District solar heating. View of roof-mounted solar panels, part of a district solar heating system. Water is heated by the solar panels during the day, and passed into a storage tank. Water may be distributed throughout the district for space heating and domestic hot water. The store is large enough to keep water for autumn and winter months, and is kept hot by excellent insulation and occasional re-heating by oil-fired boilers. This scheme drastically reduces the district's dependence on oil. Photographed at Saro, Sweden.