If you’re looking to lower your carbon footprint and save on those ever-increasing energy bills, then a great option is too install a solar hot water system. By heating your own water you will not only save money, but also reduce your carbon dioxide (CO2) emissions. Although solar thermal systems are reasonably expensive (between £2,500 and £5,000), they are a well-developed technology that is eligible for a grant and they will provide about third of a property’s hot water supply.
This technology is primarily aimed at the domestic user, with the most common method of water heating coming from a rooftop-mounted solar thermal collector. Note: before you get too excited about the possibility of showering with water heated using only the sun; there are a couple of issues to point out to potential buyers. Although any reputable supplier of this equipment should survey your property first, you should bear in mind that:
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You will need a hot water storage tank – if you live in a small property and only use a combi boiler, then this is not for you. This storage tank – which should be supplied as part of the package – will double as your domestic hot water cylinder, one of which you probably already have inside the airing cupboard.
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Ideally a solar hot water collector will be fitted on an angled roof that faces south. This is not to say that if your roof faces east or west that you can’t install one, it’s just that in this case the collector would only get it’s maximum amount of sunlight in the morning (east) or afternoon (west), dramatically reducing it effectiveness.
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DIY kits are available, but you need to be competent, especially when it comes to plumbing.
How does it work?
In simple terms, solar radiation (sunshine to you and me) is absorbed into the collector, which is typically 3–5 square metres in area. As the water contained within the system becomes hot, a pump transfers this hot water to a heat exchanger within the storage tank, which then in turn, heats up the water in the tank ready for use – easy.
There are essentially two types of collector that are used in Northern Europe: the flat plate collector, which looks like a more traditional solar panel, and the evacuated tube collector, which looks like a large chrome radiator.
The Savings
The average financial savings that can be made are now around £100* per year. The emissions savings that can be achieved are between 260kg and 580kg of CO2 per year, if replacing a gas or electric heater respectively [1]. Additionally, it’s worth considering the payback time. Let’s say that you buy system and it costs you £2500, and that you also get a grant of £400. At a saving of £100 per year, you will have made your money back in around twenty years. I know that sounds like a long time, but consider this: A decent system should last you longer than that, – most appear to be made to last 25 years or more as they are relatively simple with very few moving parts. Also remember that energy prices will continue to rise, and as they do the savings will also increase. So a payback time of considerably less should be achievable. Once you paid yourself back, you will be enjoying truly free hot water, not to mention doing your bit save the planet and help stop climate change.
Remember
To maximise the efficiency of the system, also consider these tips:
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Buy a washing machine or dishwasher that runs off the hot water feed, saving the need for the machine to heat its own water.
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Time your hot water usage to coincide with the times that the tank is full of hot water, with the added chance of the sun heating a replacement tank afterwards. For example, on a sunny day if you put a load in the washing machine have a shower and then wash the dishes all after lunch, the sun will have heated your water in the morning and then willl have plenty of time to heat up more for the evening. Lovely.
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Avoid the ‘rebound effect’ i.e. “this water’s heated by the sun, so I can forget about conserving it ”.
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Look for a system that uses a small solar PV (electric supply) panel to run the pump, saving even more energy. If not possible try, to add one on later, they’re not that expensive.
To look more into the grants that are available, visit the low carbon building programme [2]. At the time of writing, the grant available for a solar thermal system is £400. There are some other top-up grants around, often form local councils, but with the current climate (pardon the pun!) they may soon disappear. Check out the grants database at Energy Saving Trust [3].
*With an average house bill now around £1000 per year and considering 30% of a household energy bill is on water heating. Solar hot water can deliver a third of that equating to an average saving of around £100 per year. Some suppliers claim that they it can deliver up to 70% of hot water demand, but if you work on just a third, then everything else is a bonus
[1] DECC (2010)http://www.lowcarbonbuildings.org.uk/Microgeneration-Technologies/Solar-thermal-hot-water Accessed 13/05/2010
[2] www.lowcarbonbuildings.org.uk
[3] www.energysavingtrust.org.uk
Guardian Online (2008) Household fuel bills could rise 40%www.guardian.co.uk/business/2008/jun/24/oilandgascompanies.gas. Accessed 13/05/2010
