UNE-EN 62788-1-2:2017

This international standard provides a method for measuring the volume resistivity of materials used as encapsulation, edgeseals, front-sheets, backsheets, or any other insulating material in a photovoltaic (PV) module. The test is performed on dry, humid or wet preconditioned samples. In the case of frontsheets and backsheets comprised of multiple layers, the measured resistivity is an effective value. This test is designed for room temperature measurement, but can also be utilized at higher temperatures. Degradation of PV modules is known to occur in part by electrochemical corrosion, and other potential induced degradation processes. These processes may be dependent upon the resistivity of a polymeric component. Therefore, the DC resistivity of polymeric components is relevant to module design and durability in the field. The resistivity may depend on cure state, temperature, and water content. For insulating materials, the voltage-history may affect the measured resistivity. Because of the possible effect of the voltage-history, the measurement is performed in a manner consistent with a module deployed in ideal field conditions. However, to accommodate faster throughput, a shorter, more qualitative test method has been included. Measurements obtained using either method may be used by material manufacturers for the purpose of quality control of their electrical insulating material as well as for reporting in product datasheets. PV module manufacturers may use these methods for the purpose of material acceptance, material selection, process development, design analysis, or failure analysis.This measurement method can also be utilized to monitor the performance of electrical insulating materials after weathering, to assess their durability.