Martin Diessner

Have been thinking about this for a while, and finally got my head around to actually do it: Most of our electricity is being used to power geysers that heat up water for our daily shower(s) and other use of warm water. From an environmental point of view, there are a couple of problems:

1. The geyser is in most houses completely over-speced e.g. we have 2x 200 liter geysers and 1×150 liter for our guest house.
2. Unless you have kids, you would typically shower or bath in the mornings or evenings, and don’t really require hot (as in 50C) water during the day. Most people are too lazy to switch the geyser off while they are out of the house, or don’t have a timer switch built into their geysers.
3. In places like Cape Town, you have so much sun available that could heat up the water or provide electricity using solar energy that the use of electricity from the grid is a complete of waste.

In an attempt to make our home more environmentally friendly, we started looking at how to save energy and how to become completely independent from the grid one day. Apart from minimizing waste by recycling and using a compost, and running all electrical power and light circuits in our house via a Clipsal computer optimized system, we now have 3 solar panels that provide heated water.

Depending on the light intensity provided by the sun, water gets pumped through into the roof where solar collectors heat up water and then pump back into the Geyser. The whole system is controlled by a Geyser Wise Thermostat where I can set minimum temperature of water required over 4 different zones, that can be programmed on a timer. The thermostat automatically cools down water in the very hot summer if usage is little, in order to avoid overheating of the panels (that can get up to 80-90 Celsius easily). In case that the solar energy is not sufficient, the geyser will switch automatically to normal mode using electricity from the grid.

The only drawback that I have found at the moment is that 2×200 liter geysers take quiet some time to re-heat, once cooled down e.g. over night and I am not sure if the every morning re-heating process during winter is energy efficient compared to a ‘constant on’ mode. I will soon find out from my kW consumption bill .

The system with 3 panels, 2 controllers was procured from Germany through South African provider Solar Zone and setup by One Solar who did a great job during the 3 day installation.