Siddons Solarstream heat pumps "capture" and thermally magnify the ambient temperature of the air to create hot water. They typically use only about 1/4 of the electrical energy of a conventional resistive element hot water service. Heat pumps are an excellent choice where direct solar radiation is poor and no reticulated gas service is available. They attract very substantial rebates from Sustainability Victoria (up to $2,500) plus REC's of around $1,200-1,500 making the 264 litre model almost free!