Solar panelsMaintenance tips

How long do solar panels last? In a nutshell, quite a while

A PV system is a big investment and it takes 7-8 years to get your money back from it. Will it even survive for that long? Yes and for much longer. In this article, we’ll talk about how long do solar panels last.

Solar panels have two types of warranties

The product warranty covers the integrity of the panel itself and protects it against defects in material, premature wear and tear, as well as environmental and workmanship issues. It typically lasts between 10 and 25 years, depending on the brand. The highest it gets is 40 years with some of SunPower's solar panels. Think about it as the minimum solar panels lifespan.

This type of warranty normally does not cover the cost of labor to diagnose the problem and/or replace the equipment. Neither does it include the shipping costs to deliver replacements on-site. Contact your solar installer to learn if these costs can be covered by their workmanship warranty.

Always check the manufacturer’s warranty terms before purchasing solar equipment

The performance warranty guarantees that the panels will produce a certain amount of power for a specified number of years. Most solar panels have 25-year output warranties, but some manufacturers go further and offer three decades. Bifacial panels receive a 30-year production warranty. 

But don’t worry, you won’t necessarily need to replace them after this period is over. Read the article to find out how you can benefit from manufacturer’s warranties, what solar panel degradation means, and what to do to make your panels work for half a century.

Panels retain at least 80% of power after 25 years

The performance warranty of a solar panel often comes in two shapes. The first is a standard tiered warranty. It specifies that the module will retain at least 90% of its rated output after 10 years and at least 80% after 25 years.

Alternatively, some manufacturers provide a linear performance warranty. The power output is expected to decrease by a fixed value — the infamous degradation rate. It’s a much better offer than a tiered warranty. You often can find the performance graph in the datasheet that shows the decline of output throughout the solar panel's lifetime.

Beware of degradation! No more than 1% per year

0.8%

is the average solar panel degradation rate

The degradation rate is the rate at which solar panels lose efficiency over time. For instance, if a panel has a degradation rate of 1% per year, it will be 10% less efficient after 10 years of operation.

The average solar panel degradation rate is around 0.8%, according to the National Renewable Energy Laboratory (NREL). This metric depends on the materials and technologies used by the manufacturer and varies from 1% to 0.5%. Some premium manufacturers like Panasonic, SunPower or REC, offer degradation rates as low as 0.25%.

Solar panel degradation rates are constantly improving as solar panel technology gets better over the years. Of course, the life expectancy of a solar panel from a high-tier brand is higher than average.

First year is the toughest for panels

There is a catch to linear warranties – they are only linear starting from year 2. During the first year of operation, the performance decrease may be as high as 3%, and even the best manufacturers set the target at about 2%.

Light Induced Degradation (LID)

a loss of performance of PV modules that happens in the very first hours of exposure to the sun.

Most of the decrease happens immediately after the panels are put in operation. It’s called Light Induced Degradation (LID). The cause is silicon impurities. The microscopic fractions of oxygen actively bond with boron during the first few hours of sunlight exposure, causing most of the year one efficiency drop.

To make the idea of degradation rate crystal clear, let’s take a 300 W solar panel as an example. Given a 0.8% annual degradation rate and a 3% first-year drop, in year 2 such a panel will operate at 97% of its original output, which is 291 W. In year 3 its efficiency will be 96.2%, meaning 288.6 W output. You can multiply the degradation rate by the number of years after year 1 and subtract that number, together with the year 1 drop, from 100% to determine the projected output of your solar panels after a certain number of years

Be careful not to void your protection

Note that the manufacturer’s performance warranty is about each separate panel’s performance, not about the output of your system as a whole. Say your system is properly installed and gets adequate sunlight, but its production is below the desired output. A faulty solar panel is likely to be the cause. And this is when your manufacturer’s warranty would kick in.

A warranty will only remain in force as long as your system is designed appropriately. For example, if your inverter isn’t a good match for your system, it may short-circuit your equipment, and the warranty will not cover the damage. You may also void your warranty if you have your panels repaired by an unlicensed worker or if you accidentally step on them while walking on your roof.

Double your solar panel’s lifespan with proper maintenance

Solar panels are pretty easy to maintain because they are designed to withstand extreme weather conditions and all types of precipitation, such as snow, hail and wind. Moreover, they hardly ever need repairs since there aren’t any moving parts that could break down.

Vasilii Smirnov
Solar Installation Expert

How long can solar panels last also depends on how you treat them. Have an electrician take a look at them every now and then, keep them clean, and they’ll serve you for decades.

Even though solar panels don’t require daily spit and polish, you can extend their lifetime by routine care and quality maintenance. To maintain and extend the lifespan of solar panels, you can follow these simple rules:

50-year

solar panels life expectancy is feasible when they are properly used and maintained

• Work with a trustworthy solar installer that provides routine maintenance checks. They can alert you to any quality degradation in the panels or any issues with the racking, wiring, etc. Regular checkups have a big impact on how long solar panels last. Don’t try to disassemble a solar panel yourself when something is wrong.
• Pay attention to other elements of your solar system: inverters, batteries, optimizers, etc. Make sure they are all of matching technical characteristics and work properly without any abnormalities. Since everything is interconnected in your system, failure of any component might damage the panels.
Keep your panels clean: remove any debris and wash them with water if they are dirty. When dust or sand isn’t removed for too long, it can bring the output down and possibly cause malfunctions.

Maintenance does influence how long solar panels do last on average. The tips above will help you reduce any strain on the solar panels and ensure that your panels harvest as much sun as possible and last for decades.

With a degree in Linguistics, Tatiana uses her vast experience in technical translation to deliver complicated concepts in simple words. She joined the company in 2020 as a contributing writer to become the person to influence Blog’s development.

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