SBIR-STTR Award

The proposed program would develop a multijunction photovoltaic system based on achieving spectrum splitting by passing concentrated sunlight through a prism. The overall objective of the phase I effort is to demonstrate the feasibility of a prism/spectrum splitting multifunction concept for constructing a photovoltaic system with an amo efficiency greater than 25% in the near term and on the order of 40% in the long term. The phase I effort will involve: design and fabrication of a prism to split the solar spectrum into two wavelength regions appropriate for Si and AlGaAs cells; fabrication and characterization of a red-enhanced Si cell and an al .27 Ga .73as cell capable of contributing to the system efficiency 8.5% and 16.5% respectively; demonstration experiments to show the feasibility of achieving an amo efficiency of 258 with Si and AlGaAs cells used with prism/spectrum-splitting; and modeling calculations for a three-cell system. At the end of phase I, it is expected that the feasibility of the prism/spectrum-splitting approach to the manufacture of two or three-cell systems, with silicon as the low bandgap cell, that exhibit an amo efficiency greater than 25%. Finally, commercialization of the technology would be done in phase III.

In the previous research, a prism/spectrum splitting multijunction concept was determined feasible for constructing a photovoltaic system. In this investigation, a prototype, modular concentrator photovoltaic system is being developed that is expected to exhibit an amo efficiency greater than or equal to 30% at the beginning-oflife. The prism/spectrum splitting approach is being utilized to couple photons of appropriate wavelengths to si, gaas, and algaas, with bandgaps of 1.12 ev, 1.42 ev, 1.90 ev, respectively. The specific spectrum splitting approach involves incident light passing through an objective prism sheet to a parabolic reflector where the dispersed spectrum is projected onto a photovoltaic array consisting of three cells. The parabolic reflector concentrates the light and focuses all photons of a given wavelength to a region on the appropriate cell. The prototype system being constructed will have an aperture of 10 cm x 25 cm, and an effective concentration of 50x. The system is expected to have power per unit area and power per unit mass ratios that are greater than 400 w/m2 and 40 w/kg, respectively. When successful, applications would include space power generation and ground-based power needs. Potential commercial applications include large power generating facilities, localized power source needs and remote power.