Solar hot water can reduce electricity or gas use, but its value depends on your household’s hot-water demand, local climate, energy prices and installation costs. Solar thermal systems use roof-mounted collectors and a storage tank, while heat-pump systems use electricity to move heat from the air and can suit homes with limited roof space. Most systems include electric or gas boosting for cloudy periods, so they are not completely independent of the grid. Federal incentives and state programs may be available, but eligibility and amounts can change; check energy.gov.au and obtain advice from a licensed installer.