abstract: Silicon photovoltaics (PV) is approaching its theoretical efficiency limit as a single-junction technology. To break this limit and further lower the PV-generated levelized cost of electricity, it is necessary to engineer a silicon-based “tandem” technology in which a solar cell of another material is stacked on top of silicon to make more efficient use of the full solar spectrum.
This dissertation understands and develops four aspects of silicon-based tandem PV technology. First, a new “spectral efficiency” concept is proposed to understand how tandem cells should be designed and to identify the best tandem partners for silicon cells. Using spectral efficiency, a top-cell-design guide is constructed for silicon-based tandems that sets efficiency targets for top cells with various bandgaps to achieve targeted tandem efficiencies.
Second, silicon heterojunction solar cells are tuned to the near-infrared spectrum to enable world-record perovskite/silicon tandems both in two- and four-terminal configurations. In particular, for the 23.6%-efficient two-terminal tandem, a single-side textured silicon bottom cell is fabricated with a low-refractive-index silicon nanoparticle layer as a rear reflector. This design boosts the current density to 18.5 mA/cm2; this value exceeds that of any other silicon bottom cell and matches that of the top cell.
Third, “PVMirrors” are proposed as a novel tandem architecture to integrate silicon cells with various top cells. A strength of the design is that the PVMirror collects diffuse light as a concentrating technology. With this concept, a gallium-arsenide/silicon PVMirror tandem is demonstrated with an outdoor efficiency of 29.6%, with respect to the global irradiance.
Finally, a simple and versatile analytical model is constructed to evaluate the cost competitiveness of an arbitrary tandem against its sub-cell alternatives. It indicates that tandems will become increasingly attractive in the market, as the ratio of sub-cell module cost to area-related balance-of-system cost—the key metric that will determine the market success or failure of tandems—is decreasing.
As an evolution of silicon technology, silicon-based tandems are the future of PV. They will allow more people to have access to clean energy at ultra-low cost. This thesis defines both the technological and economic landscape of silicon-based tandems, and makes important contributions to this tandem future. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018
| Identifer | oai:union.ndltd.org:asu.edu/item:48464 |
| Date | January 2018 |
| Contributors | Yu, Zhengshan (Author), Holman, Zachary C (Advisor), Zhang, Yong-Hang (Committee member), Bowden, Stuart G (Committee member), King, Richard R (Committee member), Arizona State University (Publisher) |
| Source Sets | Arizona State University |
| Language | English |
| Detected Language | English |
| Type | Doctoral Dissertation |
| Format | 205 pages |
| Rights | http://rightsstatements.org/vocab/InC/1.0/, All Rights Reserved |
Page generated in 0.002 seconds