Illinois (IL)
Solar panel degradation rates: what to expect in Illinois
All solar panels degrade over time — it's unavoidable physics. The question isn't whether your panels are degrading, but whether they're degrading faster than expected. Published research shows median degradation rates of 0.5–0.8% per year, but real-world rates vary significantly by climate, panel quality, and installation conditions.
How Illinois's climate affects this issue
Cooler operating temperatures actually benefit panel efficiency and typically result in slower-than-average degradation rates.
Climate
cold
Sun hours
4.2 hrs/day
Soiling risk
low
Solar adoption
moderate
Related issues
Natural panel degradation
All solar panels lose efficiency over time at roughly 0.5–0.8% per year. Accelerated in extreme heat or poorly manufactured panels.
Typical loss: 3–15%
Self-check tip:
Compare current annual production to your system's first-year output. A decline beyond 1% per year may indicate accelerated degradation.
Check your Illinois solar system
Use our free Solar Loss Checker to estimate how much energy your system in Illinois may be losing.
Check my systemBased on conservative solar performance modelling and published degradation data
Updated April 2026 · Structured performance modelling
How we calculate →