Toward microscale Cu(In,Ga) Se₂ solar cells for efficient conversion and optimized material usage: Theoretical evaluation

We develop a model to predict the performances of microscale Cu(In,Ga) Se₂ (CIGS) solar cells under concentrated sunlight, based on the study of the influence of the window spread sheet resistance, which is the first limiting factor for concentration on CIGS solar cells. This model can be used to extract the value of the sheet resistance from simple current-voltage or electroluminescence measurements. The scaling benefits associated with the operation of microscale CIGS solar cells are studied. The optimum concentration ratio, linked to the best efficiency, is calculated for different cell sizes. It is predicted that an increase from 20% efficiency, for current CIGS solar cells under 1 sun illumination, up to 30% efficiency can be expected for microscale cells under concentrated sunlight.