The concept of using the sun to provide heat and hot water has been around for many years, but it is only in the last decade that the UK has seen a considerable increase in the deployment of solar thermal systems to provide domestic hot water for domestic and commercial purposes. Whilst the scale of this increase has not been in the same league as solar PV panels, the latest raft of financial incentives issued by the government will no doubt generate interest in the technology and result in a massive increase in uptake.
The solar thermal systems that are typically in use in the UK are of the active type; they rely on mechanical means to transport the heat away from the collector to a storage area such as a hot water cylinder. Passive solar heating, for the purposes of clarification, would be a situation where the storage location is directly heated by the sun, such as the living space of a house or building that is oriented in a way that means the suns thermal power can be made use of for direct space heating.
Solar thermal systems shouldn’t be confused with electricity generating photovoltaic panels. Their singular purpose is to capture the suns energy and use it to produce domestic hot water. Solar thermal systems can, though less practically, also contribute to space-heating.
During summer time, a solar thermal system can meet the entire requirement for domestic hot water and meet a substantial portion of it during spring and autumn. Overall, a well-designed solar thermal system consisting of good quality components could deliver up to 60% of the annual need for DHW.
How long will a Solar Thermal system last?
Solar thermal systems don’t have many moving parts at all so there’s not much to go wrong; provided the system has been installed correctly a lifetime of approx. 20-30 years can be expected. Components with working parts such as pumps, sensors etc. may need replacing at some point during this period.
How much will I save?
Because solar thermal systems work to produce domestic hot water, it is only this component of your expenditure on energy that you’ll save money on. Typically, a solar thermal system can produce up to 60% of your domestic hot water requirements, so you should see the commensurate drop in bills depending on how your hot water usage relates to your heating requirements. The difference maker is the Renewable Heat Incentive, this applies to solar thermal installations whether you’re on grid gas or not and will pay you for the hot water your system produces. Over the course of the tariff period you can expect the RHI to cover the cost of the installation, combined with the savings that will be made the prospect of installing a solar thermal system can be very attractive.