Solar Panel Aging According to Manufacturer Claims — Is It Accurate?

Measuring Solar Panel Degradation

Solar panel degradation is usually measured by comparing the initial power output to the power output after a certain number of years. The industry standard for measuring degradation is to calculate the capacity retention, which is the percentage of the initial power output that is still produced after a certain period. For example, a panel with a 20-year warranty might claim a capacity retention of 80% after 10 years. However, real-world data suggests that actual capacity retention can be significantly lower, often in the range of 70% to 80% after 10 years.

Factors Influencing Solar Panel Degradation

Several factors can influence solar panel degradation, including temperature, humidity, and exposure to UV radiation. High temperatures can accelerate degradation, while high humidity can lead to corrosion and further reduce performance. Panels installed in coastal areas may experience more rapid degradation due to exposure to salt and pollutants. To mitigate these effects, installers can take steps to ensure panels are properly cleaned and maintained, and consider using panels with higher temperature coefficients to minimize the impact of heat.

Real-World Data vs. Manufacturer Claims

Real-world data from various studies and monitoring programs has consistently shown that solar panel degradation exceeds manufacturer claims. For example, a study by the National Renewable Energy Laboratory (NREL) found that commercial solar panels degraded at an average rate of 0.3-0.5% per year, while manufacturer claims suggested a degradation rate of 0.2-0.3% per year. Similarly, a study by the University of California, Berkeley found that solar panels installed in California degraded at an average rate of 0.4-0.6% per year, exceeding manufacturer claims by 10-20%. These findings highlight the importance of considering real-world data when evaluating the performance and lifespan of solar panels.