Solar Panel Degradation Explained

Solar panels slowly produce less electricity as they age, a process called degradation. EnergySage reports a median performance loss of about 0.75 percent per year, citing a 2024 national laboratory study. This guide explains what that rate means over the life of a system and why some panels hold up better than others.

The Annual Degradation Rate

Degradation measures how much production a panel loses year over year. EnergySage reports that solar panels experience a median performance loss of about 0.75 percent annually, citing a 2024 national laboratory study.

That pace compounds slowly. EnergySage states that after 25 years, panels typically operate at roughly 81 percent of their original capacity, so a system keeps generating the large majority of its rated output well into its later years.

How Long Panels Last

Degradation does not mean a hard stop at a set date. EnergySage states that solar panels typically function effectively for 25 to 30 years, and that some premium models may last up to 40 years.

After that window the panels still generate electricity, just at a reduced capacity that eventually makes replacement sensible. EnergySage notes that most panels remain functional well beyond their warranty periods, so the end of a warranty is not the end of useful production.

Climate and Panel Quality

The degradation rate is not fixed across every panel or location. EnergySage reports that degradation varies by climate, with cooler regions showing roughly 0.48 percent annual loss and hotter zones experiencing about 0.88 percent.

Manufacturer quality also matters. EnergySage notes that premium makers such as Maxeon offer rates as low as 0.25 percent per year. Lower degradation means a panel holds more of its output over time, which is one reason warranties and degradation specs are worth comparing between products.