Mechanical Reliability Calculations for the Thin Specialty Glass PV Solar Panels

Abstract

This study provides important design guidance to the Photovoltaic (PV) solar panel development efforts using the finite element based computations of the PV module under the mechanical loadings. We consider specialty thin glass (Corning Eagle XG^®) as superstrate of the PV module, while a standard tempered Soda-Lime-Silica Glass (SLG) is considered as bottom support. The reliability calculations for the module were performed based on the stress magnitudes obtained from the FEA computations. The PV solar panel considered in this study are supported by C-chanel rails that run along the longitudinal direction.  The optimum values for the C-chanel rail support location and height were determined using FEA driven reliability calculations. A methodology involving back calculation of the limiting stresses from the reliability constraints is briefly discussed, that can save the time consuming FEA iterations and tedious post processing of FEA results thereafter to calculate reliability. Analysis shows that the best rail position is between 17% to 20% of the module width (L) from the edge. The channel located at close to L/5 from the free edges was found to give mechanical reliability of 99%. Rail height greater than or equal to 23.5 mm can be used to achieve 95% reliability for the heavy snow load test.  Lower modulus encapsulants such as silicone decrease the stress on top glass Eagle EG (EXG) and increase the stress on SLG (bottom glass) to a bit over the temper stress level.  The butyl perimeter seal has a minimal impact on glass stress levels.