can hear them for miles and if you are between them they set up something of an echo. I had tied up right under one of these infernal devices. What a rude awakening!

I survived that day at Aberdeen and the various perils of the entire 1920 miles of the trip around the big island of Mississippi. Bet you didn’t know Mississippi was an island did you? If you can drive a boat around it it is and I did so. So it must be an island.

Yesterday morning I had a jarring awakening. My phone has somehow developed the ability to be the equivalent of a Mississippi tornado siren. It doesn’t matter what the volume settings are on the phone, this makes itself heard. Yup, tornadoes inbound. I checked the radar and saw it was doing the usual split up the river that is our county line and the other river that is our state line. I don’t know why, but the tornadoes like the river valleys better than our ridge. I’m ok with that and I rolled over to catch some more zzzzs, while Pensacola got thrashed.

Later I got to thinking about phone apps that might be useful for solar. Since I have gone fully off grid, the days of endless gloom and rain have begun. I have been going through some neglected areas of my system to try to squeeze out a few more watts.

At the planning stage, I found Suncalc which shows the sun angles at different times of day and in different seasons. If you can’t site your solar panels to the traditional south orientation, Suncalc might help you find a good alternative.

At the building phase, there is a app that lets you use your phone as a level or clinometer. Note that not all phones have a sensor array. I hold on to old Androids to use as tools if they have sensors my regular phone does not. If you can play video games by tilting the phone, you have the sensors that will let you mount your supports vertical and horizontal and then set the panel angles.

Some phones have a magnetic sensor that will drive a compass app to select your direction of the array. If you don’t have that, some compass programs will work with the GPS in your phone if you walk around a little.

There are also a number of apps to predict your solar insolation or available sun power. Some are purely theoretical and some are somewhat interactive. Solar Radiation Calculator decided that at my location I should receive 2920 kwh per year, per square meter, from the sun. Given that panels in perfect alignment are good for around 20% efficiency, I need a number of square meters. That one is probably best for the planning phase. Another app i tried, PV Solar Forecast, scans weather service radar and cloud maps to guess how many watts your system will give you. I am still learning this, but it looks like it is assuming you have a grid tie system. There are some calibrations available, so this one might be useful for rough estimates of the day’s performance.

Not a lot of watts, today. We should catch up over the weekend.

Now, for even more accurate info, you will find there are apps that will talk to your charge controllers, inverters or grid tie system to get the direct scoop on things. There are even aftermarket wattmeters that your phone can monitor with Bluetooth.

Try roaming the Apple and Play stores for apps. Usually, there are free ones you can try. These often come with reduced features and annoying ads. If you find an app you really like, paying a very few dollars can make those ads go away and bring you some new features.

Let’s see now, earlier, the app said I was making 400 watts. says I have perked up to 1.6 kw, and by the end of the day as the rain clears I’ll still have clouds and low output. Not a good solar day, but I already sort of knew that. Looks like tomorrow will be better. Good, my batteries need those kilowatts.


GS 4048 Hybrid inverter

Louisiana Screws Up Net Metering

Don’t Worry, We Can Fix This

After Hurricane Katrina, solar power took off in New Orleans. Long nights without power left folks wanting a little more control of their situation and rooftop solar took off.

How much of that was actually usable when the grid is down and how much was grid tie? I’m betting there was a lot of grid tie.

Nothing wrong with that, especially if you get real net metering. Figure up all the power you made and how much of a net surplus or deficit you had and money changes hands at the retail rate. In other words, if you used 1000kwh (kilowatt-hours) of grid power and the rate is 13 cents, then you sent the power company a check for $130. If you made 1000kwh more than you used, then the power company sent you a check for $130.

This is a really sweet deal, if you can get it. A few weeks ago, the Show and Tell post featured a Texas system owned by Daryl and some add-ons to a South Carolina system owned by Courtney. Both have that deal. Apparently, Louisiana has had that deal and now they want to change it. So much for the payback calculations.

I’m just going to use some round numbers, here, but they’ll be close to the real deal. Under the new deal, that begins with the new year, if you use an extra 1000kwh, you’ll still pay $130, but if you make an extra 1000kwh, you will get $34, based on the wholesale, or “avoided cost” rate the power company pays.

Ok, it’s actually worse than that. If your system makes an extra kwh today, you get your 3 pennies credited, but then tonight when you use a kwh to watch the evening news, they are going to charge you 13 pennies for the electricity they bought from you for 3! It cost you a dime for your own power! Figure, too, that a lot of power companies have extra connection fees for solar producers.

