Using a Hitachi evacuated tube solar collector, 1.7 m2, to preheat hot water.
This South West facing panel may collect 1500kWh per year when pre-heating water.
The 100 litre cylinder provides a solar storage volume of approximately 60 litres per m2 of panel.
When the water in the solar panel is 4o hotter than the water in the tank a 40W pump is switched on by a differential temperature sensor to transfer the heat.
An evacuated tube solar collector is designed to maximise solar energy gain during cold weather by reducing heat losses by convection and conduction. The use of a separate preheat cylinder, increases thermal efficiency during cold periods.