Do Solar Panels Lose Efficiency Over Time?

Solar panels are a long-term investment, but like any working capital, they lose efficiency over time. Find out how to account for any drop before you buy.

Today’s solar panels are built to last for decades, but that doesn’t mean they’ll work at peak efficiency decades from now.

With the harsh Las Vegas climate added to the mix, you may wonder if solar panels lose efficiency over time. A rooftop solar panel installation is an investment, and any significant drop in efficiency can threaten its viability. The good news is that losses in efficiency in today’s solar panels are small, predictable, and still leave homeowners in the green.

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Why Do Solar Panels Lose Efficiency Over Time?

The pace at which solar panels lose efficiency over time is called the degradation rate and is a natural consequence of their exposure to the elements. According to a 2012 study by the National Renewable Energy Laboratory, panels lose anywhere from 0.5 percent to 0.8 percent of their production capacity each year. This is unavoidable, but it occurs slowly enough that it is a negligible factor for the vast majority of homeowners. There are two other ways that solar panels can lose efficiency, thanks in part to their chemistry acting against them.

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Light-Induced Degradation

Just as a new car loses some of its value the moment you drive it off the lot, a solar panel can take an efficiency hit within hours of its first use. Known as Light-Induced Degradation (LID), this occurs when the boron coating of the solar panels oxidizes and partially clouds the panels. This obstruction can sap anywhere from 1 to 3 percent of a solar panel’s efficiency within hours of its first exposure to sunlight, but does not progress beyond this point.

Potential-Induced Degradation

A newer phenomenon called Potential-Induced Degradation (PID) may also impact solar panels over time. While the full mechanics are still yet to be understood, electrical leakages from the solar panel, due to high humidity and sodium build-up, can arc back and damage it. The good news is that this condition is rare in the United States and is mitigated by the way electrical systems are designed here. However, it is still possible, which is why working with an experienced solar installer is important to mitigate your system’s risk of it.

What is the Lifespan of Solar Panels?

Given how new solar panels and their widespread adoption are, there isn’t much information about their full lifespan. However, many older solar panels continue to function, meaning if you’re planning on having yours for the long haul, you could have years of clean energy ahead of you. Most manufacturers offer a 25-year guarantee on their panels, which is the standard metric used to measure their expected lifespan. Many manufacturers stipulate that their panels will still produce at least 80 percent of their original energy capacity by this time.

Do solar panels lose efficiency over time? The answer is yes, but the process is slow, and in the vast majority of cases, the effect is small, easy to calculate, and won’t affect a homeowner’s decision to install a system. The Department of Energy estimates that for rooftop systems utilizing current multicrystalline-silicon PV modules, the estimated payback time in energy savings is as little as four years. Beyond that point, rooftop solar systems can still produce energy at near-peak levels for years. Today’s solar panels are more efficient and resilient than ever, making it a great time to invest in solar for your home.

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