The fabrication of GaSb infrared-sensitive photovoltaic cells designed to boost the energy-conversion efficiency in tandem solar cell stacks is reported. Located behind GaAs solar-cells in 50× concentrated light configurations, these GaSb cells will boost the stack efficiency by 6.5 percentage points for space (AM0) and 7.0 percentage points for terrestrial (AM1.5D) applications. Assuming a GaAs cell efficiency of 26.7% (AM1.5D, 50×) as recently reported, the GaAs on GaSb stack efficiency will be 33.7%. Reduced series resistance in future GaSb cells will allow tandem-stack energy-conversion efficiencies over 35%.

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It is well known that distributed combined heat and power (CHP) systems for commercial and industrial buildings are economically desirable because they conserve energy. Here, a thermophotovoltaic (TPV) unit is described that brings CHP into the home providing both heat and electric power by replacing the typical home heating furnace with a combined TPV furnace-generator. First, the design of a 1.5 kW electric /12.2 kW thermal TPV furnace-generator is described along with the key components that make it possible. Diffused junction GaSb cells are one of these key components. Secondly, an economic cost target is determined for this system where the cost of the photovoltaic array will be key to the economical implementation of this concept. Finally, it is argued that the GaSb cells and arrays can be manufactured at the required low cost. The cost target can be reached because the GaSb cells in the TPV furnace-generator can produce an electrical power density of 1 W cm −2 which is 100 times higher than the typical solar cell. The cost target can also be reached because the GaSb cell fabrication process parallels the silicon solar cell process where no toxic gases are used, no wafer polish is required and cast polycrystalline cells can be used.

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