Path-Q Solar

How much production loss should I expect from normal panel degradation over time?

Answer

Panel output normally declines gradually with age, but the rate varies by panel technology, manufacturing, climate, installation conditions, and the applicable product warranty. Use the specific panel's documented degradation schedule rather than a generic percentage, and distinguish panel degradation from failures or system-wide underperformance.

Key points

  • Degradation reduces the panel's maximum output over time; it does not usually cause an abrupt annual drop.
  • The panel warranty may specify an initial degradation period and a later maximum output level.
  • Heat, moisture, UV exposure, cycling, and installation quality can affect long-term performance.
  • Inverter, wiring, shading, soiling, and monitoring problems can mimic degradation.

What it depends on

  • Panel model and warranty terms
  • Climate and mounting conditions
  • System maintenance and other sources of production loss

Risks and trade-offs

  • A system may produce less than the original estimate even when normal degradation is occurring.
  • Warranty thresholds and claim procedures may be difficult to establish without reliable records.
  • Replacing panels early may not be economical if the remaining output is still useful.

Information you may need

  • Panel model and product warranty
  • Baseline commissioning data and ongoing monitoring
  • Weather, shading, soiling, and maintenance history

Your next step

What to do next

Record current production and compare it with the panel warranty's degradation schedule after adjusting for weather, shading, soiling, and equipment availability.

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SQ01320