Understanding Solar Warranty
Two warranties for solar panels
Solar panel manufacturers offer two basic warranties for 1) Product Workmanship and 2) Performance Output. The guarantees are shown as 10 / 25, or 20 / 30 to reflect the length of each warranty.
The first warranty covers that the product will be free from defect. The most common is 10 years, while some brands have a 12, 15, 20 or 25-year product warranty.
There is no correlation between the length of the warranty and the build quality of the solar panel. Read more about how solar panels are made and tested.
Because solar panels will degrade over time, the second warranty covers the power output performance. The output warranty is usually 25 or 30 years. This means the brand guarantees the power output level of the panel during the warranty period.
Most commonly, the warranty is for 90% of the original rating in 10 years, and 80% in 25 or 30 years. For example, a 100 watt solar panel is guaranteed to produce 90 watts in 10 years, and at least 80 watts in 25 years.
Some companies include warranty insurance to provide confidence they will be able to honor future warranty claims. They don't offer this because they are just nice people. They offer it because it is often a requirement for very large government or commercial projects. Regardless, these companies have taken out an insurance policy to cover future claims.
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What is the warranty vs. lifespan of a solar panel system?
A solar panel lifespan is how long they will last, which will be a long time depending on the amount of active use, or the amount of sunshine converted into electricity by the solar panels, and the environment of the location. Most systems are only in use for 6 to 8 hours per day. Solar panel systems have been reported to work for 30 to 40 years.
A warranty is for the output and performance of the solar panels. Manufacturers will provide a minimum 10 year warranty on the panel workmanship, and up to 30 years on the performance output. The Balance of System (BOS) components like inverters and mounting have manufacturer product warranties from 10 to 25 years.
The performance of the solar panels will diminish over time. The panel warranties reflect this. Most solar panel warranties have a minimum performance warranty. The panel will be warranted to produce at least 90% of the rating at 10 years and 80% at 25 years. For example, a 200 watt panel would have a warranty to provide at least 180 watts of power at 10 years, and at least 160 watts at 25 years.
Regardless, solar power is a great deal. You'll enjoy a $0 or very low power bill for the 30+ year life of the system. No matter how you calculate it, you will save thousands of dollars with a solar panel system. You'll also get some great tax credits and cash rebates, and you will increase the value of your home.