A solar panels' lifespan depends on factors like climate, the materials used in the panel, and how well it's installed. .

On average, well-built solar panels last between 20 and 30 years before their power output begins to decline significantly. Several factors affect the longevity of solar panels, including the type of materials used, the quality of manufacturing and installation of the solar panel, and the climate where they operate.1

Older models of solar panels tend to degrade more quickly than newer models and are generally less reliable than those installed after the year 2000. Residential solar panels will often come with a 25-year warranty, after which they are not guaranteed to produce the same amount of electricity as they did when first installed.2 

Solar Panel Degradation

As solar panels age, they begin to degrade; although they may no longer be considered functional, they still produce electricity to some degree. Degradation is a measure of the decrease in output of a solar panel over time. This is not the same as failure, which happens when the solar panel suddenly stops producing electricity. Solar panels may degrade to the point where they fail, or they may just continue degrading, gradually decreasing their electrical output until it is no longer economically feasible to operate them.

Research by the National Renewable Energy Laboratory has shown that the median yearly degradation rate of solar panels is around 0.5%. If a solar panel has been operational for 10 years, its electricity output will have dropped to around 95% of its original production level. The process of degradation in the hydrogenated amorphous silicon used in many solar panels is known as the Staebler Wronski effect.3 As the material is exposed to light, its ability to conduct electricity decreases. 

Degradation can also occur because of higher temperatures. Solar panels mounted directly on rooftops typically reach higher temperatures than those installed on the ground.4 Systems in hotter climates also tend to have lower efficiencies than those in more moderate climates. Another cause of degradation includes discoloration of the EVA, or plastic encapsulate, which can interfere with the amount of sunlight the solar cells receive. Delamination can occur when the EVA breaks apart from the glass covering of the solar panel. This can cause degradation because it allows air, dust, moisture, and other harmful contaminants to enter the panel.5 Other physical failures and damages to the solar panel can also cause the electrical output to decrease. 

How to Improve Solar Panel Efficiency

• Have your solar panel installed by a professional.
• Pay attention to the orientation and tilt of solar panels to ensure maximum sun exposure.
• Make sure the solar panels are not shaded by trees or other obstructions.
• Use cooling systems to decrease temperature so energy output increases.
• Reduce the amount of light reflection by using an anti-reflective coating.

How Long Do Solar Batteries Last?

Solar batteries can last anywhere from three to five years on average.6 Lithium-ion, lead-acid, and nickel batteries are some of the most commonly used types of batteries in solar energy systems.

Just like solar panels, solar batteries degrade over time. Their ability to store energy decreases because of factors like how much load the battery is connected to, how efficiently the batteries charge and discharge, and temperature. By operating solar batteries at optimal temperatures and using a battery management system to make sure it doesn’t overcharge or fully discharge, the lifespan of solar batteries can be extended.  

What Happens to Solar Panels After Their Useful Life?

Damaged solar photovoltaic panel.

Once a solar panel has come to the end of its useful life, it must be decommissioned. In panels made from silicon, glass, aluminum, and copper may be recycled.

While it is possible to reuse or recycle parts of a solar panel, only the European Union has regulations requiring the recycling of these materials. Japan tests solar panels for hazardous waste before disposal and may suggest specific ways to recycle or dispose of the materials.

In the United States, solar panels are handled as hazardous waste and fall under the regulations of the Resource Conservation and Recovery Act. States like California are in the process of developing regulations for recycling parts of solar panels that are at the end of their useful life.

However, not all parts of solar panels can be recycled, and these components are disposed of in a landfill. Reusing or recycling solar panel materials presents a huge opportunity for countries to recover money and resources.