MULTIJUNCTION SOLAR CELLS WITH OVER 40 EFFICIENCY AND FUTURE DIRECTIONS IN CONCENTRATOR PV

摘要

Recent advances in III-V multijunction solar cell design for terrestrial use have resulted in newheights in photovoltaic efficiency. Metamorphic, or lattice-mismatched, GaInP/ GaInAs/ Ge 3-junction cells havereached 40.7% efficiency under the standard reporting spectrum for terrestrial concentrator cells (AM1.5D, low-AOD, 240 suns, 25°C). This is the first solar cell to reach over 40% efficiency, and is the highest independentlycertified solar conversion efficiency yet demonstrated for a photovoltaic device. Lattice-matched 3-junction cellshave now been measured with 40.1%, also passing the 40% milestone. Electrical and optical measurements of thesefirst cells with over 40% efficiency are presented and analyzed as a function of concentration. Cell efficiency data ispresented for production terrestrial concentrator cells at Spectrolab, incorporating many high-efficiency devicestructures. The impact of very high cell efficiency on overall PV system costs is analyzed, mapping out a route tolarge-scale, cost-effective implementation of concentrator photovoltaics, at the GW/year production level and higher.Finally, we look at where cell technology can go from here, with novel solar cell architectures that have the potentialto reach 45%, or even 50%-efficient terrestrial concentrator solar cells.