BSI PD IEC TS 62788-5-2:2020

This part of IEC TS 62788 provides guidelines to assess the ability of an edge seal to prevent moisture ingress from the edges of PV modules. This document does not cover frame adhesives (sometimes colloquially referred to as edge seals) which by design do not serve to prevent moisture ingress to a meaningful degree. Edge seals should keep moisture out, remain adhered, and maintain electrically insulation from the environment. Much of the testing can be done on the material level, but given the fact that there are multiple surfaces, materials interactions, and mechanical stresses, testing on mini modules or modules is necessary. To accomplish this, this document contains three types of test sample types, materials, mini-modules, and full-size modules. It is intended that a quick evaluation and comparison can be made using materials only. This would be followed up by more rigorous tests using mini-modules where all the interfaces are correctly represented. And finally, full-size module tests are used to evaluate the actual construction process to allow unanticipated concerns to be addressed.

This document is structured to evaluate the ability of an edge seal and the overall packaging design to prevent moisture ingress and to provide sufficient electrical insulation according to accepted qualification standards. It seeks to uncover inadequacies in the permeation properties of the edge seal, electrical safety issues, or delamination resulting in moisture ingress. Here it is implied that mini-modules and full-size modules are constructed in accordance with IEC 61730 series This document does not attempt to evaluate the predicted service life of a module with respect to overall performance. It is designed to determine at the material level if the edge seal can keep moisture out, and then to uncover potential failure modes and/or evaluate the probable effect of manufacturing changes on the performance of edge seals. Test conditions focus on stresses likely to produce safety, moisture ingress, and debonding related failure modes.

For the purposes of this document, an edge seal is defined as a polymeric material designed to be placed between two impermeable (or extremely low permeability) frontsheet and backsheet materials to restrict moisture ingress from the sides. In some cases, an encapsulant with a diffusivity much lower than is found in polyethylene-co-vinyl acetate (EVA) may also serve the purpose of an edge seal and may be evaluated according to this document for comparison.

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