Evacuated Tube Solar Collectors
Norfolk Solar Power uses top of the range solar panels collectors that are suitable for both domestic and commercial applications.
The efficiency of these units is such that just one solar collector is adequate for an average household (3-4 people). The system is modular, so you can add more collectors if required. It also conforms to British Standards BS EN 12975.
For commercial applications, a survey is required to assess hot water requirements. A single panel is sufficient for a 200 litre cylinder.
Free solar heating is potentially available to almost every house in the UK, indeed, every house really ought to have one already. With an overall efficiency of almost 80%, Solar Water Heating is a cost effective way of reducing your fuel bills, and more importantly, lowering your CO2 emissions to help combat global warming.
How Evacuated Tube Solar Collectors work
The vacuum tube solar panel has been around for over 5 years and has proved to be both reliable and dependable. The vacuum tubes consist of a double wall glass tube (made from strong borosilicate glass i.e. pyrex) with a space in the centre which contains the heat pipe.
The sun's radiation is absorbed by the selective coating on the inner glass surface, but is prevented from re-radiating out by the silvered innermost lining which has been optimised for infra-red radiation. This acts similarly to a one-way mirror.
This is very efficient; of the sun light's energy hitting the tube's surface, 93% is absorbed, whereas only 7% is lost through reflection and re-emission. The presence of the vacuum wall prevents any losses by conduction or convection - just like a thermos flask. Because of this, the system will work even in very low temperatures, unlike traditional flat plate collectors.
The heat transferred to the tip of the heat pipe is in turn transferred to a copper manifold in which water circulates to heat the domestic hot water tank. If a tube is placed in direct sunlight on a summer day, the tip temperature can reach 250°C - so the system easily heats domestic hot water cylinders to 60°C even in cooler weather.
The manifold is heavily insulated with a 2" thickness of pre-formed rockwool to keep the heat in. Unlike flat plates, these headers are so well insulated that they should not require antifreeze in normal operation - the temperature of the header is unlikely to fall below 10°C even in very cold weather. The more advanced solar controllers include a low-temperature facility - should the temperature of the collector fall below a defined level, the pump will operate to allow the the water at the bottom of the tank to heat the collector slightly. In normal conditions, this would never be necessary, but it acts as a good safety margin.
We are a DTI registered company 2142904 (Low Carbon Buildings Programme/BRE accredited installer). Grants are available on application. See www.lowcarbonbuildings.org.uk for more details.
