Modern crystalline solar panels come with a 25 to 30-year life guarantee, but the panels won’t be performing as well after 25 years as they did in their first year.
Thisdegradation process in unavoidable, but thankfully slow, as you can’t escape UV light (especially if you’re a solar panel) and temperature cycles. Most panel warranties say they’ll be at 80% of their peak production after 25 years or so as the rate of degradation is around 0.5% to 0.7% each year. This is, of course, as long as there are no physical issues.
The unavoidable causes of degradation are UV light and the constant contraction and expansion brought about by cycles of heat and cold – daily and seasonally. The rest of the causes are more complex.
Thermal cycling can cause soldering to fail, as well as create microscopic cracks, but damp heat can seep into the panels causing encapsulated elements to split from their layers. It can also cause cells to corrode and when water freezes, it can damage junction box adhesives.
The other forces acting on your panels
There’s also potential-induced degradation (PID), which can happen when transformer-less inverters are used with the panels.
PID is caused by the different components in the same system having differing voltage potentials. This means that current can leak and modules start to lose their best game; very often, negatively grounding a system takes care of PID, but transformer-less inverters aren’t grounded.
When the current leaks, sodium ions in the glass travel towards either the solar cell of the frame, depending on which way the system’s grounded. The increasing voltages used in the solar industry are making the pull on the sodium ions stronger, which can speed up PID.
Thankfully, manufacturers are making frameless panels and making modules as PID-free as possible. When you order your system, your installer needs to know exactly which products are going into it to limit the PID degradation.
Panels are generally getting thinner and lighter, so they’re more flexible. This sounds like a good thing, but during the installation process, if the operatives are a bit heavy-handed, the flexing and jiggling about can cause microscopic cracks.
Similarly, carrying a panel on top of a hardhat, dropping it or (gasp) standing on a panel will lead to micro-cracks. These miniscule fissures won’t be an immediate problem, but will speed up the process, causing the panels to lose power at a faster rate than they should.
Use reputable installers
By choosing the best products and the best installation team you can afford you’ll mitigate the degradation process, making sure you get the best out of your panels for as long as possible.