What Is Solar Panel Degradation? (And Why It Happens)
Solar panel degradation is the gradual decline in power output that occurs as panels are exposed to outdoor conditions over time. All solar panels degrade — it's a normal part of their lifecycle. The key question is: how fast?
Degradation is caused by several factors:
- Light-induced degradation (LID): Occurs in the first few hours/days of sunlight exposure. Modern panels have minimized this to <1% initial loss.
- Potential-induced degradation (PID): Caused by voltage differences between the panel and grounding. Affects panels in large strings (common in commercial systems, less in residential).
- UV exposure: Long-term exposure to ultraviolet light gradually breaks down the panel's encapsulation materials.
- Thermal cycling: Daily heating (day) and cooling (night) causes expansion and contraction, which can create micro-cracks in solar cells.
- Humidity and moisture: Over decades, tiny amounts of moisture can penetrate the panel's sealing, corroding the electrical connections.
Average Solar Panel Degradation Rates by Brand (2026 Data)
The following table shows real-world and warranty-based degradation rates for major solar panel brands. Data is based on NREL studies, manufacturer warranties, and independent testing.
| Brand & Model | Annual Degradation | Output at Year 25 | Warranty Guarantee |
|---|---|---|---|
| SunPower M-series | 0.25%/year | 93.8% | 92% at 25 years |
| REC Alpha Pure-R | 0.25%/year | 93.8% | 92% at 25 years |
| Q Cells Q.TRON | 0.4%/year | 90.5% | 89% at 25 years |
| Canadian Solar HiKu6 | 0.45%/year | 89.0% | 88% at 25 years |
| Jinko Tiger Neo | 0.45%/year | 89.0% | 88% at 25 years |
| Generic/Tier-3 panels | 0.6–0.8%/year | 84–88% | 80–85% at 25 years |
Year-by-Year Degradation: What To Expect (25-Year Timeline)
Here's what a typical solar panel (0.5% annual degradation) looks like over 25 years:
| Year | Power Output (% of New) | Cumulative Degradation | Remaining Warranty Coverage |
|---|---|---|---|
| Year 1 | 99.5% | -0.5% | Within warranty |
| Year 5 | 97.5% | -2.5% | Within warranty |
| Year 10 | 95.0% | -5.0% | Within warranty |
| Year 15 | 92.5% | -7.5% | Within warranty |
| Year 20 | 90.0% | -10.0% | Within warranty |
| Year 25 | 87.5% | -12.5% | Warranty ends (typically 80–92% guaranteed) |
| Year 30 | 85.0% | -15.0% | Beyond warranty (panel still works!) |
Do Solar Panels Ever "Die" Completely?
Solar panels rarely fail completely (to 0% power) within 30 years. Instead, they gradually produce less power. Most panels installed in the 1990s and early 2000s are still producing power today — just at 70–85% of their original capacity.
Complete panel failure can happen due to:
- Micro-cracks: Tiny cracks in solar cells (from hail,installation stress, or thermal cycling) can grow over time and disconnect portions of the panel.
- Delamination: The protective backing separates from the solar cells, allowing moisture in (rare in modern panels).
- Junction box failure: The electrical box on the back of the panel fails (this is usually repairable).
- Extreme weather: Hurricanes, hail >1 inch diameter, or falling trees can physically destroy panels.
How to Maximize Your Solar Panel Lifespan (5 Pro Tips)
- Choose panels with a low degradation rate: Paying slightly more for SunPower or REC panels (0.25% degradation) vs budget panels (0.7% degradation) can mean 10%+ more power after 25 years.
- Keep panels clean: Heavy soiling can cause "hot spots" that accelerate degradation. Clean panels 1–2 times per year.
- Ensure proper racking/inverter sizing: Over-sized inverters can "clip" (waste) power and stress the system. Undersized inverters cause the system to run at lower efficiency, which does not directly cause degradation but reduces overall value.
- Avoid partial shading: Chronic shading (from trees or chimneys) can cause micro-inverter or optimizer failure over time. Use microinverters or power optimizers to minimize this risk.
- Monitor your system: Catching a failing panel or inverter early (via your monitoring app) can prevent further damage. Most panel failures are partial, not complete.
When Should You Replace Solar Panels? (Economic Analysis)
Most homeowners do not need to replace solar panels after 25 years. Even at 80–85% of original power, the panels are still producing valuable electricity. However, you might consider replacement if:
- Your electricity rates have risen dramatically and you want to increase production with newer, more efficient panels.
- A large portion of your array (30%+) has failed or degraded below 70%.
- You are adding a battery and want to maximize solar production to charge it.
- You plan to stay in the home 20+ more years and want to reset the 25-year warranty clock.
Frequently Asked Questions About Solar Panel Degradation
📊 Calculate Your Solar Savings Now
Every home is different. Use our free calculator to see how much you can save with solar in your state.
Calculate My Solar Savings →❓ Frequently Asked Questions
Most modern solar panels degrade by 0.3%–0.8% per year. Premium panels (SunPower, REC) degrade at 0.25%–0.3% per year. Budget panels degrade at 0.5%–0.8% per year. After 25 years, expect 82%–93% of original power.
Rarely. Solar panels gradually produce less power but rarely fail completely within 30 years. Panels installed in the 1990s are often still producing 70–85% of their original power today.
The performance warranty guarantees the panel will still produce at least X% of its original power after 25 years (typically 80–92%). The product warranty covers manufacturing defects (typically 10–25 years).
Not usually. Even at 80% power, the panels still produce valuable electricity. Consider replacement only if a large portion has failed, or if your electricity rates have risen dramatically and you want newer, more efficient panels.
SunPower M-series and REC Alpha Pure-R have the lowest degradation rates (0.25% per year). This means they'll still produce 93.8% of original power after 25 years.
Cleaning prevents 'hot spots' caused by heavy soiling, which can accelerate degradation. Clean panels 1–2 times per year in most climates, more often in dusty areas.