James Elston
Published May 26, 2025
Last Updated on May 29, 2025
As more UK homeowners and landlords embrace solar energy, one common question arises: How many storage batteries are needed to power a house? The answer depends on several factors, including your electricity usage, battery size, solar system size, and backup requirements.
Understanding the right number of solar batteries to meet your energy needs is crucial for optimising performance and return on investment.
Contents
How Many Solar Batteries Are Needed To Run A House?
The number of solar batteries required to power a house in the UK depends on:
- Daily energy consumption
- Battery capacity (measured in kWh)
- Depth of discharge (DoD)
- Backup duration (e.g. overnight, full day autonomy)
In general, the average UK home consumes between 8–12 kWh per day. A standard lithium-ion solar battery stores about 4–13 kWh of usable energy.
For full off-grid functionality, a typical household may need 2 to 3 batteries to cover daily usage, especially during winter or cloudy periods when solar production is lower.
Let’s explore a breakdown by property type:
| Property Type | Average Daily Usage (kWh) | Recommended Battery Size | No. of Batteries Needed (5kWh each) |
|---|---|---|---|
| 1-Bed Flat | 4–6 kWh | 5–10 kWh | 1–2 Batteries |
| 2-Bed Terrace House | 6–10 kWh | 10–15 kWh | 2–3 Batteries |
| 3-Bed Semi-Detached | 10–14 kWh | 15–20 kWh | 3–4 Batteries |
| 4-Bed Detached | 14–20+ kWh | 20–30+ kWh | 4–6 Batteries |
| Small Commercial Unit | 25–40 kWh | 30–50 kWh | 6–10 Batteries |
Factors like insulation, occupancy, appliances, and EV charging can impact these figures. You can also use your electricity bill to check your average daily kWh usage and determine your ideal battery system.
Sizing Your Solar Battery Bank Correctly
Selecting the right solar battery size ensures you maximise energy storage without overspending. If you’re wondering what size you will need, it’s important to look at:
- Usable capacity (not just total kWh)
- Discharge rate
- Round-trip efficiency
- Compatibility with your solar panel system
If your home uses 12 kWh per day, and your battery has a usable storage of 5 kWh, you’ll need at least three batteries to meet your demand. How long a solar battery can power your house also depends on your energy consumption and the results of this calculation.
Backup Power: Batteries During Power Cuts
A key benefit for many homeowners is ensuring energy supply during power cuts. But do solar batteries work during a power outage? Not all systems do unless they are configured with an island mode or hybrid inverter.
If backup power is a priority, you may need extra battery storage to cover essential loads like lighting, refrigeration, and Wi-Fi over an extended period.
Consider Solar Battery Lifespan & Maintenance
Before investing, many people ask how long do solar batteries last? Most lithium-ion batteries last 10–15 years or 5,000–6,000 cycles, depending on quality and usage.
Understanding your long-term usage can help you decide if it’s best to oversize your system initially or scale later.
Additionally, it’s worth noting that solar battery costs can vary depending on brand, capacity, and installation complexity. However, a well-chosen system can significantly reduce energy bills and increase your home’s energy independence.
What If You Already Have Solar Panels?
If you’ve already gone solar, the good news is that you can add a battery to your existing solar system. This retrofit approach allows you to store excess energy instead of exporting it back to the grid.
Pairing your system with the right battery size makes your setup more self-reliant and efficient.
Get Expert Help: Request Your Free Solar Battery Quote Today
Looking to get the right number of batteries for your home or rental property?
Whether you want full backup or to cut energy bills, our team of UK solar experts will guide you through the process. We’ll calculate your energy needs, recommend the right battery size, and provide a tailored quote, no obligation, 100% free.
Request your free solar battery quote today and start your journey to energy independence.
James Elston
Boiler Expert
James Elston is the top boiler replacement and heating expert at Eco Happy. He has over 20 years of experience in the industry, focusing on Gas Safe boiler installations and offering home-heating and energy-saving solutions to homeowners across the UK. From sourcing the most energy-efficient combi boiler to providing specialist heating advice, James ensures that Eco Happy maintains the highest standards and best customer service.