52 RCI 0514

RCI May 2014

RENEWABLE ENERGY Solar thermal warms the way Martin Wadsworth, managing director of Discrete Heat discusses the opportunities for energy efficient domestic hot water Above and below: Discrete Heat’s Therma Twin system combines solar PV and solar thermal technology, and it is a self-contained heating system which provides up to 70% of domestic Solar thermal technology offers an effective, energy efficient and reliable way of supplying hot water to a property. When considering installing a solar thermal system the location, availability of space and hot water requirements need to be considered to ensure the most efficient solution is found. Solar thermal panels come in two types; flat-plate and evacuated-tubes. Flatplate panels usually comprise a thin sheet of metal that is positioned below a sheet of glass and acts as an absorber. These panels are ideal for new builds or roof renovations as they can often be integrated into the roof due to their naturally flat design. Evacuated-tube panels have glass tubes containing freeze proof fluid placed within a vacuum with thin strips of formed metal that act as absorbers. The vacuum reduces conduction losses giving the evacuated tube panels a higher heat transfer and therefore increased energy efficiency than that of the flat-plate panels, making them a good option for limited space as they can be mounted in any orientation. However, the tubes are more fragile and broken ones are expensive to replace while the flat-plate systems are durable enough to withstand being stood on. The solar panels are only one element of the system with a pump needed to circulate the heating fluid and a thermal store or hot water cylinder to hold the heated water until it is required. The integration with the existing hot water system depends on its compatibility, as it could drastically reduce the benefits of investing in solar thermal if it is an old, inefficient system, and so it is recommended that the backup hot water system is updated to maximise energy savings. Financial benefits to households are further contributed to by solar thermal qualifying for 052 MAY 2014 RCIMAG.COM both domestic and non-domestic RHI schemes. This means that solar thermal users will receive a minimum payment for each kilowatt hour of renewable heat that their installation is deemed to generate, decided upon by the Microgeneration Certification Scheme (MCS) estimates. The current rate for solar thermal domestic RHI payment is 19.2 p/kWh, and payments can be backdated up to 15 July 2009. Energy and heating specialists Discrete Heat has combined solar PV and solar thermal technology in the ThermaTwin solar panel that is a selfcontained heating system providing up to 70% of domestic hot water in an average year. The design cleverly encompasses a small solar PV panel to generate the electricity required to run the pumps and controls, therefore allowing the entire system to be run ‘off-grid’. As energy prices continuously rise, solar power offers a cost effective alternative to traditional hot water systems and ThermaTwin’s cost-free running further boosts savings for homeowners, while being Solar Key Marked makes it eligible for domestic RHI, Green Deal and SEAI (Ireland) grants. As with other solar thermal systems, ThermaTwin absorbs UV rays that in turn heat the water tubes within the panels, providing a hot water supply to the house. The robust, twin-walled polycarbonate window ensures durability while the lightweight construction keeps the total panel under 30kg therefore keeping the loading to the roof structure to a minimum. ThermaTwin has a very simple and reliable method of fixing to the roof, with minimal disturbance to the slates, tiles or stone covering. ThermaTwin can provide full training to existing qualified roofers or plumbers, and can provide an MCS certified installation to enable the homeowner to claim any Government Grants such as RHI or Green Deal. The system is very low maintenance as it does not use glycol or anti-freeze that normally require annual level checks, because the patented system of flexible tubes are ‘freeze tolerant’ enabling water to be supplied directly from the property’s hot water cylinder ThermaTwin is easily installed into homes running a non-pressurised system and header tank as no heat exchanger is required (although versions are available suitable for fitting onto existing pressurised systems). Heat energy is generated during the day and is most effective when there is full sunshine, but ThermaTwin will continue to contribute to the hot water throughout the year, even on cold days. www.discreteheat.co.uk hot water in an average year “The robust, twin-walled polycarbonate window ensures durability while the lightweight construction keeps the total panel under 30kg therefore keeping the loading to the roof structure to a minimum”


RCI May 2014
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