How long do solar panels last?

The lifespan of solar panels

The industry average solar panel lasts 25-30 years. This lifespan varies by the type of solar panel, brand, and the environment they are installed in. 

We are living in the golden age of solar panels. The adoption of solar panels has grown significantly in the past 10 years and shows no signs of slowing. Thanks in part to renewable energy incentive programs, improvements in technology, and overall decreasing cost of installation. 

In fact, the EIA found in a recent study that in 2020 the total shipments of solar panels increased 33%. 

Do solar panels get less efficient over time?

Over time solar panels become less efficient. Meaning they produce less electricity from the same amount of light. This process is called degradation. A study from the National Renewable Energy Laboratory found that panels lose anywhere from 0.5 percent to 0.8 percent of their production capacity annually. The rate at which solar panels lose efficiency is called the degradation rate. 

Higher-end solar panels will have lower degradation rates. This allows them to produce more electricity over their lifetime, thus reducing their payback period.

Most quality solar panels have a 25-year warranty that guarantees that the panel will maintain at least 80% of its original efficiency over its lifetime. 

Solar panel efficiency chart:

What causes solar panels to become less efficient?

All solar panels will become less efficient over time thanks to four main contributing factors:

• UV Exposure
• Thermal cycling
• Damp heat
• Humidity freeze

UV exposure

Solar panels are exposed to a large amount of ultraviolet (UV) light. Over time the UV rays cause discoloration of the backside of the panel that protects the photovoltaic cells and electrical components that are actually doing the work of converting the sun’s rays into electricity. This process causes those components to work less efficiently. 

Thermal cycling

As solar panels are exposed to varying temperatures over the years the electrical connections in the panel become less efficient. Energy is not able to move through the damaged soldered connections as effectively.

Damp heat

Over the years solar panels are damaged by humidity, especially when paid with high temperatures. High heat and humidity cause the insulation around the solar cells to separate. 

Humidity freeze

When water, even in trace amounts, freezes in or around your solar panels it causes the various interconnects to work less efficiently. 

Other causes for solar degradation

While the above factors are almost impossible to avoid there are two other factors that can cause your system to degrade at an expedited rate.

Light-Induced Degradation: Caused by the solar panel’s boron coating oxidizing and clouding the panels. The phenomena can quickly reduce efficiency by 1 to 3 percent.

Potential-Induced Degradation: While relatively rare in the United States, this occurs when humidity causes electricity leaks that then arc back to the system damaging the internal components. 

The main takeaway from all of these causes of degradation is that water and electricity are not good friends. 

Do solar panels go bad?

While solar panels certainly become less efficient over time they don’t have an expiration date. They can continue to generate electricity well after their expected 25 - 30 year expected lifespan. Just don’t expect them to work quite as well. 

Additionally, it is rare for solar panels to fail before their expected lifespan is complete. The National Renewable Energy Laboratory (NREL) conducted a study that found that only 5 out of 10,000 solar panels fail annually. 

That’s study included all solar panels installed since the year 2000. Since technology has increased greatly in recent years this number is likely much lower for newer solar power systems.