Solar Panel Efficiency: How Does it Measure Up Over Time?

Most consumers know that an investment in solar power will last 25-30 years. For this reason, the return on investment is important to consider if you are planning to sell your home within a few years of installing solar. Another important consideration is solar panel efficiency. Like any other home improvement, you can expect some minor decline in performance over time.

What is the expected performance of solar panels?

The performance of solar panels is pretty consistent over the decades they are expected to last, however. Solar panel manufacturers and the solar industry in general expect the greatest decline in the first year: approximately 2-3%. After that, a very small degradation rates of half a percent (0.5%) each year may occur.

Warranty information provided by solar manufacturers is helpful information to assess solar panel efficiency. Solar output warranties use an industry standard of 90% output in the 10th year of usage. By the 25th year, solar manufacturers guarantee at least 80% solar panel efficiency.

Warranties and guarantees, of course, are more conservative than the actual performance of solar panels. Manufacturers are using a “worst case scenario” in predicting solar output declines over the years.

Actual solar panel efficiency of the installations on your property could be much higher. Consider the fact that very little (if any) maintenance of solar panels is required. This is because the panels do not include any moving parts, and they have been designed to withstand extreme weather conditions.

This means that an investment in solar power is probably even more sound than you’ll read in warranty information!

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