Solar hot water systems use roof-mounted collectors to heat water stored in a tank, usually with an electric or gas booster for cloudy weather and high demand. They can reduce energy use, but suitability depends on your roof’s orientation, available space, household hot-water use and local climate. Upfront costs, maintenance and available rebates vary, so compare the system’s likely savings with its purchase and installation price. A licensed plumber or accredited solar hot-water installer can assess your home, while current rebate information is available through your state or territory government.