Panels lose a little output every year. Australian buyers should read degradation curves beside performance warranties — and remember that heat, shade, and soiling often move the needle more than laboratory wear in early years.
What manufacturers usually promise
Many modules specify a first-year drop then an annual maximum degradation, landing around a guaranteed percentage of original output at year 25. That is a floor for claims, not a prediction of your exact roof.
| Year band | What to watch | Owner action |
|---|---|---|
| 0–2 | Install quality, early failures | Monitoring baselines |
| 3–8 | Soiling, shade growth, FIT changes | Habit and tariff retunes |
| 9–15 | Inverter age, connector wear | Service plan; extension decisions |
| 15+ | Performance vs warranty curve | Evidence pack if claiming |
- Store the performance warranty PDF with serials
- Avoid mixing unmatched old and new modules carelessly
- Treat sudden drops as faults, not “age”
- Budget inverter replacement inside the panel life
Slow degradation is expected; sudden silence is a fault.
When replacement beats endurance
If an inverter and optimisers need work and the roof needs sheeting, a redesign may beat patching a tired array. Run the numbers; nostalgia is not a yield strategy.
Resale storytelling
Buyers like monitoring histories. Fifteen years of tidy data supports price better than a verbal “it still works.”