We tried to keep this as brief as possible but it still got a bit long. Use these short cut links to jump to different sections.
Active Solar    Passive Solar    Solar Thermal    Hot water   Space heating

The suns rays can be collected for use in buildings to provide energy in an active or passive manner. This is an introduction to the different technologies involved. Please note prices mentioned are exclusive of any grants that may be available.

Active Solar

Is where panels or tubes called collectors transform the suns rays into heat or electricity which is transferred from the collector and usedin a managed way within the building.

There are two types of active systems. Thermal for producing heat energy and photvoltaic for producing electrical energy. These are quite different but are often confused as the rooftop collectors for each look similar to the untrained eye. This house has both types of collector. Lower left is a solar thermal collector whilst above are ten photovoltaic panels. To find out more about this house and its solar enhancements visit www.solarious.co.uk 

Solar thermal

At present Greenshop Solar is mainly concerned with solar thermal systems. These systems are about 85% efficient at converting the suns rays intousable heat energy and since the heating requirement of a typical building in the UK is over 80% of its total annual energy use they make a bigger impact on your energy bills and carbon emission savings than photovoltaics.

Solar hot water

The first level, and most common application, of solar thermal is to heat the domestic hot water which is about 20-25% of your heat energy requirement.

Supplying around two thirds of your annual hot water demand by solar heating will typically need 2 or 3 square metres of collector and will cost between £2,500 and £4,500. Prices vary depending on whether a vacuum tube collector (as shown in the picture on the right), which is more efficient in winter, or a flat plate collector is used and whether mains pressure hot water is required, as well as the specific requirements of your building.

From March to September solar energy will provide all your hot water but will only partly heat water during the winter months when your boiler will need to be used to bring it up to temperature.

Prices include all system components from collectors to dual coil solar hot water cylinders (a cutaway example is shown in the picture on the left), pumps and system controllers. Since most homes will need to replace their current hot water cylinder, with a dual coil solar model, we advise switching to mains pressure hot water since this allows higher performance from your solar collectors and gives you a much better shower.

These systems are relatively easy to price (try our online estimator ) and to install usually taking just a couple of days for a domestic property. We can of course also provide larger solar hot water systems for multi occupancy buildings such as hotels, halls of residence, schools or public toilets.

Solar space (room) heating

The second level of solar thermal is to use the heat energy to contribute to your space heating requirement which is typically about 70% of the heat energy used.

This can be done by installing more collectors on the roof, using a larger capacity thermal store instead of a normal solar hot water cylinder.This is integrated into the heating/energy management system in the building. The solar contribution can be used most effectively with low temperature heating systems such as under floor heating. Also since a thermal store is larger than a hot water cylinder it will need to be installed in a boiler room or basement rather than your airing cupboard.

These systems cost from £6000 installed and will typically employ 6-10 square metres of collector to provide an effective contribution to space heating, which is of course mainly required in the winter months. With more collectors the system must be carefully designed to deal with excess heat generated in summer. Systems such as these are more involved to install but save larger amounts of energy and make bigger reductions in CO2 emissions.

Greenshop Solar is the sole UK distributor for some of the most advanced thermal stores available. See our website www.consolar.co.ukfor more information.

Passive Solar

Is where the suns rays pass through windows into the building and heat is stored by the floor and walls within the building and then radiates warmth later after the sun has gone. Good building design will maximise solar gain whilst managing overheating by careful use of shading and natural ventilation.

These systems rely on south facing windows with good insulation and coated glass to reflect the heat back into the building. Windows are usually shaded to allow the low winter sun into the building providing much needed heat but keeping out the summer sun to prevent the building from over heating. These principles can be best maximised in conjunction with insulation and air tightness in the design of new buildings.

This diagram shows how shading, in this case the roof overhang, is used to reduce solar gain in the hot summer months, when the sun is high, but permits lower winter sunlight to penetrate the building. The diagram, from the planning stages of a proposed building on The Green Shop site, also shows natural ventilation and daylighting features.