Solar hot water – a smart choice.  
Water heaters are one of the largest users of household energy. Heating water in an average house will use between one fifth and a third of all energy consumed in the home, and that costs a lot of money. A smart way to reduce the cost is to install a solar water heater. Instead of using just electricity or gas, solar water heaters first use the sun's rays to heat water. If the sun cannot deliver enough energy to heat all the water you need, such as on very cloudy days, particularly in winter, then electricity or gas can be used to boost the supply of hot water from the solar water heater.
Although a solar water heater costs more to buy and install than a conventional gas or electric water heater, in many country the savings in ongoing energy consumption can pay back the higher purchase cost in as little as 4 years. This not includes allowance for the cost of boosting energy from the government.
Solar is a cheaper alternative than electricity and gas for heating, and is also a greener choice (no carbon dioxide emitted per useful energy unit).