If you’re investing in solar panels or expanding your solar energy system, one critical question arises: What size solar battery do I need? With rising electricity costs and the UK’s net-zero goals, solar batteries are increasingly popular for those looking to maximise energy independence and efficiency.
Our expert guide is tailored for UK homeowners, landlords, and commercial property owners who want to reduce their reliance on the National Grid, cut bills, and make smart energy investments.
Let’s dive into the essential details to ensure your solar battery system is the right fit, financially, practically, and environmentally.
What Size Solar Battery Do I Need?
The ideal solar battery size depends on:
- Your daily electricity usage (measured in kWh)
- Solar panel output: Considering how many solar panels you can install on your roof will directly impact your solar output.
- Your goal: backup only, full independence, or energy savings
- Property type: residential vs commercial
Typical usage examples
- Homeowners: Average daily electricity use is 8–10kWh. A 5-10kWh battery is usually sufficient.
- Landlords (HMOs): Higher occupancy means higher demand. 10-15kWh is often ideal.
- Commercial properties: Depending on business type, you may need 20kWh to over 100kWh.
How to Calculate the Solar Battery Size You Need
- Calculate average daily consumption
- Check your electricity bill (look for kWh/day).
- Estimate usable solar generation
- Consider UK sunlight hours (average 2.5-4 hours/day). To get a foundational understanding of your potential solar generation, it’s useful to consider what appliances can be powered even by a smaller setup, such as what you can power with a 100 watt solar panel.
- Decide on your storage target
- Do you want to store 100% of your excess, or just enough for evenings?
Example:
- Daily use: 10kWh
- Solar generation: 6kWh/day
- Desired storage: 80% of excess = ~5kWh battery needed
Navigating solar battery sizing can be complex to ensure you maximize your energy independence and savings. If you’re a homeowner in Newcastle or the North East looking to incorporate battery storage into your solar system, Future Heat can provide expert guidance.
Request a free, no-obligation quote for your solar battery system today, and our MCS-accredited team will help you determine the ideal battery size for your specific energy needs and solar generation.
What Are the Most Common Solar Battery Sizes in the UK?
| Battery Size (kWh) | Suitable For | Estimated Cost (Installed) |
|---|---|---|
| 3–5kWh | Small flats or bungalows | £2,000 – £4,000 |
| 5–10kWh | Medium-sized homes | £4,000 – £6,000 |
| 10–15kWh | Large homes or HMOs | £6,000 – £9,000 |
| 20kWh+ | Businesses & commercial use | £10,000+ |
Note: Prices vary based on brand, installation complexity, and inverter compatibility.
What Size Solar Battery Do Commercial Properties Need?
The size of the solar battery a commercial property needs depends on the scale of energy usage, the type of business operations, and energy efficiency goals.
Commercial properties often consume significantly more electricity than residential properties, especially if they run equipment, lighting, IT infrastructure, or refrigeration systems throughout the day and night.
Key factors for commercial battery sizing
- Daily electricity consumption: Businesses using over 50kWh/day may benefit from batteries starting at 30kWh.
- Peak usage patterns: If a business has high demand in evenings or early mornings, larger capacity batteries ensure adequate supply.
- Solar PV array size: Larger solar arrays can generate more excess energy to store, justifying higher capacity batteries.
- Desired autonomy: Businesses seeking energy resilience or off-grid backup may require battery banks exceeding 100kWh.
Typical commercial battery sizes
- Small businesses (retail, offices): 20–40kWh
- Warehouses, manufacturing sites: 50–100kWh+
- Data centres, large facilities: Custom setups starting at 100kWh and scaling into MWh
Benefits for commercial users
- Reduce peak tariffs and demand charges
- Increase grid independence during power outages
- Meet corporate ESG targets and sustainability mandates
Battery systems for commercial use often integrate with energy management systems (EMS) for real-time optimisation and remote monitoring. MCS-certified commercial installers can perform detailed audits to size your system accurately based on your electricity profile and business goals.
How Long Does a Solar Battery Last?
Most solar batteries last 10–15 years with a warranty of 7–10 years.
Key metrics to consider
- Cycle life: Number of charge/discharge cycles
- Depth of discharge (DoD): Higher DoD means more usable capacity
- Round-trip efficiency: Typically 85–90%
Example: A battery with 6,000 cycles and used once per day could last over 16 years.
Are Solar Batteries Worth It in the UK?
For homeowners
- Reduce energy bills by up to 70%
- Increase EPC rating for home resale
- Eligible for 0% VAT on battery storage until March 2027 (VAT notice)
For landlords
- Improve tenant satisfaction and reduce void periods
- Boost EPC compliance to meet the minimum C rating
For businesses
- Lower operational costs
- Enhance ESG (Environmental, Social & Governance) credentials
What Are the Best Solar Batteries in the UK Market?
- Tesla Powerwall 2: 13.5kWh, high efficiency, seamless backup
- LG Chem RESU: Modular sizes, reliable brand
- Growatt ARK: Cost-effective, scalable
Choosing the right installer
Use MCS-certified installers for quality assurance. Check Ofgem and RECC directories for accredited providers.
How Much Can I Save with a Solar Battery?
- A 5kWh battery can reduce bills by £250-£400/year
- Larger systems (10-15kWh) can offer £700+ in annual savings
Smart Export Guarantee (SEG)
Unused stored energy can be sold back to the grid. Rates vary by supplier. Compare options via the Ofgem SEG register.
How Do Solar Batteries Affect Property Value?
- Homes with solar batteries can command higher resale values
- Landlords benefit from improved EPC ratings, which are mandatory for letting
- Commercial sites with renewables attract green-conscious tenants and investors
Frequently Asked Questions (FAQs)
Yes, you can connect multiple solar batteries in parallel to increase your total storage capacity. This is particularly useful for commercial properties or large households with high energy usage. Be sure to work with an MCS-certified installer to ensure the system is correctly configured and safe.
Not necessarily. Oversizing a battery without matching it to your actual usage or solar generation can lead to underutilisation and longer payback periods. A well-sized battery, based on your energy profile, delivers better ROI than simply choosing the largest available unit.
While oversizing provides more flexibility and backup power, it may lead to higher upfront costs and a longer return on investment. Undersizing can result in missed storage opportunities. A professional energy audit can help you strike the right balance.
If your battery is too small, it may fill up quickly, forcing excess energy back to the grid rather than storing it. You may also find yourself drawing from the grid during periods of high usage, reducing the benefits of your solar system.
Yes. Many modern battery systems are modular and scalable, allowing you to add more capacity over time. However, compatibility and space planning should be considered upfront during initial installation to avoid costly retrofits.
Our Verdict
Selecting the right solar battery size is all about understanding your energy usage patterns, solar generation potential, and long-term energy goals. Whether you’re reducing bills at home, enhancing property value as a landlord, or cutting operational costs as a business, battery storage can offer both financial and environmental rewards.
For most UK homes, systems between 5kWh and 15kWh are usually the best fit. Commercial properties, with their broader energy demands, will benefit from tailored solutions, often starting from 20kWh and scaling upwards.
A well-sized solar battery isn’t just about capacity—it’s about return on investment, sustainability, and future readiness.
Myles Robinson is a seasoned expert in the boiler and home improvement industry, with over a decade of experience. He is deeply committed to environmental sustainability, actively promoting energy-efficient heating solutions to help households reduce their carbon footprint. By combining industry expertise with a dedication to environmental responsibility, Myles continues to lead efforts in transforming home heating practices towards a more sustainable future.
