40 Percent Air Mass Zero Efficiency Solar Cells for Space Applications

ABSTRACT:We propose an ultra-low profile hybrid CPV concept that combines multi-junction (MJ) CPV cells capable of 40% efficiency at 1 sun with a low-cost single-junction PV backplane in a design that is lightweight, based on concentration ratios >100X and has a panel thickness 500 W/kg and a wide acceptance angle of >4.0. The low-profile design, combined with world record performance, will yield W/m3 metrics that are unprecedented for space photovoltaics. Use of concentrating optics enables dramatic (order of magnitude) cost savings through reduction in III-V material usage, while also improving radiation shielding. Rigidity is provided by the lens array combined with a lightweight honeycomb composite. Key innovations include: (1) low profile optics using monolithic, ultra-thin, lightweight lens arrays; (2) microscale 6 junction solar cells with 40% efficiency (AM0) at 1sun and high concentration efficiency of >46%, which are stacked by (3) micro-transfer printing directly onto (4) COTS c-Si cells. The use of larger area c-Si allows the design to generate power without solar tracking. This capability is important during deployment and mitigates the risks associated with a loss of tracking accuracy.BENEFIT:The research and development will produce light-weight solar arrays with significantly higher specific power densities (W/m3, W/m2, W/kg) and lower costs than what is available at present or is anticipated to be available in the foreseeable future. Concentrator configurations increase the radiation hardness of the solar arrays of the research and development. The outcome of the proposed work is expected to be applicable for solar power generation in commercial spacecraft.