What is solar hot water?
Solar water heating systems, or solar thermal systems, use energy from the sun to warm water for storage in a hot water cylinder or thermal store. Because the amount of available solar energy varies throughout the year, a solar water heating system won’t provide 100% of the hot water required throughout the year. A conventional boiler or immersion heater is normally used to make up the difference.
Larger solar hot water arrays can also be arranged to provide some contribution to heating your home. However, the amount of heat provided is generally very small (less than 10% of the home’s heating requirement), so it is not usually considered worthwhile.
Most solar hot water systems are just designed to provide the hot water you use for bathing, showering and hot taps.
How do solar hot water heating systems work?
Solar water heating systems use panels or tubes, called solar collectors, to gather solar energy. The solar collectors convert the infra-red portion of visible light into heat. They are filled with a mix of water and glycol. This fluid is pumped round a circuit, which passes through the hot water cylinder.
There are two types of solar water heating collectors:
- Evacuated tubes – a bank of glass tubes mounted on the roof tiles.
- Flat plate collectors – fixed on the roof tiles or integrated into the roof.
Benefits of solar water heating
Hot water throughout the year
The system works all year round, though you’ll need to heat the water further with a boiler or immersion heater, especially during the winter months. In the summer, it should provide around 90% of your hot water requirements, dropping to around 25% in the winter.
Reduced energy bills
Sunlight is free, so your hot water costs will be reduced.
Lower carbon footprint
Solar water heating is a renewable heating system and can reduce your carbon dioxide emissions.
Is solar water heating right for your home?
To tell if solar water heating is right for you, there are a few key questions to consider:
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Do you have a sunny place to put solar panels?
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Do you have space for a larger hot water cylinder?
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Is your current boiler compatible with solar water heating?
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Will you need planning permission?
Costs and savings
Costs
The cost of installing a typical solar water heating system is around £3,000 to £5,000. Costs will depend on whether you choose evacuated tube or flat plate collectors, as well as the size of the system.
Savings
Solar water heating systems will normally be designed to provide roughly half your hot water requirement. The saving will vary throughout the year, with systems providing nearly all your hot water in the summer, but less during the winter months.