When you install solar panels, they don’t suddenly stop working after a few years. Instead, they gradually lose efficiency over time—this is called the degradation rate.
Understanding degradation is important because it tells you how much electricity your system will produce not just today, but 10, 20, or 25 years from now.
Solar panel installation Nolambur
What Is Solar Panel Degradation Rate?
The degradation rate is the percentage by which a solar panel’s output decreases each year.
For example:
- If a panel has a 0.5% annual degradation rate, it produces
0.5% less power each year compared to the previous year
This reduction is gradual and predictable.
Typical Degradation Rates in 2026
Modern solar panels are much better than older ones.
- Standard panels: 0.5% to 0.7% per year
- High-quality panels (TOPCon, premium brands): 0.3% to 0.5% per year
Lower degradation = better long-term performance
Why Do Solar Panels Degrade?
Degradation happens due to:
- UV exposure from sunlight
- Heat stress (especially in hot cities like Chennai)
- Moisture and humidity
- Material aging
This slowly reduces the panel’s ability to convert sunlight into electricity.
Real Example: 25-Year Output Loss
Case 1: 0.5% Degradation
After 25 years:
- Remaining output ≈ 88%
- Total loss ≈ 12%
Case 2: 0.7% Degradation
After 25 years:
- Remaining output ≈ 83%
- Total loss ≈ 17%
Case 3: 0.3% Degradation (High Quality Panels)
After 25 years:
- Remaining output ≈ 93%
- Total loss ≈ 7%
What This Means in Real Life
Let’s say your system generates:
- 1,500 units/month in Year 1
After 25 years:
- With good panels → ~1,300–1,400 units/month
- With average panels → ~1,200–1,300 units/month
You still get strong performance even after decades.
First-Year Degradation (Important Detail)
Most panels experience a slightly higher drop in the first year:
- Year 1 loss: ~1% to 2%
- After that: steady annual degradation
This is already factored into manufacturer warranties.
Solar Panel Warranty Explained
Most panels come with a performance warranty like:
- 90% output after 10–12 years
- 80%–85% output after 25 years
This guarantees minimum performance, not maximum.
High-end panels often offer:
- 87%–90% output even after 25–30 years
Chennai-Specific Impact
Chennai’s climate can slightly affect degradation due to:
High Heat
- Increases stress on materials
- Makes temperature coefficient important
Coastal Humidity and Salt Air
- Can accelerate aging if panels are low quality
Dust and Pollution
- Not permanent degradation, but reduces output if not cleaned
Choosing high-quality panels and proper installation reduces these risks.
How to Reduce Degradation Impact
Choose Better Technology
- TOPCon panels → lower degradation
- High-quality brands → better durability
Ensure Proper Installation
- Good ventilation reduces heat stress
- Correct mounting prevents damage
Regular Maintenance
- Clean panels regularly
- Inspect for damage or wear
Use Quality Components
- Good inverters and wiring reduce system losses
Degradation vs Real Loss (Important Difference)
- Degradation = permanent gradual loss
- Dirt/shading = temporary loss
Many people confuse the two.
If output drops suddenly:
- It’s likely dirt or shading, not degradation
Long-Term Financial Impact
Even with degradation:
- Solar systems generate strong output for 25+ years
- Most systems recover cost in 3–5 years
- Remaining 20 years = profit
Degradation does not significantly reduce ROI
Final Verdict
- Solar panel degradation is slow and predictable
- Modern panels lose only 10%–15% output over 25 years
- High-quality panels perform even better
Simple Takeaway
- Your solar system will still produce 80%–90% of its original power after 25 years
That’s why solar is considered a long-term, reliable investment, even in Chennai’s tough climate.
FAQs
1. What is a good degradation rate?
Around 0.3% to 0.5% per year is considered good.
2. Do solar panels stop working after 25 years?
No. They continue working, just at slightly lower efficiency.
3. Does Chennai heat increase degradation?
It can slightly, but good panels are designed to handle it.
4. Can degradation be reversed?
No, it is permanent—but slow.
5. Should I worry about degradation?
Not much. It is already factored into system design and ROI.