Low or zero carbon solar? Solar water heating is now classified into two types of “carbon impacts”: low carbon solar or zero carbon solar. Cutting global warming and not having to use any mains electricity, even if it is derived from a “green tariff” in order to run a solar panel is becoming important to many users of solar water heating. Low carbon solar uses mains electric pumps, typically rated at 30-60 watts power consumption to circulate water, antifreeze or air between the hot cylinder and the solar panel. Low carbon solar consumes further additional electrical energy to control a small computer called a solar controller which switches this pump on or off depending on whether the panel is hotter or colder than the cylinder. The “parasitic mains electricity consumption” of conventional solar water heating negates it carbon savings by around 20% according to data in a report published by the DTI in UK.
Zero carbon solar uses either a thermosyphon or a solar electric pump to move water from the panel to the cylinder where it is stored. A thermosyphon solar water heating system relies on hot water being lighter than cold so that it floats upwards. Thermosyphon requires the hot water cylinder to be located above the solar panel. This design, which is most appropriate to flat roofs in countries where there is little chance of freezing, is uncommon in UK and Ireland. Alternatively, solar electric photovoltaic or PV) pump can therefore be used to pump water downwards when the sun shines. This uses no mains electricity and is therefore described as zero carbon solar. PV pumping is the usual approach to water pumping for zero carbon solar in UK and Ireland.
Solartwin is zero carbon solar. We do not offer mains powered pumping unless specifically instructed to do so.
Solar keymark certified
Micropower council
Renewable Energy Association
Association for Environment Conscious Building