The Peltier control circuit is a simple SMPS (Switched Mode Power Supply) circuit that converts the regular ac mains power supply into a regulated 12 volt dc supply required to drive the Peltier element. Fig. 4 shows hardware implementation and block diagram of the SMPS unit. The solar unit, shown in Fig. 5, consists of a photovoltaic cell, a Volume Unit (VU) meter and a 12 volt rechargeable battery to store the energy. The solar cell is connected to the VU meter which is connected to the input to the thermoelectric element. The battery is also connected to the peltier element’s input. Solar cell is a semiconductor device that converts the energy of sunlight into electric energy. These are also called ‘photovoltaic cell’. Solar cells do not use chemical
reactions to produce electric power, and they have no moving parts. Photovoltaic solar cells are thin silicon disks that convert sunlight into electricity. The usable voltage from solar cells depends on the semiconductor material.