Solar panels lose between 0.5% to 1% of their efficiency every year. Because of that rate of loss, at the end of the 25 year warranty period, the panels will still output between 75 to 87.5% of the original amount of power they made when they were new. In fact, a National Renewable Energy Laboratories (NREL) study found that 80% of all solar panels outlast their 25 year warranty period. That same NREL study also shows that 78% of the systems tested in the study showed less than a 1% degradation rate per year. You may ask, “Are solar panels that still put out 75% or more of their original output still useful?” Yes! If your panels are still putting out most of the energy they were originally designed to produce, those panels are still useful.
If your panels last longer than they are warrantied for, that boosts your ROI(Return On Investment). Online calculators often use the common 25 year warranty period that solar panels come with as the basis for how long your system will last, and therefore, as a basis for how long you will own it and earn ROI. However, if your panels last for longer than 25 years, all that extra time means extra time that you are earning ROI on your investment in solar. The best way to make sure you get maximum ROI on your system is to properly maintain the system. Thankfully, there’s not much you need to do.
All you need to do to maintain maximum output from your solar system is to occasionally dust off the panels. You should also keep trees trimmed and clear of your system so the shade doesn’t reduce your systems’ power output. Solar panels are very reliable and they don’t need any maintenance beyond keeping them clean.Inverters are another story. They are often warrantied for 10 years.
Demand Solar only uses products with 25 year warranties.
Reference: Dirk Jordan and Sarah Kurz. (2019) Photovoltaic Degradation Rates — An Analytical Review National Renewable Energy Labs.
Web 22 Apr 2019