Loss Analysis for Single Junction Concentrator Solar Cells

Single junction concentrator solar cells operate at efficiencies that are surprisingly close to their one-sun equivalents cells; for the case of GaAs the 1-sun efficiency record stands at 28.8% while under concentration it stands at 29.3%. This arises due to three effects: Firstly the AM1.5G spectrum has a stronger blue component than the AM1.5D low-AOD concentrator spectrum and hence yields higher efficiency from higher band-gap cells. Secondly the 1-sun GaAs device achieves an approximate 2% absolute efficiency increase due to the removal of the substrate; a feature that is absent from the concentrator cell. Thirdly, the difficulty of achieving front metal grid structures that are sufficiently conductive to enable peak efficiencies at several hundred suns frustrates the achievable efficiency of a GaAs solar cell.