Efficiency by Recourse to Tandem PV Cell Systems

INCREASING EFFICIENCY BY RECOURSE TO TANDEM PV CELL SYSTEMS 

Wolf which shows the losses occurring in silicon solar cells exposed to AMO sunlight. Two large losses occur because of poor utilization of solar photons. Twenty-four percent of the energy in the 

EXCESS PHOTON n-7 ENERGY NOT UTILIZEO IN CONVERSION PROCESS 

Some calculation of the efficiency of such tandem cell systems was first conducted by Jackson in 1955. A more complete calculation was recently (1979) published by Gokcen and Loferski, and we shall focus on the results of that paper. Their calculation is applicable to solar cells in which the reverse saturation current 

This means that I must be determined by thermal generation processes, as in the classical Shockley diode, and not by tunneling or interface recombination processes which do not, in. general, depend on E. Thus, although their calculation is made for p/n homojunction solar cells, it applies equally well to p/n heterojunctions, MIS or SIS cells in which I depends exponentially on the energy gap of the photovoltaically active semiconductor. 

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