Thermophotovoltaics developed at U-M can recover significantly more energy stored in heat batteries To measure the power produced by his photovoltaic cells, Roy-Layinde holds a heat source held over the photovoltaic cell, which emits the infrared radiation that the cell converts into electricity. Wires connected to the photovoltaic cell run the electricity to a sensor that reads the voltage and amperage. Image credit: Brenda Ahearn, Michigan Engineering. Closing in on the theoretical maximum eff...