How long do solar panels really last?
A properly installed Tier-1 solar panel will still be producing at least 80 to 85 percent of its original output after 25 years and will keep generating for years beyond that. Here is how panel degradation, warranties and lifetime really work.
A properly installed Tier-1 solar panel will still be producing at least 80 to 85 percent of its original output after 25 years and will keep generating for years beyond that. Here is how panel degradation, warranties and lifetime really work.
The short answer
Solar panels do not die at a fixed end date. They degrade slowly, losing a small percentage of their output every year. The industry standard performance warranty guarantees a minimum output at year 25, typically 80 to 85 percent of original. Real-world panels often beat their warranty curve.
What degradation actually looks like
A typical Tier-1 panel loses around 2 to 2.5 percent of output in its first year and then about 0.4 to 0.5 percent per year after that. Over 25 years that compounds to a panel still doing well over 80 percent of what it did on day one. The difference between a budget panel and a premium one is partly that degradation curve: premium panels lose less, slower.
The two warranties on every panel
Product warranty
Covers manufacturing defects: a faulty cell, a delaminating backsheet, junction box failure. Strong Tier-1 manufacturers offer 25 to 30 years of product warranty as standard.
Performance warranty
Guarantees a minimum percentage of original output at a given year. If your panels drop below that line within the warranty period, they get replaced.
What can shorten a panel life in real life
- Hail damage (rare in the UK, panels are tested to withstand it)
- Roof leaks that damage panel mounting (this is an install quality problem, not a panel problem)
- Poor cable management that lets connectors corrode
- Pigeons nesting under the array if bird mesh was not fitted
What about the inverter?
Inverters work harder than panels and have shorter lives. A good string inverter lasts 10 to 15 years. Most homes will replace the inverter once during the lifetime of the panels. Inverter warranties of 10 to 12 years are standard, and extended warranties are available for most models.
What about batteries?
Modern lithium-iron-phosphate batteries are warrantied for around 10 years and a defined number of full cycles. They degrade like panels: slowly, predictably, and well within the warranty curve for a typical home that cycles them once a day.