Achieving extensive lossless coupling of photovoltaic and thermoelectric devices through parallel connection

Photovoltaic-thermoelectric hybrid systems have received broad attention in recent years owing to the capability of achieving efficient utilization of full-spectrum solar energy. This paper investigates the lossless coupling method of photovoltaic and thermoelectric devices to address the issue of large electrical coupling losses. The properties of the photovoltaic-thermoelectric hybrid systems with three connection modes, which are electrically separated, series, and parallel, are experimentally compared under different incident power densities. The electrical-thermal interaction characteristics of the photovoltaic cell and the thermoelectric device under different connection modes are further investigated with the theoretical method. The mechanism of achieving extensive lossless coupling of photovoltaic and thermoelectric devices under parallel connection is illustrated. The results demonstrate that when the incident power density is less than 15Wcm−2, the photovoltaic and thermoelectric devices can be losslessly coupled by the parallel connection. Both electrically separated and parallel coupling systems achieve the output power of 0.85 W, while the series coupling system power is only 0.41 W under the same incident power density of 15Wcm−2. Compared with the series mode, the parallel lossless coupling method can be achieved over a broader range of operating conditions and is more stable because of the small variation of the photovoltaic maximum power voltage under the practical varying irradiation and the effect of the weakened Peltier effect.