Most performance warranties guarantee a solar panel life expectancy that the panel will produce at 80 percent or greater of rated capacity for the term.
Someone told me I need to replace my 20-year-old solar panels because they’re no longer efficient. Is this true?
Gary T.
Solar Panel Life Expectancy
Like my Grandpa used to say, “If it ain’t broke, don’t fix it!” Every solar panel has its own production profile depending on the type of solar panel you have (monocrystalline, aka “mono”; polycrystalline, aka “poly”; and thin-film are three main forms). Locate your specific solar panel on the manufacturer’s website under “product support,” and download the warranty provisions if they’re still available. Then, find the clause for the performance or power limited warranty. (Don’t confuse the performance warranty with the product defect warranty, which typically guarantees the equipment for 10 to 12 years.) Most companies offer solar panels with a performance warranty of 25 or 30 years. Mono and poly panels will lose a significant amount of performance the first year (known as the “burn-in period”), then gradually taper off indefinitely. Most thin-film modules won’t experience a significant first-year performance drop, but they’ve historically been lower-wattage modules with much lower cell efficiencies.
The warranty will tell you how well your panels should be performing at the end of the specified period. For most of the solar panels I’ve seen, the performance warranty guarantees the panel will produce at 80 percent or greater of rated capacity for the term. I’ve heard of solar panels still producing at usable levels for 50 years or more. The problem is that large-scale manufacturing of solar panels is a fairly recent activity, so there isn’t enough operating history for us to have observed exactly how long they’ll last. Many solar manufacturers have closed their doors, and their panel warranties aren’t worth the paper they’re printed on.
Your solar panels are more likely to fail from moisture getting into the solar cell layer because of hail cracks and bad seals than from the panels wearing out. So, keep your panels until they quit working or you have a warranty claim. You may have trouble finding comparables to replace older panels. In the meantime, if you want more power, add another solar array to complement the one you already have.
Farewell, Kerena!
With great sadness, we say farewell to Kerena Reese, who’s been a valuable member of my company team since her graduation from Texas A&M University. She’s contributed to the design and project management of solar and energy-storage projects and, more recently, to this “Gone Off-Grid” column. Kerena now lives in a rural Oklahoma community, where she cares for animals at a local animal rescue shelter and is fixing up an older home.
May all your days be filled with sunshine – even when it rains!
Send Us Your Power-Full Questions
We’ll do our best to answer your questions on energy subjects in upcoming issues. Email them to Letters@MotherEarthNews.com with “Energy Q&A” in the subject line.
May all your days be filled with sunshine — even when it rains!
Hoss Boyd is founder, president, and CEO of TeraVolt Energy. Kerena Reese is an independent engineer. They’re recognized solar and energy-storage experts.
