Independent Solar Thermal Installers

Solar water heating can help you to reduce your water-heating bills and protect the environment!

Solar energy can be used in two different ways:

• Solar Thermal systems use the sun’s energy to produce hot water
• Photovoltaic panels use the sun’s energy to generate electricity

At Llani Solar we supply and install Solar Thermal systems - to produce hot water for a wide range of domestic and commercial uses.

Households on average spend between 27% and 35% of their total energy cost on heating water. Solar panels can significantly reduce bills (producing around 60% of a households annual hot water needs) and at the same time substantially reduce carbon dioxide emissions.

How does it work?

A solar energy system needs to absorb, retain, transfer and store the Sun’s energy as efficiently as possible. 

To do this, a Solar Thermal system consists of one or more solar collectors, a pump and electronic controller, and a store (domestic hot-water cylinder). 

The controller measures the temperature of the water in the panel and compares this to the cylinder temperature. 

If the temperature of the water in the solar collector is more than 8 degrees higher than the water in the cylinder, then the controller turns on a circulating pump to transfer the heat from the collector to the hot water storage cylinder. 

There will need to be some form of frost protection in the paneland this is usually achieved using antifreeze.

What types of collector are there?

There are two basic types of collector:

• Flat Plate Collectors use an absorber plate usually covered with a transparent material such as glass and insulated behind to prevent heat losses. Heat is transferred to the water via pipes lying along the plate or through channels within the collector. They tend to be simpler and slightly cheaper form of panel. They are also more robust with less to go wrong, and in most situations they are the best choice.
• Evacuated Tube Collectors use an evacuated glass tube to enclose a slender absorber plate. Convection losses are almost eliminated by the vacuum in the tubes, making this type of collector more efficient than the flat plate. However, the total heat output is similar from each type of panel, because the tubes are fitted as part of a smaller overall panel. The smaller size makes tubes a better choice on roofs where space is limited, for example for roofs with dormer windows or Velux roof lights.

Will it work in the UK?

Modern Solar Thermal collectors do not require direct sunshine to work, and will work in overcast conditions. But to work effectively they need to face between South-west and South-east, and to slope between 35 - 45 degrees from the horizontal. In addition, the panels should not be shaded by tall buildings, trees, or chimneys.

Solar Thermal systems cannot normally contribute to space heating, as radiators tend to run at 70 degrees. Solar cannot provide these temperatures in the winter months when solar radiation is at its least powerful. However, solar panels can contribute to underfloor heating, because they use water at only 30-40 degrees, especially in well-insulated new-build projects with low heating loads.

With all Solar Thermal systems you will need a top-up heating source, for cold and grey winter days. Solar Thermal can be designed to work with all water-heating systems – gas or oil boilers, solid fuel stoves and ranges, combi boilers, electric immersions and Economy 7, and even heat pumps.  

For more information about how Solar Thermal systems work, and a very simple self-assessment chart to find out if solar water heating is right for you, please download our Solar Fact Sheet.

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