This question is part of the Super Big Solar Panel FAQ from Solar Mango, where expert answers to over 100 important questions on solar panels are provided.


The derate factor for the PV module nameplate DC rating accounts for the accuracy of the manufacturer’s nameplate rating.

Field measurements of PV modules may show that the PV module powers are different than the nameplate rating or that they experienced light-induced degradation upon exposure (even crystalline silicon PV modules typically lose 2% of their initial power before power stabilizes after the first few hours of exposure to sunlight).

A derate factor of 0.95 represents that testing yielded power measurements at STC that were 5% less than the manufacturer’s nameplate rating.

Source: Solar Module Derate Factor from Solar Mango’s Solar Dictionary

Super Big Solar Panel FAQGet to know answers to over 100 important questions on solar panels from here.


You Might Want to Check Out these Questions Too on Risks & Warranties

  • How Much Do I Stand to Lose If I Choose a Poor Quality Solar Panel?-Here
  • Have there been Real Life Failures of Solar Panels within a Few Years after Installation?-Here
  • Can Solar Panels Withstand Hailstorms?-Here
  • Can Solar Panels Withstand Snow and Rain?-Here
  • Can Solar Panels be Damaged by Floods?-Here
  • What Happens if the Solar Panel Manufacturer Goes Out of Business?-Here
  • What Warranties Should I Look for While Purchasing Solar Panels?-Here
  • What Happens if there are Bird Droppings on Solar Panels?-Here
  • What Happens if Heavy Objects Fall on Solar Panels?-Here
  • What Happens if Someone Accidentally Walks on Solar Panels?-Here
  • What is PID (performance induced degradation) of a Solar Panel?-Here
  • How Can I Protect Solar Panels Against Monkeys and Other Animals?-Here
  • What All Can Go Wrong with Solar Panels?-Here
  • What Types of Insurance are Available for Solar Panels?-Here
  • What is the Shading of Solar Panels all About? What are Its Implications?-Here
  • What are Light Induced Defects in Solar Cells?-Here
  • If a Cell in a Solar Panel Doesn’t Work, Does It Affect Generation from Other Cells?-Here