What is a thermal battery for your home?
A thermal battery stores energy as heat instead of electricity. It is charged when energy is available or cheap and releases heat for heating and hot water later.
A thermal battery is a well-insulated store, usually of hot water, that is heated by a heat pump or electricity and gives the heat back to your home hours later. Batbubble is a water-based thermal battery with its own controller.
How a thermal battery works
- Charge. A heat pump or electric heater warms the water when solar power is available or electricity is cheap.
- Store. Insulation keeps the heat in. Hot water rises, so the top of a tall tank stays hottest.
- Release. Your heating system and hot-water taps draw on the stored heat when you need it.
How much energy it holds depends on its size and on how far the water temperature can swing between full and empty. Work it out with the storage calculator.
Three ways to store heat at home
Each stores heat in a different material. All of them are sometimes called thermal or heat batteries.
| Type | Stores heat in | Typically used for | Examples |
|---|---|---|---|
| Water-based | Hot water in an insulated tank | Space heating and hot water; works directly with radiators and underfloor heating | Batbubble, buffer tanks, hot-water cylinders |
| Phase-change | A material that melts and solidifies, such as a salt | Mostly hot water in compact units | Units often sold as "heat batteries" or salt boilers |
| Solid, high-temperature | Blocks of stone, ceramic or similar heated to high temperatures | Replacing a boiler in larger homes | Boiler-replacement heat batteries |
Thermal battery, buffer tank or hot-water cylinder?
| Hot-water cylinder | Buffer tank | Thermal battery (Batbubble) | |
|---|---|---|---|
| Main job | Hot water for taps | Smooths heat pump or boiler operation | Stores heat for later use, for heating and hot water |
| Typical size | Smaller | Varies | 1,000 L or 2,000 L |
| Decides when to charge | Timer or thermostat | The heat source | Its own controller, using solar, tariffs and tank temperature (planned) |
| Use of surplus solar | With an added diverter | With an added immersion heater | Built in |
Questions about thermal batteries
Is a thermal battery the same as a hot-water cylinder?
Both store hot water. A thermal battery is larger, better insulated and controlled so that it can store heat for space heating as well as hot water, and charge when energy is cheapest.
Is a thermal battery the same as a heat battery?
The terms overlap. In the UK, "heat battery" usually means a phase-change unit. Batbubble is a water-based thermal battery.
Do I need water-based heating?
Yes. Batbubble supplies heat through radiators or underfloor heating that use hot water.
Be among the first to get Batbubble.
Batbubble is in development. Join the waiting list for development and availability updates. It is not a purchase or reservation.