With gas, electric and oil costs increasing, the provision of domestic hot water within a dwelling or business premises is getting more expensive – and that’s before you’ve considered the environmental impact of accessing fossil fuel supplies, or the fact that they will run out at some point in the future.

Solar thermal technology can help to reduce bills and reliance on non-renewable sources of energy by pre-heating water within the domestic hot water system, which means less energy is used to bring it up to the set temperature required.

The benefits of solar thermal panels are as follows:

• Solar thermal panels can be easily seen, thanks to their prominent location on the roof. Being so visible means they can provide a good ‘green advert’, which demonstrates a development’s green credentials very clearly.
• The prospect of free water heating for showers and baths is appealing to residents, since their energy bills will be reduced.

Of course, no renewable is without a drawback, so there is one limitation that should be recognised:

• On typical solar thermal installations, the heat cannot be exported, which means excess heat may be wasted – the system size therefore needs to be carefully considered. However, it can be tricky to size it accurately, since it is difficult to ascertain whether there is light/normal/heavy hot water usage before a property is occupied.

Finally, there are some other considerations that should be borne in mind:

• Flat plate solar thermal panels are less efficient than vacuum tube collectors, but they are cheaper to buy. The decision should therefore be based on the suitable roof area available (south-facing being optimal), and the angle of the panel (30° being ideal).
• Vacuum tube solar collectors are more expensive to replace if several tubes get broken, but many designs do allow the replacement of individual tubes, so it isn’t necessary to re-fit the whole solar panel.
• It’s worth considering what may happen if the property is not used for a long period during the summer. Solar thermal systems without a pump down facility, or the ability to get rid of heat, may vent the fluid if the system gets overheated. The system will therefore need refilling on return, and this must be done by a professional with specialist equipment.
• Solar thermal systems are complex, and therefore a solar photovoltaic system may be more appropriate, with higher annual energy savings and lower maintenance requirements.

For more information about solar thermal collectors, and to discuss whether they might be suitable for a particular project, please contact us. Or why not consider another type of renewable heat generation, for example, air source or ground source heat pumps?