Performance and testing of a low cost solar water heater cum solar cooker

Abstract Performance of a novel device which can be used as a solar water heater during winter and a solar cooker during summer has been described. The device can provide approx. 50 1 of hot water at a temperature of 55–65°C in the evening which can be retained at 40–45°C until the next morning when tap water temperature is 15–20°C. The same device can also be used as a hot box solar cooker for cooking 4 kg of dry food per day. The overall efficiency of the device as a solar water heater is 62.6% and as a solar cooker is 23.8%. The payback period of the device shows that it is economical.