Did you know- The humble household hot water cylinder not only provides you with all your hot water needs, but it can also act as a thermal home battery, storing excess energy in the form of hot water, as well as supporting the grid during times of lower demand and higher input.
Hot Water Cylinders
A standard 150 litre hot water cylinder installed today in the UK can hold ~7kWh with a range of anywhere between 90 litres (4.2kWh) and 300 litres (14kWh).
HWA members have information labels on their products called ‘Stored Energy Labels’. It will look like this:
How a connected cylinder works
The Cylinder capacity is used to provide the hot water needs of the household. The connected cylinder works by having the ability to delay any re-heating requirement to times when there is a surplus of electricity in the grid, electricity that could otherwise be wasted.
Why would the Electricity Grid want excess energy?
From time to time the electricity grid has excess electricity generated through its network. It needs to use this energy or it will be wasted. Some energy companies even pay the customer for using this surplus electricity.
This will become more common with renewable electricity like wind turbines and solar. It needs to use this energy otherwise it will be wasted.
The Thermal solution
With over 10 million hot domestic hot water tanks installed, the UK has 70GWh of untapped energy storage potential. Some energy companies will even pay customers for that excess capacity.
Replacing an old hot water cylinder with a modern, well-insulated one, with smart controls, provides an opportunity to use low cost or even negatively priced electricity alongside the existing heating equipment. They also offer: ease of control, enhanced system boiler efficiency, and future retrofit options for heat-pumps or hydrogen-ready gas boilers.
It’s not just the electricity grid that can benefit from energy storage technology, such as hot water stores.
By combining a solar PV installation with a hot water cylinder homeowners can divert any excess energy generated by the Solar PV system to an immersion heater. This, in turn, heats the hot water cylinder, which may ordinarily be fuelled by a boiler, for use later on. Utilising excess energy n this way will save significantly on gas bills.
Hot water storage cylinders offer great potential to help accommodate more renewable energy sources into the UK’s generation infrastructure as well as supporting the grid by offering excess storage capacity.
Driving to improve standards within the domestic hot water industry