Solar energy is a long-term investment — but like all technology, solar panels gradually lose efficiency over time. This performance drop is known as solar PV panel degradation, and understanding it is key to estimating how much energy your system will produce over its 25+ year life.
In this blog, we’ll explain what degradation means, provide a simple year-wise efficiency chart, and share ways to slow the decline and protect your ROI.
What Is Solar Panel Degradation?
Solar panel degradation is the gradual reduction in a solar panel’s ability to generate electricity as it ages. Factors like UV exposure, temperature changes, and environmental wear cause the panel’s materials to break down slightly each year.
While degradation is normal, it’s important to choose panels with low annual loss and maintain them properly to ensure high energy output over decades.
Year-Wise Degradation Rate of Solar Panels
Most standard solar panels degrade at approximately 1% per year. This means they lose about 1% of their original capacity annually — though high-efficiency panels may degrade more slowly.
Estimated Solar Panel Efficiency Over Time
| Year | Efficiency Remaining |
|---|---|
| Year 1 | 99% |
| Year 5 | 95% |
| Year 10 | 90% |
| Year 15 | 85% |
| Year 20 | 80% |
| Year 25 | 75% |
| Year 30 | 70% |
Quick Math: A 100 kW solar system may produce around 90 kW by year 10, and 75 kW by year 25 — under the 1% per year degradation model.
What Causes Solar Panel Degradation?
Several factors contribute to a gradual drop in performance:
- UV Exposure: Constant sunlight slowly wears out internal layers
- Thermal Cycling: Repeated heating and cooling causes material fatigue
- Moisture & Humidity: Leads to corrosion or PID (Potential Induced Degradation)
- Soiling: Dust, pollen, and bird droppings accelerate wear
- Mechanical Stress: Wind, poor mounting, or heavy loads may cause microcracks
How to Reduce Solar Panel Degradation
While degradation is inevitable, you can slow it down with smart choices and regular care:
- Choose Tier-1 solar panels with proven durability and low degradation warranties
- Install dust control windfences to reduce airborne particles
- Keep panels clean with a regular cleaning schedule
- Use strong mounting structures to reduce vibration and stress
- Install PID-resistant modules in humid or coastal environments
- Monitor system output regularly to detect underperformance early
Panel Types and Degradation Comparison
| Panel Type | Typical Degradation Rate |
|---|---|
| Monocrystalline | ~0.5% – 1.0%/year |
| Polycrystalline | ~0.8% – 1.0%/year |
| HJT (Heterojunction) | ~0.25%/year (very low) |
| TopCon (Next-gen mono) | ~0.3%/year |
| Thin-film | ~1.0% – 1.5%/year |
If you’re building a solar farm or commercial plant, choosing low-degradation technology like HJT or TopCon pays off long-term.