Solar Water Heating
What is it?
Solar water heating systems are designed to capture the heat of the sun and use it to directly heat water.
How does it work?
Solar water heating systems consist of solar panels or collectors, which are fitted to the roof at an angle of between 10o and 60o. These panels are highly absorbent, and draw heat from the sun. (The panels operate at their best when they are positioned south facing and free of shade). This heat is transferred to a heat transfer fluid e.g. cold water, which is circulated between the panels and a water tank. The water runs through the heating system – either actively (with the use of a pump) or passively using gravity.
The system operates in association with a conventional water heating process, such as a gas or electric immersion heater. This tops up the heat from the panels and provides hot water and space heating in the winter.
In the summer months, solar water heating can provide almost all of the hot water requirements of a typical household, and on average, this system could supply around 50% of a household’s annual hot water requirements.
Who is it suitable for?
Solar water heating can be used to heat water and/or provide space heating in domestic, commercial, agricultural and industrial premises. It is currently used mainly in households to supply hot water and in leisure facilities to heat swimming pools. However, it is increasingly being used in multi-occupancy premises (e.g. hotels) and office buildings. This technology does not require year-round sun to operate effectively and is therefore applicable for properties in the Northwest of England.
The primary barrier to uptake is economic, and there are long pay-back times. However, costs are expected to decrease as public awareness increases and a mass market is created.
The benefits
- Reduced dependency on non-renewable fossil fuels
- Reduced carbon dioxide (CO2) emissions and associated climate change impacts
- Reduced emissions of harmful gases such as sulphur dioxide (SO2), nitrogen oxides (NO x ) and particulates
- Once installed the energy is free
- Low maintenance, with a long lifespan (20-30years)
- A visible statement of commitment to the environment
- Planning permission for installation is not normally needed
- It is a mature and proven technology in the UK, and there are already 50,000 systems in operation in the UK
- The sun’s energy can be harnessed on cloudy days
For more information see:
Centre for Alternative Technology (www.cat.org.uk)
National Energy Foundation (www.nef.org.uk/actonco2/renewableenergy.htm)
Energy Saving Trust (www.est.org.uk)