Semiconductors which are essentially silicon based devices or cells that convert sun light to electricity directly are called Solar Photovoltaics (SPV). The silicon employed in the SPV cells is crystalline in nature. Crystalline silicon is further classified as single crystal (sc-Si) which is also referred to as monocrystalline and poly or multicrystalline (mc-Si). These crystalline silicon based cells which have nearly 90% market share of the commercially deployed modules and arrays. These modules are also called as Flat Plate PV. Crystalline silicon cells currently offer the highest conversion efficiency, which in 2010 is 16% and is expected to reach 25% or greater by 2030 and >40% by 2050. Advances in materials and use of hybrid systems along with improvements in junction performance are expected to yield even higher efficiencies. GREPI is evaluating use of both inorganic and organic based coatings to increase the conversion efficiency of cells.
An alternative to Flat Plate PV is thin film technology. Both amorphous silicon (a-Si) and hybrid of crystalline and amorphous called micromorph (a-Si/μc-Si) silicon have been used in thin film panels. Amorphous silicon (a-Si) is both less expensive and has slightly lower efficiency of the order of 12-14%. A major advantage of thin films is it uses less material unlike the c-Si based Flat Plate PV. Thin films made of type II-IV materials are also becoming popular. Some of the films using these materials are Cadmium-Telluride (Cd-Te), Cadmium-Indium-Gallium-Diselenide (Cd-In-Ga-Se), Cadmium-Indium-Diselenide (CIS). GREPI is also developing an eco-friendly method for the manufacture of CIS based thin films.
Another active area of research and collaboration for GREPI has been in the field of storage using our proprietary nanotechnology based systems.