Can I trust my Solar PV panel warranty?
Solar panels come with two different warranties: performance and product.
Product warranty: This guarantees against any manufacturing defects, i.e. physical faults with the panels. Mostly 10-25 years long, these warranties usually offer a replacement panel or refund the cost of a replacement panel but don’t cover scaffold, installation or the investigation to find the fault in the first place, which can be the most expensive part of all.
The exception (again) is Sunpower, who offer a 25-year product warranty covering the full cost of replacement, including sending a replacement panel, labour and scaffold or other access requirements.
Performance warranty: Sometimes called degradation warranties, these guarantee how much power a Solar PV panel will retain after 25 years. All warranties promise their panels will retain at least 80% of their power after 25 years. Some manufacturers offer better warranties that guarantee more than 90% of their power after 25 years. Check the panels datasheet for details.
Guaranteed for 25 years? Beware of ’25-year warranties’ as some Solar Sales people point to the 25-year degradation/performance warranty, while the product warranty may only be 10 years. If you have a ‘degradation’ issue in year 11, you may find the manufacturer blames the product, which is now out of warranty.
Other degradation: The remaining issues that cause degradation are much smaller but still contribute to the overall loss of power from panels. These are less prominent in better quality panels which have better quality components and sealants.