Science

The Solar Burn, Part 6: Choosing a System That Won’t Burn You

This is Part 6 of a multi-part series about my attempt to install solar panels on my house. For the previous installation, CLICK THIS LINK. For the next installation, CLICK THIS LINK. To start at the beginning, CLICK THIS LINK. Thanks for reading!

Choosing a System That Won’t Burn You

There are many things under the Sun, and that includes the wide variety of solar arrays that you can install. I won’t try to describe them all, because I try to keep the length of my posts under a million words. So I’ll just give you a sampler of what seem to be the most common varieties.

The classic system is the one we see most often, where solar panels are installed on the pitched roofs of houses. If you’re going to go this route, there are several matters to worry and fret about. One is the direction your panels will face.

If you want to generate the most electricity possible from your panels, the obvious best direction is due south, because that’s where the Sun reaches its highest point, each and every day. But even though that’s the best direction for generating juice, it may not be best for saving money on your electric bill.

We humans tend to use the most electricity in the late-afternoon and early evening hours. That’s when we get home from work, turn on the AC if it’s a hot summer day, fire up the electric range to cook our dinner, and then run a load of laundry. Because of this, demand for electricity skyrockets during these hours. And due to the law of supply and demand, the electric company tends to charge a premium for electricity at this time of day.

During the afternoon, you’ll generate more premium-priced electricity from your solar panels if they’re aimed southwest, rather than due south. Because that’s where the Sun is, in the afternoon. So if the roof of your house faces southwest, be happy. If it doesn’t, try standing on a ladder, grabbing your roof, and rotating it. If that doesn’t work, you might want to build a new house.

Standard advice on the tilt of your panels is that it’s best that the tilt matches the latitude where you live. Because that’s perpendicular to the average angle of the Sun, throughout the year. Thus, if you live at 40-degrees North latitude, it’s best that your panels be tilted at 40 degrees. This means your roof should be pitched at 40 degrees. I can give you some ladder advice on correcting your roof pitch, but you might just want to build a new house.

Actually, NASA researchers have discovered that you’ll get a little more juice from your solar panels if your roof pitch is about 5 degrees less than the latitude you live. Why this is, I don’t know, but I wouldn’t sweat it much. When I’ve crunched various panel tilts using the government’s online PVWatts Calculator, I’ve found that tilt doesn’t make a huge difference in the energy output of solar panels, as long as your panels are basically tilted toward the sun, or are at least lying flat.

NASA has conducted considerable research on solar energy, and topics like optimal tilt of solar panels.

And if you have a flat roof, there’s good and bad news. You can have panels installed on ballast racks. This type of rack doesn’t have to be bolted onto your roof. Rather, it can be weighed down by heavy, concrete blocks. The bad news is that if you don’t have a strong enough substructure in your roof, it will begin to sag under the weight, after a few years. Then, pooling of rain water may occur, which can lead to roof leaks.

If you own a lot of acreage, you can install a ground-mounted system, then run a trench to your house for the electric line. That makes for easier installation and maintenance, and protects your roof from having holes drilled into it. Plus, you have more control over the direction you aim your panels.

You can also install your panels on a pole, that moves with the Sun throughout the day, thus maximizing the output of your panels. But these systems can be expensive to install and maintain. They may only be economical if you can install the pole array where it’s free from any shade, throughout the day.

Probably your most important choice for solar equipment is the inverter, and not the solar panel. There are many brands of inverters, but the two major brands are Enphase and SolarEdge. Together, they make up nearly 90% of U.S. market share. Whoever you choose as your solar installer will probably use one or the other, or give you a choice of either.

An Enphase system uses microinverters, installed on the backs of each solar panel. This allows you to add an unlimited amount of solar panels in the future, without a problem. But SolarEdge uses a string inverter, which limits the amount of panels you can add in the future.

Enphase offers a new “Sunlight Backup” system that allows you to use your solar panels during blackouts, without having to have a battery storage system. However, it’s so expensive you might be better off just having batteries.

Enphase batteries are criticized for being a lot more expensive, while storing a lot less electricity, than other brands of batteries. SolarEdge batteries, on the other hand, are touted as the best and most economical on the market.

Enphase microinverters are notorious for overheating. And when they overheat, they produce a lot less electricity. Because of this, SolarEdge, with its power optimizers and string inverter, is regarded as being more efficient than Enphase.

But Enphase microinverters have a 25-year warranty. Which you may need, because they’ve had reliability issues in the past. The SolarEdge string inverter has a 12-year warranty. But its power optimizers, attached to each solar panel, have a 25-year warranty. But SolarEdge has also had reliability issues. So hang onto your warranty information, regardless of which system you choose.

The top three solar panel manufactures, in terms of quality, are SunPower, Panasonic, and LG. However, LG recently stopped making solar panels. Apparently, they’ve experienced The Solar Burn. That leaves us with SunPower and Panasonic. Panasonic also recently stopped making solar panels. At least, in Panasonic factories. Now they’re outsourcing their production to third-party factories.

Assuming the quality of Panasonic panels doesn’t go all to hell, due to the outsourcing, then this brand of panels is probably your best choice. Especially if you don’t want Enphase microinverters. Enphase and SunPower enjoy a close business relationship. So if you want SunPower panels, your solar installer may be obligated to use Enphase microinverters.

SunPower’s solar panels are the most efficient on the market, and currently rate a 22.8% efficiency. However, Panasonic comes close, with its new EverVolt panels, at 21.7% efficiency. The industry standard is 17%. But Panasonic panels tend to handle heat better than SunPower, so they might be your better choice if you live in a hot climate.

All solar panels degrade over time, generating less and less electricity, the older they get. But apparently SunPower and Panasonic panels degrade very slowly. SunPower claims its panels will maintain 92% of their original efficiency after 25 years. Panasonic’s claim is 90.76% after 25 years. But who knows? These are newly developed panels. Only time will tell, and I’ll probably be dead in 25 years. I’ll have to reincarnate in order to make any claim on their 25-year warranties.

These are some of the types of solar array systems available. Next we’ll discuss how to avoid The Solar Burn, while dealing with the devils who sell solar array systems.

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25 replies »

  1. I actually designed a 3-phase inverter for my second semester senior project at college. My first version fried every transistor because I made a mistake powering it up. But my second version worked thankfully and I passed the class.

    Liked by 3 people

  2. My brain may be swimming after reading all of this, but thanks for the information. I will let Brad digest it and I will go shopping, since I am sooo “high maintence.” according to a certain doolally.

    Liked by 1 person

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