Kris Kristofferson had a big hit with a song on that theme. Instead of moaning about why things had gone so wrong, though, he was wondering why good things had happened when he felt he didn’t deserve them.
Well, things can go wrong in your solar power system, just like anything else, and you’ll have to get off your wallet to fix them. You can ask, “Why me?”, but if you are just feeling sorry for yourself it’ll likely happen again. If you ask “Why me?” constructively, that is to say, analyze what you might have done differently, you might end up with a better and stronger system that won’t have such a failure in the future.
Here at the Solar Shed, I have all kinds of experiments running. Many are temporary, but sometimes stick around longer than expected. If I get sloppy on these temporary rigs, then it can get expensive. Also, different circumstances seem to offer different “learning experiences”.
Example 1–Do you know what the schematic symbol is for an antenna? Visualize an upside down wire coat hanger and you have a pretty good idea. If you have 3 solar modules in series, you can twist all the wires together and have the pair for the downline together or you can have them take the shortest path, with ends up with a more or less triangular circuit…just like the antenna symbol. Now, a loop antenna is directional, so if lightning hits the tree over yonder, the induced current from the blast may be out of phase and not bother your system a bit. OR it may be 90 degrees around and channel the hit right into your system, which can get expensive. Trust me, I know this to be true. Keep your wiring tight and not looped.
Example 2–If you do not have a surge arrestor on your system, you should not complain about a surge getting in and causing havoc. In the spring time, we have some really nasty lightning storms around here. I mean, go hide under-the-bed-with-the-cat-bad storms. In a case of Example One and Example Two combined, you may discover interesting things. For one, a charge controller might NOT be injured by lightning, but because it operates slowly it can pass it along to your inverter. The inverter monitors its output and adjusts according to the input with which it has to work, but this adjustment is not lightning fast, so you can get some really interesting effects. One brand of inverter I had online would blow its display board. It was the weakest link and it took the hit, saving everything else. It would run just fine without the board, but I had spares. After a couple of times of this, I was out of spares and decided to run without display. I had other meters. I did, however, lash up an output surge arrestor. Good thing. The next storm did not kill the inverter, but it wiped out the feedback loop, so it got the urge to keep making lots of voltage…lots more than is considered socially acceptable. Fortunately, I had put in that output surge arrestor and only it went up in smoke. Otherwise, everything in the house on that circuit would have been destroyed. The saddest part of the story is that my new 48v system, not yet online, lost its big 12kw inverter. Have you priced a 12kw inverter? They cost a lot more than surge arrestors! I think the system packages that Sun Electronics sells pretty much have arrestors in the kit, but ask. If building a system a la carte, install surge arrestors!
Example 3–Nothing bad happened, here, because I was prepared. Lots of gear has fans in it. All of my charge controllers have them and the Sun King 5548 inverter that I built in the shell of my deceased 12kw inverter recently had one of its fans start getting noisy. There is a manual fan in the top of the case that I use a lot in hot weather and another fan operated by a thermostat on the transformer. That one never runs as I am running 5500 watts on a 12,000 watt transformer. Right down on the driver board, there is a small fan that runs based on the heatsink temperature. This one is pretty important and it would rumble and howl when it started up. In this inverter’s design, heat won’t cause it to blow up, but it will shut down until it is comfy again. Having the lights and a/c blinking on and off on a warm day is really annoying. Folks, when your fans start talking you need to listen. I have a drawer full of fans for just such occasions. I bought two extra when I built the inverter and I have several more dissected from old PC power supplies by an 11 year old who likes to take things apart. Never throw away working fans! If you buy replacement fans, TRY to get ball bearing fans. They cost more than fans with sleeve bushings, but they last WAY longer. The specs, like voltage, current and airflow (CFM) are usually printed on the hub of the old fan. Listen to your fans. They mean it!
Example 4— Pay attention to the meters. I recently pulled a set of 2 year old batteries from the system. Why me? I have batteries 5 years old that are just fine! Interestingly, it wasn’t just one battery with a bad cell. I was hoping to use some of that set in other 12 and 24v systems around the farm, but No-o-o-o-o, they were all bad. Curious. Well, it seems I had two charge controllers that had a bad firmware revision and may have had some damage from all those lightning episodes. Since they run less than half the power for the whole system and otherwise seem well-behaved, I ignored the high-ish afternoon voltages, thinking they were supposed to go that high as part of their multistage charging act. Nope, they were cooking the batteries. Pay attention to the meters. They are there to tell you stuff!
Example 5–Unless you have sealed batteries or some of those fancy Lithium packs, then there’s a good chance you will need to add water to your batteries from time to time. How often depends on how hard and how deep they are cycled. If you pretty much use up the battery at night and have enough solar to charge it hard, you will probably go through a good bit of water. Once a month is probably good for most folks, but that previously mentioned set that died young was going through gallons every two weeks. Keep the water above the plates and use only distilled water. It is only a buck at the grocery store or WalMart.
Example 6–Keep your terminals tight and clean. Terminals just get loose and need to be tightened. Otherwise, they can run hot and waste power or even burn off the lugs of your battery or inverter. Just today, I opened the cover of a charge controller to get to the temperature sensor wire and while I was in there I decided to check the terminals. Two were not loose enough to cause harm, yet, but needed to be snugged up, just the same. On your batteries, you can add the threat of acid corrosion. Don’t let that green stuff build up. Clean it up and coat with grease for protection.
Example 7–Pay attention to the heat. I haven’t had any problem from this, but it got uncomfortable in the Solar Shed’s control room/man cave last summer. There was no ceiling, then, and the backside of a solar panel is hot. The IR thermometer showed 140-150 degrees and the room was routinely over 110, even with the door left open. This had its own issues, like random animals showing up on the couch. The a/c I had didn’t even stand a chance. There is now a ceiling and insulation, so much of that issue is handled. I will be adding a vent fan and, budget permitting, a mini-split heat pump. Mostly the heat pump will be for me. A check of the spec sheets on all the gear indicated we were well under the too-hot mark. If you don’t have temp specs, you can check the equipment itself. Lick a finger and touch it to a transistor. If it doesn’t sizzle, you are good. If it sizzles, you are close to the limit. If you don’t get back all of the finger, then it is too hot and you need to cool things down.