Which solar panel brands have the best warranties on the market?
The majority of solar panels on today`s market come with a 25-year long warranty (also known as a performance guarantee). In most cases this means a guaranteed electrical production for 10 years at 90% of rated power output and 25 years at 80%.
JA Solar, First Solar, Canadian Solar, Sanyo, Sharp and most other solar panel manufacturers uses this standard model of degradation in their warranties. However, some manufacturers set themselves apart from the competition by offering better performance guarantees:
- SunPower has recently updated their warranty (April 1st, 2013) and guarantees 95% of rated power for the first 5 years, declining by no more than 0.4% per year the following 20 years. This means SunPower guarantees 87% of rated power output at 25 years – by far the best warranty on the market.
- Yingli Solar`s Panda solar panels guarantees 82% of rated power output at 25 years.
- SolarWorld and Trina use linear performance guarantees (see graph below).
Note that these are the best warranties these manufacturers offer (e.g. the guaranteed power output of Trina Solar`s polycrystalline solar panels are slightly lower than those that are based on monocrystalline).
What happens after my warranty expires?
We don`t really have a lot of data on what will happen to the performance of solar panels 30-40 years down the line. Chances are that your solar panels will keep generating a significant amount of electricity and bring in savings for many years after the warranty expires.
For more information on solar panel life expectancy, go to Lifespan of Solar Panels.
If you`re calculating how much power your solar panels will produce yourself, don`t forget to take into account that their output will decrease with time.