UNE-EN IEC 62788-1-7:2021

IEC 61215-2 Terrestrial photovoltaic (PV) modules Design qualification and type approval Part 2: Test procedures already provides a set of qualification tests that indicate that the module design is likely to be free of flaws that will result in early module failure. However, IEC 61215-2 does not address long term wear-out of PV modules. This part of IEC 62788-1 is designed as a more rigorous qualification test, using accelerated stress testing to identify the potential to suffer a loss of transmittance in the polymeric encapsulant or polymeric frontsheets (as defined in 61730-1) used on the incident side of PV modules. IEC 61215-2, already includes a UV Preconditioning test, however, the parameters for that test only represent a limited level of exposure (~weeks of UV dose). This test procedure applies stress factors at a greater intensity (designed relative to Phoenix, AZ), greater fidelity (relative to the terrestrial solar spectrum), and level of exposure (~months of UV dose) using representative coupon specimens, so that the material wear out and corresponding risk of use for the transparent polymer examined may be managed relative to the benchmark location. The quantitative correlation between climate (or location of use), a specific application (utility-installation, residential-installation, roof-mount, rack-mount, use of a tracker, the system electrical configuration and its operation), and the test may be established for each specific packaging material - which is beyond the scope of this document.

This method described in this document applies to transparent packaging materials (i.e., encapsulant, frontsheet, or transparent backsheet). In the case of optically transmitting polymeric materials used on the back of a bifacial module, they are considered in this part of IEC 62788-1 to be a frontsheet. The method here is intended to qualify transparent materials for use in a PV module. This method, however, does not cover incompatibilities with other packaging materials. This part of IEC 62788-1 covers PV technology constructed using a transparent incident surface / encapsulant/ photovoltaic device construction, the relevance to other geometries where the encapsulant layer may be located behind the photovoltaic device layer, is outside the scope of this part of IEC 62788-1. In the case of bifacial cell technology, the module can accept light from its front and back surfaces the transmittance of frontsheet, encapsulant, and transparent backsheet (if used) is relevant for both active surfaces. Thin coatings that might be added for antireflection or antisoiling purposes are outside the scope of this part of IEC 62788-1. Both open rack mount and roof mount applications are considered in this part of IEC 62788-1.