A natural circulation solar water heating system of 750 litres capacity has been designed, developed and tested. The solar collector is based on the thermosyphon principle and can provide hot water at a temperature of 80–85°C by the late afternoon. If this is stored until the following morning its temperature is still 70–75°C. The overall efficiency of the solar collector is 43%. The simple payback period for the system is between 7 months and 27 months, depending on the cost of alternative fuels.