A less known defect could occur on your solar panels: the backsheet degradation. Less visible than other well-known defects as hot spots, PID, corrosion or cracks, but with similar consequences: premature degradation of solar panels, thus affecting the LCOE.

The backsheet is a significant material of the solar panel. It is the last layer at the bottom of the PV module and is made up of a combination of polymers. It protects solar panels against environmental damage (ultra-violet radiation, humidity and vapor penetration, dryness, wind, dust and sand) and ensures that panels remain electrically insulated. The backsheet must have three critical properties in order to be protected for 25 years : weather ability, mechanical strength and adhesion.

Premature degradation of backsheets show up in waves and could be explained by the incredible expansion of the PV industry over the past decade (6 GW to more than 110 GW). The industry had to decrease the production cost of solar panels by using cheaper materials or through reducing the manufacturing time. A poor quality solar backsheet can thus cause:

  • system degradation
  • extra costs maintenance
  • replacements related to additional costs (claims, laboratory tests).

This degradation can be visible to the naked-eye and can take different forms. For instance, little cracks inside the sheets or white powder can be easily observed.

By Alison Aguile