UK · London
Why are my solar panels underperforming? in London
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.
London has a maritime climate with 3.8 peak sun hoursper day. The UK's cooler temperatures benefit panel efficiency but shorter daylight hours affect annual output.
Related issues
Natural panel degradation
commonAll 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%
Cell hotspots
commonLocalised overheating in individual cells caused by micro-cracks, shading, or manufacturing defects. Best detected via thermal imaging.
Typical loss: 5–20%
Panel soiling
commonDust, pollen, bird droppings, or debris accumulation reducing light absorption. More severe in arid or agricultural areas.
Typical loss: 2–15%
Inverter efficiency loss
moderateDegradation or malfunction in the inverter reducing DC-to-AC conversion efficiency. Often indicated by error codes or unexpected shutdowns.
Typical loss: 5–25%
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Use our free Solar Loss Checker.
Check my systemBased on conservative solar performance modelling and published degradation data
Updated April 2026 · Structured performance modelling
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