Frequently asked questions
Q: We are a family of four and currently have a 150 litre geyser at home. We would like to invest in a solar water heating system. Would a 150 litre solar water heater save us money?
A: No, definitely not! A 150 litre solar system is far too small to serve your requirements. With solar water heating, volume is everything, as you require a large volume of solar heated water to carry you through to the next morning. Too small a volume equals higher electrical input and less savings. The heating element would then have to make up the extra hot water that is required. With solar water heating, ‘bigger is always better.’ An average house should not go smaller than a 300 litre solar water heating system.
Q: We live in an area where we have quite a few cloudy days. Is it worth my while to have a solar system installed?
A Even in cloudy conditions your solar heater will absorb heat. Obviously not the same as on a clear day, but certainly enough to make a sizable contribution to you water heating energy requirements.
Q: What temperature can I expect out of my solar water heating system?
A: We have designed our household units to reach approximately 50 – 55 degrees Centigrade. Any temperature above 65 – 70 degrees allows extremely hot water to come out the taps which can then be a dangerous situation in any hotel, home, bush lodge etc. Also, the higher the temperature, the greater the losses, as your solar system then becomes less efficient. An interesting point to note is that the hottest water a man can shower in is approximately 41 – 42 degrees Centigrade and a woman, 43 – 44 degrees Centigrade.
Q: What happens when it rains for a few days? Will I have hot water?
A: Yes you will have hot water. Firstly, if you have the correctly sized system installed in your home, there will be enough solar heated water for your family to use over a 24 hour period and then there will still be a carry-over of hot water for the next day. The solar storage cylinder comes complete with an electrical element and thermostat, so that when the weather is bad, the heating element, which is controlled by the thermostat, will top up the water temperature and you can still enjoy a hot shower.
Q: I would like a solar system for the hotel that I have recently bought. I have had quite a few quotes thus far and they all mention evacuated tube panels. I have been told that this is a new technology in the design of solar systems. I had flat plate panels installed in the solar system at my last hotel. What type of solar panels do you suggest for my hotel down the south coast?
A: The best panel for sunny South African conditions is the flat plate solar collector (panel). It is a hardy panel that has been fitted with armour plated glass and is efficient in sustaining the temperatures you require. Evacuated glass tube panels are not suitable and can reach very high temperatures up to boiling point, which is dangerously hot.
Q: How long will the solar heated water stay hot in the solar geyser?
A: A standard geyser has 25% less insulation than a solar geyser and this extra thick protection against heat loss, allows the solar heated water to only lose a few degrees overnight.
Q: I live in a frost area and have heard that solar panels in my area have popped during winter. We do have warm, sunny days in summer but I am concerned about installing a solar system due to the possible problem with the solar panels. Does this happen to all solar systems?
A: If the solar system is not designed correctly, frost can destroy a solar water heater. In frost areas we use an indirect system . This circulates anti-freeze through the solar panels which then stops any freeze damage.
Q: I am seriously thinking about going off the grid. Will a solar heater meet my daily hot water needs and what happens when it rains, as I will no longer be able to use an electrical element as back-up?
A: When thinking about going off the grid, the main thing to remember is that you MUST have sufficient stored volume. You can never have too much hot water storage. The more you have, the longer it lasts. However it is always advisable to have an alternative heat source like a gas geyser. This can help if you experience a long and extended period of bad weather.
Q: We are building a bush lodge and are thinking of installing both baths and showers. Will this be compatible to solar water heating systems?
A: If it is at all possible avoid installing baths at your Lodge, as the clients consume more than three times the amount of hot water than the clients who shower If you operate at a high pressure, then more hot water is consumed and therefore more energy is wasted. So the simple answer is to install showers only, with the lowest possible pressure. Do not think that pressure is the sole contribution to a good shower. We have found that the right shower rose, and this is generally one of the cheaper one’s you can buy, works exceedingly well with low pressure and you can enjoy a really good shower.
Some interesting observations: 100kPa Operating pressure delivers hot water at 11 litres per minute and a 400 kPa operating pressure delivers 26 litres per minute! Please be advised that not all mixers require high pressure and that there are mixer fittings that can operate happily at 100 kPa.