PV cells have a lower efficiency at low irradiance level. The irradiance loss with respect to 1000 W/m² may vary for different PV modules brands and manufacturers. A typical specification is, for example:

Low Irradiance Performance Specification

The typical efficiency at 200 W/m2 in relation to 1000 W/m2 (25°C, AM 1.5) is at least 97% of STC efficiency.

The computer programs developed by EcoSmart calculate the low irradiance efficiency hour-by-hour.  The results vary case-by-case.  Assuming 97% efficiency at 200 W/m2 and 100% at 1,000W/m2, a typical  average Low Irradiance Performance Factor is  around 1%.


Other performance factors

  1. GHI to POA ratio
  2. Far shading
  3. Inter-shading
  4. IAM
  5. Soiling
  6. Snow
  7. Low irradiance
  8. Temperature
  9. Module quality
  10. Mismatch
  11. Inverter efficiency
  12. Power clipping
  13. Wiring
  14. Transformer
  15. Dispatch
  16. PID
  17. Light soaking
  18. Aging