An electrical supply controller has a switch 9 for selectively coupling and decoupling an electrical supply 3 to a hot water immersion heater 11. A first current sensor 19 detects when an electric current delivered from a renewable source of electricity 2, such as a photovoltaic panel, exceeds a first threshold current. A first wireless transmitter 22 transmits a first signal in response to the electric current exceeding the first threshold current, and a wireless receiver 25 is arranged, in response to receiving the first signal, to cause the switch 9 to couple the electrical supply 3 to the output. A second current sensor 20 detects when an electric current delivered to an electrical device, such as a kettle, exceeds a second threshold current. A second wireless transmitter 23 transmits a second signal in response to the second current sensor 20 detecting the electrical current exceeding the second threshold current. In response to receiving the second signal, the wireless receiver causes the switch to decouple the electrical supply 3 from the hot water immersion heater 11.
|Published - 24 Jul 2013