Do Solar Panels Lose Efficiency Over Time?

By Geoffrey Sperring

March 18, 2025

You've had your solar installation for several years, and things have been going quite well. The savings you've had with solar power have provided a full return on your initial investment — and then some! Perhaps you're able to generate all of your electrical needs with the sun alone. It's only reasonable to wonder when all this good is going to come to an end.

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While it's true solar panels deteriorate, the losses should be relatively small. These losses include light- and potential-induced degradation, age-related degradation and weathering.

Do Solar Panels Lose Efficiency With Age, and How Does This Happen?

Solar panels are exposed to all kinds of weather. They must withstand intense heat from the sun, extreme weather, rain, snow and ice as well as dust, dirt and weathering. Some of the mechanisms that affect solar panels include:

Light-induced Degradation

When panels are first exposed to the sun, the sun's energy causes tiny atomic changes in the cells, effectively reducing the cells' conductivity. This continues for the first 1,000 hours of exposure before stopping. Measurements by the National Renewable Energy Laboratory show this one-off loss is between 0.4% and 0.9%.

Potential-induced Degradation

PID mainly affects high-voltage solar panel strings operating at voltages higher than 500 volts DC. It's caused by leakage currents between the cells that reduce solar panel performance over time. Effective grounding (earthing) and improved water sealing reduce PID.

Age-related Degradation

This is caused by a gradual deterioration of the electrical components inside the PV cells. Age-related degradation causes a loss of solar panel output of 0.5% per year on average.

How Long Is the Lifespan of Solar Panels?

Solar panels degrade slowly. The NREL measurements above showed that the yearly change in performance based on a selection of solar cells over 5 years was between 0.1% and 1.1%, with an average of 0.53%. Based on this average, the solar output after 20 years would fall by 10.5%. It will be less for top-quality panels and more for cheaper units.

Some of the factors that affect the rate at which solar panels lose efficiency include:

Panel Quality

Superior quality solar panels made from top-rate materials last longer and maintain performance better than cheaper panels with low-quality glass, inferior cells and flimsy frames.

Installation

Proper handling is a crucial factor during storage and installation. Careless handling may cause microcracks that let in moisture and cause internal damage. It's also crucial to choose good quality weatherproof solar panel connectors.

Maintenance

Regular solar maintenance extends the life of your PV system. Remove dust and leaf debris periodically using a hose and panel brush. Periodically check the integrity of the electrical connections between the panels for corrosion and wear. Depending on the slope of the roof, it may be better to use professionals.

Weather

After heavy storms, carefully inspect solar panels for damage or cracked glass. These must be replaced as they aren't repairable. Solar panels are usually connected in series, and one faulty panel severely restricts the output of the whole solar array.

What Are the Effects of Solar Panel Degradation?

Do solar panels lose efficiency with age? The answer to this question is yes. While they deteriorate slowly, a point eventually comes when the output of the solar array may be insufficient for the load. If you're using the inverter to produce electricity into the grid, you may notice that utility credits are lower than they previously were.

The main points arising from solar panel aging include:

A limited lifetime. Budget solar panels have a limited lifetime, while premium panels may last longer than 30 years.
Solar power decline. Solar power will gradually reduce. There will be a time when the energy output loss means you may need to replace or upgrade the installation.
They continue to work. Although solar panel output declines, aging solar panels can continue to work almost indefinitely, provided you maintain them properly.

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Preventing Solar Panel Degradation Over Time

The complete solar installation, including inverters, batteries and mains connection, is a one-time major investment. If you make the right choices, solar panel degradation rates should be low, and they'd only need replacing after 25 to 30 years. Points to consider include choosing the right panels, a long-term warranty and professional installation.

Choose the Right Type of Solar Panels

There are three main types of solar cells:

Monocrystalline. These are the best types with the highest efficiency. They have the longest panel lifespan and excellent efficiency.
Polycrystalline. This type of panel is slightly cheaper and not quite as efficient. While not as long-lasting, polycrystalline panels are suitable for at least 25 years.
Thin film. Thin film is a flexible choice that's suitable for almost any surface. While cheaper, these panels degrade faster and are relatively inefficient.

Professional Installation

You'll reduce the risk of premature solar degradation by working with a professional. A solar installation is complex, and installers must comply with local and NEC regulations. The DC voltage from solar panels is potentially dangerous, so safety precautions are essential.

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