Multijunction Concentrator Solar Cells: Analysis and Fundamentals

Abstract

Multijunction (MJ) concentrator solar cells are primarily constructed of III-V semiconductor materials. The high solar-conversion efficiencies of these devices are dependent on precise control of growth conditions using one of several techniques such as molecular beam epitaxy, metal organic chemical vapour, or metal organic vapour-phase epitaxy deposition. The use of several junctions in an MJ tandem stack allows these devices to achieve efficiencies that are not possible for single-junction devices. Their behaviour is consequently complex, but it can be understood through an examination of the external quantum efficiency and the temperature dependence of each cell in the stack. This chapter lays out a systematic approach for understanding the spectral and temperature dependence of the overall MJ device by way of consideration of its component subcells. The efficiency of the cell as a function of temperature and concentration is described for both lattice-matched and metamorphic triple-junction (TJ) solar cells. The electrical characteristics and current-voltage curves are described from these considerations, and the performance of MJ solar cells under real operating conditions are then presented by considering a term describing the overall thermal factor and another term for the spectral factor. These terms can be understood from the background presented in the previous sections. Finally, the power output for the complete cell incorporated into a Fresnel lens based high-concentration photovoltaic system is presented for a particular geographic location using meteorological data.

Simulating the Performance of Al0.3Ga0.7As/InP/Ge Multijunction Solar Cells under Variation of Spectral Irradiance and Temperature

“…is high value of solar cells efficiency under concentrated radiation has been theoretically predicted before, as can be found in Reference [24]. Although in reality, the nonidentical current model (harvesting the power from each subcell independently) seems unrealistic as compared to the identical current model, choosing this model does not change the intrinsic properties of MJSC in responding to the variation of temperature and incoming spectral irradiance.…”

A Stable Integrated Photoelectrochemical Reactor for H2 Production from Water Attains a Solar‐to‐Hydrogen Efficiency of 18 % at 15 Suns and 13 % at 207 Suns

“…Under uniform irradiance and constant temperature, the short‐circuit current density is considered linear with respect to light concentration, as expressed in Equation : …”

Ultra‐efficient intrinsic‐vertical‐tunnel‐junction structures for next‐generation concentrator solar cells

“…In this sense, the η achieved should be considered as a first step of the real potential. Materials such as GaInP, GaInAs or GaInAsP could be used to get alloys with energy gaps ranging from 0.4 to 2.3 eV 42 . Hence, it seems feasible to develop MBG i‐VTJ cells with six or more bandgaps, which shows theoretical η ≈ 60% at one sun 41 .…”