Solar Thermal Water Heating Panel
Water can be heated by pumping it through a panel designed to trap solar radiation and convert it into heat in a collector in close thermal contact with the water. Thus, the heat is transferred to the water. The water is normally pumped through the panel from the bottom of a water tank and returned to the top of the same tank. Stratification keeps the hot water returned from the panel from mixing fully with the cold, heavier water below it, so we don’t need to be able to heat the whole tank to the desired temperature before we can obtain hot water.
This technique for obtaining free hot water is used routinely in Mediterranean latitudes where the sun is so strong, and the skies are so clear, that “thermo- syphoning” can be used. No pump is needed, and this is the simplest possible way to collect free hot water. However, in more northern latitudes and especially where the sun can suddenly appear and then disappear as clouds pass over, we need to be able to start and stop the flow of water through the panel as the trapped solar energy follows the fluctuation of the incident solar energy. We need a pump and a controller.
Our Controller and Panel
Tirna Electronics Ltd is currently developing a sophisticated, microprocessor based controller, which controls up to 3 hot water tanks automatically or under user control. The controller can be used with a smart home system called Home Assistant, which can be used through a web browser or smart device app, remotely and securely. There is no anticipated release date for the Home Assistant version. However we believe there is a need for a simpler system, that doesn’t require Home Assistant. The simple controller can be installed and maintained by the user with nothing more than a cheap, widely available voltmeter.
If the user is DIY minded, they should also be able to make and install their own panel, with the help of a plumber if necessary. If you want to build your own controller you are free to do so but it would be easier to register your interest with us, and tell us what you want to do with it (we may be able to advise on some points).
If you would prefer to buy the simple controller and/or the panel, both will be available in limited quantities by the second quarter of 2020. When more than 20 people have registered an interest in the controller, we will have them made.
Whether you make your own controller and panel or buy them from us, we recommend the book by Lee Rose, “Solar hot water – choosing, fitting and using a system”. ISBN: 978-0-9549171-9-7, Published in 2012 by Low-Impact Living Initiative, Redfield Community, Winslow, Bucks. This excellent book contains 265 pages of informative, and essential information.