Hot-water tank heated by combination of solar power and electricity has electrical resistances at half-way point and three-quarters of height from bottom

摘要

The tank, which has an overall capacity of 400 litres, is fitted with three temperature sensors, two electrical resistances (4, 5) and a solar-powered heat exchanger (6). The electrical resistances, which are positioned half-way and three-quarters of the way up the tank, are time-controlled and designed to be switched on, when necessary, at off-peak times to supplement the heat trapped from solar radiation.