The short version
General information, not advice
- Batteries store electricity for later use
- Most common with solar panels
- Can increase self-consumption
- Expensive upfront
- May benefit from time-of-use tariffs
See it step by step
A day with and without a battery
Step 1 of 6
Storage plus timing
A home battery stores electricity for later. It does not generate any. It fills up from solar panels or from the grid, often in the cheaper overnight hours, and the home draws on it instead of the grid.
Here is an example home on a time-of-use tariff with no battery. The columns show what it uses each half hour. The evening peak is where the money goes.
- The day on this tariff
- £3.10
The tariff, its rates and the home's usage are example figures.
Figures from the Switch4Good guide, Home batteries explained, checked 4 October 2026: the 85 to 95% efficiency, the sizes, the £3,000 to £8,000+ cost, the cycle life, the warranty and the lifespan are the guide's own statements, not independently checked. Tariff rates, band times, the export rate, solar output and household usage are examples. The saving is for one example day, not a year. Not to scale.
Home battery systems store electricity for later use. They are most commonly installed alongside solar panels, but can also be used with time-of-use tariffs to store cheap off-peak electricity.
As electricity pricing becomes more dynamic and renewable generation increases, home batteries are becoming a key part of flexible energy systems.
This guide explains how battery storage works, costs, payback considerations and when it may or may not make financial sense.
What a Home Battery Actually Does
A home battery stores electricity for later use. It does not generate energy — it stores surplus electricity either from:
- Solar panels
- The grid (often during cheaper overnight periods)
When your home needs electricity, the battery can discharge stored power instead of drawing from the grid.
Think of it as:
Energy storage + timing control.
Battery Capacity and Realistic Expectations
Battery capacity is measured in kWh.
Common sizes:
- 5 kWh
- 8–10 kWh
- 13–15 kWh
A 10 kWh battery could:
- Cover evening lighting, appliances and devices
- Power essential loads for several hours
It typically cannot power:
- An entire home indefinitely
- Electric heating systems for extended periods
Battery sizing should match your usage profile, not just your solar generation.
Batteries and Time-of-Use Tariffs
Batteries can charge overnight when electricity is cheaper and discharge during peak pricing.
This can reduce bills under time-of-use tariffs.
However, financial return depends on:
- Price difference between off-peak and peak
- Battery round-trip efficiency (usually 85–95%)
- Battery cycle lifespan
- Tariff stability
Arbitrage (buy low, use high) works best when price spreads are large and predictable.
Solar + Battery: Integrated Energy Systems
The most common battery use case is increasing solar self-consumption.
Without battery:
- Surplus solar exports at SEG rate
- Evening consumption comes from grid
With battery:
- Surplus solar stored
- Used in evening
- Reduced grid import
This increases solar value but increases upfront cost.
Backup Power Capabilities
Some battery systems provide backup during power cuts.
However:
- Not all systems offer full backup
- Some require additional hardware
- Backup capacity may be limited to specific circuits
If backup is important (e.g. medical equipment), confirm this capability explicitly.
Costs, Degradation and Lifespan
Battery systems often cost:
- £3,000–£8,000+ depending on size and complexity
Lithium batteries degrade gradually. Manufacturers specify:
- Cycle life (e.g. 6,000–10,000 cycles)
- Warranty period (often 10 years)
- Guaranteed minimum retained capacity
Battery replacement cost should be considered in long-term economics.
Key takeaways
- Batteries increase solar value
- Useful for time-of-use tariffs
- High upfront cost
- Financial case varies
Common questions
Will a battery eliminate my electricity bill?
No. It reduces grid dependence but rarely eliminates it entirely.
Is a battery worth it without solar?
Sometimes, especially with time-of-use tariffs, but returns depend on price spreads.
How long do home batteries last?
Typically 10–15 years, depending on usage and warranty.
Can a battery power my home during a blackout?
Some can, but not all. Check backup capability.
Do batteries require maintenance?
Minimal, but firmware updates and monitoring are important.
Is battery technology improving quickly?
Yes. Costs and performance are evolving, which can affect long-term value assumptions.
Switch energy
Compare regulated UK energy tariffs. At least 50% of eligible commission goes to your chosen cause.