Illinois (IL)
Why are my solar panels underperforming? in Illinois
Solar panel underperformance is more common than most owners realise. Over time, every system loses some efficiency — but the question is how much, and whether the loss is within normal range or a sign of a fixable problem. Here are the most common causes of solar energy loss and what you can do about each one.
How Illinois's climate affects this issue
Cold climates have lower hotspot risk overall, but freeze-thaw cycles can worsen existing micro-cracks that lead to hotspots. Regular rainfall helps manage soiling naturally, though pollen, bird droppings, and mineral deposits still accumulate. Cooler operating temperatures actually benefit panel efficiency and typically result in slower-than-average degradation rates. Inverter lifespan in this climate is generally in line with manufacturer specifications, provided the unit is properly ventilated.
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.
Cell hotspots
Localised overheating in individual cells caused by micro-cracks, shading, or manufacturing defects. Best detected via thermal imaging.
Typical loss: 5–20%
Panel soiling
Dust, pollen, bird droppings, or debris accumulation reducing light absorption. More severe in arid or agricultural areas.
Typical loss: 2–15%
Self-check tip:
Visually inspect panels from ground level. If you can see a visible film or debris, cleaning may restore 2–7% production.
Inverter efficiency loss
Degradation or malfunction in the inverter reducing DC-to-AC conversion efficiency. Often indicated by error codes or unexpected shutdowns.
Typical loss: 5–25%
Self-check tip:
Check your inverter display for error codes or red/amber warning lights. Compare current output to the inverter's rated capacity.
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
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