California Institute of Technology (Caltech)

The use of flat-panel solar photovoltaics (FPV) is growing dramatically as costs decrease. By contrast, more efficient concentrated PV systems (CPV), which focus direct sunlight onto a single point, have not been widely adopted because of their high cost, large size, and expensive tracking systems. A new approach, micro-scale concentrated photovoltaic systems (micro-CPV), may deliver the cost and size benefits of conventional FPV systems, but with an estimated 50% performance improvement. Micro-CPV modules would use cost-effective trackers and generate more electrical power in a given area. This allows installation on space-constrained residential rooftops and decreased costs for commercial and utility applications. Finally, the MOSAIC systems would have the ability to capture both direct and diffuse sunlight, which could make CPV economical in more geographical regions. These innovations could spur the expanded use of PV to generate clean, renewable energy.

Researchers at the California Institute of Technology (Caltech) and their partners will design and fabricate a new CPV module with features that can capture both direct and diffuse sunlight. The team’s approach uses a luminescent solar concentrator (LSC) sheet that includes quantum dots to capture and re-emit sunlight, micro-PV cells matched to the color of the light from the quantum dots, and a coating of advanced materials that enhance concentration and delivery of sunlight to the micro-PV cells. In addition, the light not captured by the quantum dots will impinge on a tandem solar cell beneath the LSC sheet. The design of the LSC will focus on lowering the number of expensive micro-PV cells needed within the concentrator sheet, which will reduce system costs, but still maintain high efficiency. The design will also allow the module to be effective without any tracking system, making it potentially attractive for all PV markets, including space-constrained rooftops.

If successful, Caltech’s innovations may lower the cost of solar systems by enabling economical, high-volume manufacturing of micro-CPV arrays as well as efficient, cost-effective LSCs. Improved systems could encourage greater adoption of solar power in all three primary markets – residential, commercial, and utility.