BrightGridSolar panels gradually lose some generating capacity as they age. This process is known as degradation. It does not mean that panels suddenly stop working; rather, their maximum output gradually declines over time.
What is solar panel degradation?
Degradation is the gradual reduction in a panel's ability to produce electricity. Manufacturers typically specify expected performance through their long-term performance warranties.
Why do solar panels degrade?
- Thermal cycling
- UV exposure
- Environmental conditions
- Material ageing
- Electrical stress
- Moisture and weather exposure
How do performance warranties work?
A performance warranty may specify that the panel will retain at least a particular percentage of its original rated output after a defined period. The exact terms differ between manufacturers and models.
| Concept | What it tells you |
|---|---|
| Initial power | Panel's rated output when new |
| Annual degradation | Expected rate of output reduction |
| Long-term warranty | Minimum performance after the stated period |
Why a drop in system output does not always mean degradation
A reduction in generation can also result from weather, new shading, inverter problems, electrical faults or dirt. Performance should therefore be evaluated against comparable conditions before assuming panel degradation.
Monitor the system, not just the panels
Long-term monitoring can help distinguish normal seasonal changes from unusual performance reductions.
Plan a long-life solar system
Compare panel performance, warranties and system design for long-term energy generation.
Explore SolarFrequently asked questions
How quickly do solar panels degrade?
Panels gradually lose output over time, with the expected rate specified by the manufacturer's performance warranty.
Do solar panels stop working after 25 years?
No. A performance warranty period does not mean the panels stop generating electricity when it ends.
Why has my solar output fallen?
Possible causes include weather, shading, dirt, inverter faults, electrical problems and normal degradation.
Should I replace old solar panels?
Not necessarily. The decision should consider actual performance, equipment condition and the cost-benefit of replacement.
Marcus Webb
Head of Engineering at BrightGrid Energy
