How long do solar panels last?

If you install solar panels on your home, how long should you expect them to last?

Photo of a solar array

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?

Conventional silicon solar panels that are designed for a rooftop or utility installation can be expected to last 25 years. Some of the top brands come with 25 year product warranties, in which case you can consider 25 years to be the minimum lifespan. This is backed by accelerated testing done by independent labs. Solar panels have been known to last even longer - as long as four decades - but there is little data because mass commercialization of photovoltaic panels really only started happening in the 1970s.

There are other types of solar panels too, but they may not be designed to be as durable. For example, you can get flexible solar panels that you can glue or velcro to the roof of a camper or boat to provide lightweight off-grid power. These aren’t designed to withstand hurricanes and hail like rooftop panels are, and sometimes come with only a 1 or 2 year warranty. You might expect solar panels that are designed for portable use to last only a few years.

This article will focus on the longevity of solar panels that you might install on your home.

What is the expected failure rate for solar panels?

According to research by the National Renewable Energy Laboratory, solar panels manufactured after 2000 have a failure rate of about 5 panels in 10,000, or a 0.05% failure rate per year. That means one solar panel has about a 1.25% chance of failing before it gets to be 25 years old. This means the vast majority of solar panels should work for 25 years or more.

What’s the chance that you’ll ever have a solar panel failure in your home system?

A 1.25% failure rate in 25 years is still really small, but remember that you’ll have many solar panels in your home array. Arrays differ in size, but 20 panels (about 6 kW) is about average. This means that, in a 20 panel system, you would have about a 31.25% of ever experiencing a solar panel failure during the expected 25 year lifespan of your array.

Is that something to worry about? Not necessarily, especially if you have microinverters, because the failure of one panel won’t affect other panels in your array. If the failure happens toward the end of your system’s expected lifespan, you could simply ignore the failed panel. You’ll generate a little less electricity, but you’ll avoid the expense of a service call and replacement - that is, unless you have a warranty that covers labor.

What are the best solar panel warranties?

Any panel you buy will have a 25 year power warranty, but only a few have 25 year product warranties that cover any failure, and even fewer include labor in the warranty coverage.

We think that SunPower has the best warranty in the business, but four other manufacturers also offer 25 year product warranties. You can read about them here.

What is solar panel degradation?

Even if your solar panel is still operating 40 years from now, it won’t be working as well as it was when brand new. Silicon photovoltaic panels degrade over time, which causes them to generate a little less electricity every year.

This degradation is covered in the 25 power warranty. Read the fine print of your warranty closely, and you’ll see how much that degradation is expected to be. The cheapest panels have an 80% 25 year power warranty. This means, after 25 years, the panel may generate only 80% as much electricity as when it was new.

That’s still pretty good, considering that the panel has been sitting in the sun, rain, wind, and maybe even snow and ice for more than two decades. But the best power warranties have a 90% or better guarantee. These include premium manufacturers such as LG, Panasonic, and SunPower.

Tips and further reading

We also wrote an indepth article about the different ways that solar panels can fail, and the testing standards that are part of the industry.

Solar panel reliability is different from warranty length. Just because a manufacturer offers a really good warranty, that doesn’t mean their product will necessarily last the longest. Third-party testing shows that some cheaper brands can actually outperform the premium manufacturers.

#Reliability #Longevity

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