Repair and Preventive Maintenance of PV Modules with Degrading Backsheets Using Flowable Silicone Sealant

PV modules with a degrading backsheet are a problem for the complete PV value chain. Some types of backsheets are known to develop cracks because of an aging-induced change in the mechanical characteristics of the material during operation in the field, which results in a loss of insulation resistance. In this work, we present a solution for repair and preventive maintenance based on a single component flowable silicone sealant. The method fills the cracks present in the backsheet with an insulating material, restores the insulation resistance, and provides a protective layer to avoid subsequent degradation. The solution was successfully implemented on the back of PV modules with coextruded polyamide backsheet (‘AAA’) which showed deep cracks following degradation 5-7 years of operation in a solar park. The repaired modules had a restored insulation resistance of several hundred MΩ as observed with wet leakage testing, and maintained a high resistance after accelerating aging. This repair technology can be done in the field and is an alternative solution to module replacement.