Here is part of an article by Derek Markham. This was originally posted on Cost of Solar.
When considering going solar, we know that one of the top questions tends to be something along the lines of “How much do solar panels cost?” or “What is the cost of solar?” because for many of us, adding a home solar array isn’t just about reducing pollution and greenhouse gas emissions, but it’s also about the bottom line, which inevitably comes down to discussions of dollars and cents.
Is home solar worth it?Once it’s established that the cost of going solar isn’t nearly as high as people might think, and that a home solar system is well within reach of many homeowners, a popular follow-up question is usually about longevity and reliability, or to phrase it explicitly, “How long do solar panels last?“
Most solar panels used in home solar arrays come with a warranty for some 25 or 30 years, which means that the solar panels are guaranteed for decades, unlike many of the other goods we buy. And again unlike many other consumer goods, they don’t ‘give up the ghost’ at the end of their warranty period and need to be replaced, but continue to still produce clean electricity, although at a slightly less efficiency each year. In fact, some decidedly old-school solar cells have been producing electricity daily for about 40 years or so, and are expected to continue to power homes and businesses for decades more.
According to a study undertaken by the National Renewable Energy Laboratory (NREL) a few years ago, which looked at the ‘photovoltaic degradation’ rates of some 2000 solar installations, the average solar panel loses about half of a percentage point (0.5%) of efficiency per year, which means that a panel at the end of its 25-year warranty period should still be operating at about 88% of its original capacity. However, not every panel will see degradation rates as high as 0.5%, as shown by this 30+ year old solar panel, which outperforms its original specs, even after decades in the sun.
This decades-long life of solar panels makes the economics of going solar even better, as most systems will pay for themselves within the first ten years, and yet still produce many many more years of clean electricity for their owners, so asking “How long do solar panels last?” might be the wrong question.