Spectral efficiency scaling of performance ratio for multijunction cells

Understanding the scaling of HCPV (highly concentrated photovoltaics) MJ (multi-junction) cell (PR) performance ratio is a key for targeting development to reach grid parity with conventional energy sources. This PR scaling for MJ cell HCPV must be evaluated for conditions present in a terrestrial use case, including limitations due to temporal solar resource variation, and MJ cell fabrication tolerances. The effect of spectral mismatch on PR scaling by the figure of merit of weighted average cell efficiency ¿_spectral is investigated. Idealized MJ cells are investigated using field spectra from Golden, CO from 2002 to 2007 to establish potential PR scaling vs. junction count. Several specific instances of known and proposed junction sets are analyzed to provide a baseline for the material constraints applicable in the near term to HCPV MJ cells. Finally, the ¿_spectral of multi-terminal 3J cells with present day bandgaps is computed.