Much has been said and propagated about saving on energy by employing solar energy to heat water. This drive should be supported and measures implemented wherever possible and practical. A wide range of solar geysers and equipment is available on the market today and everybody building a new house or any kind of building should certainly incorporate a suitable system in the planning of the building. Owners of existing buildings should also endeavor to make the change.
Let us consider a normal small household situation installing a solar water heating system. How big will the financial saving be? While it is a fact of life that we all should start saving on energy, careful investigation and calculation should be done beforehand to avoid disappointment if unrealistic expectations about savings on municipal bills do not materialize. The idea, after all, is to pay back the capital outlay of the solar system by the savings on the municipal bill in a reasonable period of time.
It is therefore necessary to analyze your municipal bill carefully to calculate over a 12 month period your average actual electricity usage, which maybe as little as 25% or less of the total bill. The total bill includes tax and services such as sewerage and refuse removal, also a fixed amount for availability of electricity which you pay – regardless whether you use it or not. Also bear in mind that freezers, lights, washing machines, tumble driers, kettles and other household appliances are not going to be affected in any way by installing a solar geyser – only the water geyser!
Calculations are easy to do. On the assumption that you can save R100 pm on your actual electricity usage and installation of a typical low-cost system of R6500, taken from your house bond, it will take you up to 7 years to get even.
Several innovative DIY plans to reduce capital outlay and interest, have seen the light, ranging from manually controlled systems to circulate water between a coiled plastic pipe on the roof to more advanced automatically controlled systems with non-return valves and temperature sensors. Although these are more affordable than the commercial available types, they still need a fair amount of capital expenditure and skill to install.
For those who are very short on finances,there is however, another very cheap possibility, depending on your willingness and ability to change your lifestyle. Is it practical to take your bath during the day, during sunlight hours? Install a black plastic water pipe in a flat coil on a flat roof surface. Reroute the geyser cold water supply into the coil and connect the outlet of the coil to the geyser inlet. Open the hot water tap during sunshine hours and your geyser will be fed with this preheated water at up to 60 degrees C. Depending on the size and length of the coiled pipe, you will have 25 to 30 liters of very hot water available for your shower.
The requirements for this DIY plan are only two connections between your existing water pipe and the coil, and 100 meters of pipe with 15 or 20mm diameter and DIY and can be done for less than R250.
Do take note of your municipal water pressure to ensure you use the correct class of pipe.
Pipe should be coiled flat on the roof. With the weight of water in the pipe, wind should not have any influence on the pipe. If the roof is not flat, the pipe should be properly secured so it cannot move under gravity.
Naturally, if you use the hot tap after sunset, this plan will not work as the coil will be cold.