Regher Solar proposes this SBIR project to improve the conversion efficiency of ultrathin silicon (UT-Si) solar cell technology by adding the Layer of UV CONverting coating (LUVCON) provided by SSS Optical Technologies, LLC that down-converts UV light to visible, therefore improving efficiency. At present UT-Si cells manufactured by Regher Solar have a 22% Beginning-of-Life (BOL) efficiency, which is exactly in between Copper-Indium-Gallium-Selenide (CIGS) and Epitaxial Lift Off Inverted Metamorphic (ELO-IMM) thin film solar cells that are currently considered for making flexible solar blankets. However, the End-of-Life (EOL) efficiency of UT-Si cells drops minimally when exposed to space radiation making them more attractive for the use in space since radiation damage is mitigated. This was shown in our recent NASA SBIR project. By further improving the efficiency, UT-Si cells can achieve EOL efficiency significantly higher than ELO-IMM cells while being as inexpensive as CIGS cells making them the optimal choice for flexible solar arrays.
The main proposed innovations include: (1) Develop polymer nanocomposite coatings impregnated with the nanoparticles of fluorides doped with rare earth ions to improve the conversion efficiency of the solar cell; (2) Enable radiation the coating be radiation tolerant by optimizing its composition and thickness; (3) Develop a low-cost and manufacturable process of coating to replace cover glass for space solar blankets and panels; and (4) Qualification testing of CICs and mini-blankets with LUVCON coating.
Phase II will demonstrate feasibility of the proposed innovations at the scale of the blanket and conduct comprehensive electron and proton irradiation testing. We will collaborate with blanket manufacturers to package UT-Si solar cells in CICs and blankets and conduct complete qualification to achieve TRL 6.
UT-Si solar cells with improved efficiency can be integrated into novel flexible solar array deployment systems to meet NASA solar array specific power (250 W/kg) and stowed volume efficiency (50 kW/m3) goals. UT-Si solar cells have a potential to meet NASA goals for the long-term operation in high radiation environment (1 MeV 6e15 e/cm2). Together this will make UT-Si solar cell technology an ideal choice for several NASA projects including LISA solar array, Vertical Lunar Solar Arrays and large-scale solar arrays for Solar Electric Propulsion
The main advantage of improved UT-Si technology is compatibility with high volume manufacturing and low cost. Production of improved UT-Si solar cells can be quickly scaled up to 100 MW/year to meet the demand of growing space industry. The example applications include satellite mega constellations and space based solar power that will need tens of MW of affordable space-stable solar cells.