Latest articles by The Solar Nerd

Installing solar panels on your house is a pretty big investment - one that you’d like to last as long as possible. So how long should you expect your home solar array to last? Solar panels last a really long time. You can expect at least a 25 year lifespan. Premature failures do happen, but they are often covered by the manufacturer’s warranty. Solar panels have been known to last much longer - as long as four decades - but there is little data because mass commercialization of photovoltaic panels really only started happening in the 1970s.

If you pay a solar contractor to install solar panels on your home, most of the nitty gritty technical terms are hidden away from you. They will give you an easy to understand proposal, and then one day you have shiny panels on your roof, generating electrons. It’s nice! But if you’re undertaking a DIY project, all the calculations are up to you. One concept that you may come across is the solar panel derate or derating factor.

The residential solar industry in the US is dominated by a few very large companies, and one of the biggest is Momentum Solar. According to Solar Power World, Momentum installed almost 90 megawatts of solar panels last year. For perspective, the average home solar system is 6.4 kW in size. If Momentum installed only average sized systems, their installations in 2019 would be equivalent to 14,000 home systems. That’s a lot!

Solar panel manufacturers are always competing against each other to squeeze the most power out of the same size solar panels. If you installed solar panels on your home 10 years ago, you probably had panels with efficiency in the mid-to-high teens (by percentage of light converted to electricity). Today, you can commonly find solar panels that convert more than 20% of the incoming light into electricity, with the current best residential panels hitting nearly 23% efficiency.

The average size of a home solar installation in the United States is around 6 kilowatts, which is about 17 high efficiency premium solar panels, or more if you go with a cheaper panel. That many solar panels takes up a lot of space, and you would need a large available roof area to accommodate them. But sometimes, your roof might not be ideal for solar. It might be oriented east-west (which generates less power than a north-south orientation) or, more commonly, you might have shading from nearby trees or buildings.

If you like to get off the grid, whether it’s roughing it in a tent, or you’re more of a “glamper” who likes to stay comfortable in a boat or RV, you probably still like to have electricity to keep your devices powered. We’ve written articles about some of the solar technology you can use to make this happen, such as flexible solar panels, charge controllers, and solar phone chargers. However, if you have big power requirements that involve keeping a larger battery charged, things get a little more complicated.

Are you a meticulous number cruncher who breaks out the spreadsheet whenever you’re planning a big product purchase? I certainly am. The last time I bought a car, and made a spreadsheet with the specifications of all the car models I was considering. I rank-ordered them in each of the categories that were important to me, and made my decision based on which one performed the best. Figuring out which solar panel is best for you is a little like that, although with this article I hope to make is less complicated for you.

Solar panels don’t have any moving parts. They just quietly sit on your roof or in your backyard for a couple decades and generate electricity, day in and day out. How cool is that? A study by the National Renewable Energy Laboratory shows that new solar panels have a failure rate of only 5 in 10,000 per year. This means that every year, a solar panel has a 0.05% chance of failing, or a total 1.

At one point, Sungevity was the 5th largest residential solar installer in the United States. In 2017 it died (Chapter 11 bankruptcy), sold its assets, was reborn as a new company called Solar Spectrum, merged with another California installer called Horizon Solar Power, and then it brought back the Sungevity name. Along the way, it used debt and private equity to pursue a strategy of high growth - presumably to keep up with other high growth rivals like Sunrun and Vivint.

Homeowners who are interested in going solar often want to know how many solar panels it will take to power their house. The most accurate way to find that out is to get a professional solar installer to perform an analysis on your home. A quick but somewhat less accurate way is to read your monthly electric bill and use our solar calculator to determine what your power generation and estimated system price would be.