Optical losses and durability of flawed Fresnel lenses for concentrated photovoltaic application

Recycling optical devices and materials for solar concentrator devices is a relatively unstudied area but one which is likely to grow in importance as we progress towards an increasingly sustainable and minimum waste environment. As such, considerations into major optical flaws are required. Here, we have investigated the durability of a cracked Silicon on Glass (SOG) Fresnel lens incorporated as the primary optical component in a concentrated photovoltaic (CPV) application. Optical and electrical characterisations of the flawed glass have been conducted to show the effect on the performance. The optical characterisation has shown a drop of 3.2% in optical efficiency. As well, I-V and power curves of cracked and non-cracked Fresnel lens were compared to shows a drop of 3.2% in short circuit current (Isc) and power. The results have confirmed that the power loss is directly related to only the area of the primary optic flawed, which has been calculated through as a percentage of geometrical loss (a form of shadowing) which was estimated to be 2.7% of the concentrator area. From the results, we can confirm that although the performance has slightly declined for the significantly flawed Fresnel lens, there are no other detrimental optical effects. The durability of such optics still needs to be tested, but from these results, we recommend that similarly critically flawed optics can be utilised, likely in non-demanding singular CPV units where <5% loss is acceptable.