One of the most common questions we hear from homeowners considering solar installation is: how long do solar panels last? This is crucial because understanding the lifespan of solar panels is essential for calculating the economic viability of the investment. Furthermore, related to the lifespan of solar panels is the issue of how much their efficiency declines over time and how to mitigate negative factors affecting solar panels. All of these will be clarified below.
Efficiency Degradation of Solar Panels
A 2012 study by the U.S. National Renewable Energy Laboratory showed that, on average, solar panel efficiency decreases by 0.8% per year. Although this degradation rate varies depending on the brand of solar panels, premium solar panels have the lowest degradation rate at around 0.3% per year. The efficiency degradation of solar panels has continuously improved with advancements in technology over the years, and a degradation rate below 1% annually is common across the solar panel manufacturing industry. Since this study in 2012, more efficient technologies have been developed, and newer solar panels now only degrade by about 0.5% in energy output each year, which significantly impacts the lifespan of solar panels.
Impact of Efficiency on Solar Panel Lifespan
So how does efficiency degradation exactly affect the lifespan of solar panels? For instance, a 0.8% efficiency decrease means that in the second year, your solar panels will operate at 99.2% of their initial energy output; after 25 years, they will still operate at about 82.5%. A slightly better solar panel with a 0.5% efficiency decrease per year will produce about 87.5% of its initial energy output. To determine the expected output of your solar panels after a certain number of years, you can simply multiply the degradation rate by the number of years you are interested in and subtract that from 100%. Therefore, after 25 years, solar panels will not stop working but will have significantly reduced efficiency (nearly 20% less), prompting manufacturers to recommend replacing them to maintain optimal energy production.
Solar Panel Lifespan
Because of these reasons, solar panels are typically warranted for not exceeding a 20% efficiency loss over 25 years. Sometimes, more important than physical defects covered by manufacturer warranties is the issue of efficiency degradation. Warranty of performance for solar panels can help estimate expected electricity output from a solar power system in the future.
Therefore, in reality, the lifespan of solar panels can range from 25 to 30 years or even longer. However, manufacturers recommend replacing solar panels when their efficiency has decreased by approximately 20% from the original level. With the electricity generated, on average it takes about 5 to 7 years to recover your initial investment in installing a solar power system, and the remaining 20 years can generate profits for you entirely free of charge. This is an investment equation that we can easily see the efficiency in.
The important thing about determining the lifespan of solar panels at this point is understanding what will reduce the efficiency of the solar panel system over time and how to mitigate those factors in the future.
