Dependence of Multijunction Optimal Gaps on Spectral Variability and Other Environmental and Device Parameters

We present a method to calculate the yearly energy production of multijunctions including spectral variations. We use it to find the optimal band gaps yielding maximum energy production. The band gaps found are different to those previously reported when using the standard efficiency as the optimization target. Our calculations predict that novel hybrid tandems in combination with bifacial silicon can lead to energy yields near 1 MWh m−2 year−1 at most locations of interest. We also discuss the effects of changing parameters such as the external radiative efficiency, series resistance, sub-cell thickness, temperatures, and location.