Solar Thermal Energy (STE) – In recent years, much attention has been given to the benefits of generating electricity from solar panels, and the advantages to be gained from renewable electric power sources. However, the power of the sun can also be harnessed in a more straightforward, and sometimes more efficient way, to provide energy directly for heating buildings, and for a commercial or domestic water supply. As energy prices inevitably increase, an Solar Thermal Energy installation will make increasing sense for many homes and businesses in the UK.
Image: Markel Redondo by (CC BY-NC-ND 2.0)
How Solar Thermal Energy Works
The principle is simple. STE is harvested using a panel to absorb the sun’s rays, which are used to warm a fluid, or, in some cases, air. The fluid can simply be water, or, in areas at risk of freezing temperatures, a glycol mixture similar to that used in car radiators. The warmed water is circulated, sometimes passively but usually by a controller, and generally through a heat exchanger. It can then be used as part of a heating or hot water system, or in more sophisticated applications, as part of a power generation system.
How Efficient is STE?
The materials used for solar panels have been extensively researched and developed in recent years. As a result, even in cold or cloudy weather, enough heat can be absorbed through the panels to produce a useful effect. The system may be able to pay for itself in a comparatively short period of time.
How Safe is STE?
Solar Thermal Energy installations present few risks to the user, but lightning protection, surge protection, and earthing in particular, must be considered.
Lightning Protection for STE Systems
Like any metallic equipment in an exposed position, a STE array needs lightning protection. There may be an additional hazard from induced surge currents if, for example, there are power cables nearby. In this case, the surge protection is needed even when a direct lightning strike does not occur. In either case, the lightning or surge protection will be effective only if the earthing is adequate.
What Kind of Lightning Protection and Earthing is Necessary?
If the building on which the STE array is being installed already has its own lightning protection, it may simply be necessary to ensure that the Solar Thermal Energy system is linked to it, and that the earthing is of sufficient quality. (In every king of surge protection, good earthing is crucial.) It is also possible to install lightning and surge protection specifically for the STE system, which may make sense if, for example, it is being fitted at a distance from the building.
Installing a Safe STE System
A good solar energy engineer will ensure that lightning and surge protection, and the necessary earthing, are part of the initial installation. On very tall buildings or in particularly exposed locations, where lightning strikes are common or where overhead power cables pose additional risks, the advice of a specialist may be necessary.
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