Technical and economic issues for gallium antimonide based thermophotovoltaic systems

Abstract

Most of the research in thermophotovoltaic systems to date has involved silicon cells as the photovoltaic converter. Recent developments in gallium antimonide (GaSb) cells create an alternative device which offers similar high efficiencies (exceeding 25%) at much lower emitter temperatures (1600 °C for GaSb vs 2300 °C for Si). System level concerns are more easily (less expensively) managed at lower emitter temperatures; however, the photon flux density at the cell diminishes exponentially with temperature. The cells’ power density (W/cm2) diminishes as the emitter temperature is reduced, raising the system power cost ($/W) for a fixed cell cost ($/cm2). A comparison of the cell component of power cost is made for thermophotovoltaic systems using GaSb and silicon cells over a range of emitter temperatures. Cost estimates are made for GaSb and silicon cells, using the burdened costs of silicon foundries for various semiconductor processing steps. These calculations indicate that GaSb cell cost per watt is lower for low emitter temperatures, and that silicon cell cost per watt is lower for high emitter temperatures. The cell component costs are roughly equal at 1500 °C, at an estimated cost of $400/kW.