This puts you where I am with my power co-op. Florida law has been that the “regulated power provider” has to do net metering. As a co-op, however, they are exempt, so they make it foolishly expensive to connect grid tie solar.

Fret not, my friends, for there is a way for you to have your solar AND keep the lights on after a storm. It is called HYBRID solar. You will probably have to reconfigure your solar strings and buy some more gear, but what you will end up is not only a more versatile system, but one that makes more economic sense, as well.

If your grid tie system is in the most basic form, you have a number of solar panels in series connected to a string inverter. If this is your system, you remove the Sunny Boy and separate the seriously high voltage string(s) of modules into groups of, say 3, to get the voltages you need for charge controllers. Yeah, you gotta buy charge controllers. Maybe you only need one if you get the monster 300 amp Flex Max.

The output of the charge controller(s) goes to your new battery bank. The size of your battery bank is going to depend on how long you want to keep the lights on with solar power. If you have a lot of solar and a little bit of battery you can cook the life out of the battery in a hurry. A Flex Max can be turned down to accomodate the battery’s well being, but then you aren’t using all of your solar. I know it hurts to write that check for a big battery stack, but you won’t regret having it.

Now, you need a hybrid inverter to replace your string inverter. If you were doing your grid tie connection via a hybrid inverter to start with, then congrats. The “hybrid” inverter is called that because it can do grid tie, it can act as a standalone inverter, it can act like a UPS, it can charge batteries and sometimes they have other tricks.

Outback GS 4048A
Outback GS4048A

I’ll tell you how you need to connect this new hybrid inverter in a moment, but you need one more thing. You need a transfer switch. This allows your inverter to connect to SOME or ALL of your house’s circuits. The simplest thing is to use a whole house transfer switch, which of course may cost more and will require that your new hybrid inverter be hefty enough to handle all the loads. You may think that you can pick and choose what you have running to stay within the inverter’s capabilities, but you will likely have someone in your house (I’m not mentioning names) that will want to live his/her life without limitations on the power they use. Count on it.

Otherwise, you can use a transfer switch, such is commonly used with backup generators to run power to essential circuits, leaving the clothes dryer and electric range out of the loop. These switches are cheaper and readily available but may present logistical issues, depending on where your main power panel is.

For a couple of examples, Tom has his whole house switched to the output of his GS8048 inverter pair. One didn’t quite handle it all, but the GS series can be paired for twice the output. With 16kw on tap, he doesn’t have to worry about running anything or everything, saying he has only seen the load go up to 10 kw. If one of GS8048s should fail, he can proceed with care on the other one until the bad one is repaired, but he’s never had a problem with either. He also has a power line connected to the input of his inverters. This is like a giant version of a UPS (Uninterruptible Power Supply) with the switches so set. Change the switches just a bit and the inverter is providing power to the house, with the grid on standby.

During the day, when there is plenty of sunshine, the batteries charge, the a/c cools (his setup has enough reserve power that the a/c starts without a Smart Start), the computers run, the fridge cools, etc. Nothing is going to or from the power company. There is no grid tie meter or agreement with the power company, so make sure the inverter never gets switched to “sell” mode. These modern smart meters will tell on you!

To minimize the load at night, baking and laundry are done during the day. Come night, the modest battery bank gets well into the evening before the inverter decides to switch back to grid to save the battery. The rest of the night, Tom pays his 13 cents for every kwh he uses. Overall, he doesn’t ever buy any of his own power at a markup and he for pay a lot of the bought kwh.

Tom has plenty of solar. By backing off on his nighttime a/c or investing in a bigger battery, he could probably eliminate his grid consumption altogether. He could keep the grid as his virtual backup generator or just give the power company the one-finger wave goodbye.

On my hybrid system, I don’t have the whole house connected and I don’t have one of those fancy interactive inverters. My transfer switch connects my inverter to the circuits you’d want if the grid goes down and a bit more, within the capacity of the inverter. The sun makes the power and I use it to run the freezer, two fridges, home entertainment, computer/internet, microwave, coffee pot etc. And the a/c. And the farm jalopies. There is no grid attached to the solar power system, so consumption has to stay within production. This is mostly determined by how much the a/c is used, as there is much more than enough power for everything else.

I’d use more of the kwh I produce if I had a bigger battery and inverter, but there is no charge for a grid tie connection and no paying out dimes for using my own kwh.

If you are new to solar, consider a hybrid system for both savings and power redundancy. If you are on grid tie and are or will be getting a raw deal, then consider converting to a hybrid system. Sun Electronics should have pretty much everything you need to make the change at a decent price and they back the stuff they sell. –Neal