Solar water heating systems use the free heat from the sun to warm hot water for domestic properties. Thermal water heaters can be combined with conventional boiler or immersion heaters (which can be used to make the water hotter or provide all the hot water when solar energy is unavailable for some reason). Sunlight remains the one, clean, unlimited energy source. It’s environmentally friendly and freely available to everyone (“free” being the operative term! No cost means limiting damage from energy company price increases). Solar radiation is one of the greatest known forms of sustainable energy and it’s available throughout the year, even on overcast days. This kind of energy can be effectively harvested by the installation of solar thermal technology.
How does it work?
Solar thermal systems transform both direct and diffuse solar radiation into heat using solar thermal collectors. This heat is then used to heat water in domestic and commercial properties alike whilst reducing carbon emissions and combating global warming. The principle is very simple: If you leave an unrolled hose pipe on the ground and leave it exposed to sunlight, the water will soon become warm. Solar thermal collectors work in very much the same way (except much more efficiently!) Solar Thermal is a clean, safe and highly effective means of utilising renewable energy from the sun to heat our water.
The ‘Science bit’
Roof or ground-mounted solar thermal collectors are connected to one coil of a two-coil cylinder, using a sealed circuit containing a special glycol/water antifreeze solution. The fluid will not only remain liquid at temperatures as low as -25ºC but also withstand the (sometimes) high temperatures of a British summer’s day. The fluid in the thermal collectors is heated by the sun’s rays then pumped through the system and into to the hot water tank. Like most alternative, renewable energy sources, you don’t have to use them in isolation and consign your combi-boiler or other hot water systems to the scrap heap. They’re perfectly compatible, so you can have the best of both worlds (while the rest of the world catches up).
Choosing the Right Solar Thermal Collector for your property
There are two types of thermal collectors used for solar water heating systems. These are: Evacuated Tube Collectors and Flat Plate Collectors
Evacuated Tube Collectors combine individual tubes set inside panels, with heat-absorbing antifreeze solution circulating through them.
Flat Plate Collectors are most easily described as plates of heat-absorbent material that are mounted in any location that gets a lot of sun. The flat plate collector absorbs the sun’s heat then transfers it to fluid flowing through the system.
For extra efficiency, Evacuated Tube Collectors usually have highly reflective, weather-proof CPC (Compound Parabolic Concentrator) reflectors on each tube. The clever design of the reflector means that both direct and diffused sunlight falls onto the absorber. This considerably improves the energy yield markedly.
Is Solar Thermal Right for My Home?
There are one or two myths concerning solar energy that we often redress at Broad Oak, such as the belief that solar panels and solar thermal systems only work during the summer, yet, this fantastic, free energy is available all year round. The other fallacy is that these systems can work only in when there is bright sunshine and thus solar thermal energy technology is not really unsuited suitable to our climate here in the UK. However, the solar thermal systems that we recommend at Broad Oak are highly-functional in any kind of light conditions (otherwise we would not recommend them). It stands to reason that they will achieve the best results on bright, cloudless and sunny days, but we can assure you that they will also perform almost as well in overcast or diffuse conditions.
Every solar thermal system we install uses one of the aforementioned heat collectors mounted on the in a south-facing direction to allow optimal levels of heat-transfer. During the summer months, the technology has the capability to heat the water to boiling point and so temperature-limiting safety features are incorporated to stop this. The system naturally heats to a lesser degree during winter, but the output from solar thermal systems can still be considerable, meaning significant, year-round savings, not just with your summer bills. A good way to look at it is that it takes the same amount of energy to raise water temperature from 1ºC to 2 ºC as from 99 ºC to 100 ºC. 1º is 1º, after all!