Why battery storage works in a flat
Most battery storage content assumes you've got a detached house, a south-facing roof, and space for solar panels. If you live in a flat – or you own one – you've probably assumed this isn't for you.
It is. A home battery doesn't need solar panels. It charges from the grid overnight when electricity is cheap, then powers your flat during the day when prices are two to four times higher. That's called load shifting, and it works in any home with a consumer unit and a smart meter.
(Octopus Go)
(Octopus Go, avg.)
(every day)
Will it actually fit?
This is the first question everyone asks. Modern home batteries are compact wall-mounted units – nothing like the industrial setups you might be picturing.
Dimensions
About the size of a small boiler. Slimmer than a kitchen cupboard.
Where it goes
Utility cupboard, hallway, airing cupboard, or kitchen wall near the consumer unit.
Noise
About the same as a fridge. Place in a hallway or cupboard to keep it out of living areas.
The battery connects to your consumer unit (fuse box). In nearly all installations, a new consumer unit is needed to accommodate the battery safely – your installer handles this as part of the job.
How it works (no solar required)
Switch to a time-of-use tariff
Octopus Go gives you 9.5p/kWh overnight (00:30–05:30) vs ~33p during the day. Economy 7 also works, though with a smaller spread.
Battery charges overnight
Automatically charges from the grid during the cheap window. A 10kWh battery fills in about 3 hours. You sleep through it.
Powers your flat all day
Lights, kettle, TV, laptop, router – it all runs off stored energy at the overnight rate instead of the peak price.
How much can you save?
For a flat, 10kWh is the sweet spot. It's large enough to cover most of your daily usage, small enough to wall-mount, and the payback actually works. Here's what the numbers look like on Octopus Go.
(10kWh, inc. 0% VAT)
(Octopus Go)
(within warranty)
(~16 years daily use)
A flat using 8–12 kWh/day won't fully discharge 10kWh every day – realistically you'll use 7–8 kWh of stored energy daily. At ~24p saved per kWh (9.5p overnight vs ~33p peak), that's £1.65–1.90/day, or £600–700/year at the top end. We quote £400–550 to be conservative and account for days you're out or usage is lower.
Landlords: why this is worth doing
If you own a flat and let it out, a home battery is one of the smartest improvements you can make right now. Here's why.
For your property
- Improves EPC rating (energy efficiency)
- Adds tangible value at resale
- 0% VAT on installation until March 2027
- Capital improvement – may be deductible against capital gains
- No structural work, no external changes
- Battery warrantied for 10+ years
For your tenant
- Electricity bill drops by £400–550/year
- Set-and-forget – no effort from the tenant
- Works with any energy supplier
- Tangible benefit that aids retention
- Particularly valuable for tenants on prepayment meters
- Differentiates your property in the market
Here's the practical reality: if a tenant in a leasehold flat tries to install a battery themselves, they'll almost certainly need freeholder consent for the electrical alterations. That process can be slow, expensive, or simply refused. Landlords don't have this problem – particularly if you own the freehold. You control the property, you approve the work, and you capture the long-term value.
What about HMOs and multi-unit buildings?
If each flat has its own consumer unit and electricity meter, each can have its own battery – installed independently. For HMOs on a shared meter, a single larger battery serving the communal supply can reduce costs across the board, though the setup is more complex and you'll want an installer experienced with commercial-style configurations.
Leaseholders: what to know
If you own your flat on a lease, be upfront about the reality. Most leases require freeholder consent for any electrical alterations, and getting that consent can be unpredictable. Some freeholders will approve it quickly, others won't engage at all.
If your freeholder is responsive, the installation itself is straightforward – internal only, no structural work, half a day to complete. If they're not, you may want to raise it with your managing agent or at the next residents' meeting. The stronger the collective case, the better.
Internal battery installations generally fall under permitted development, so planning permission isn't usually an issue. The sticking point is the lease, not the law.
Choosing the right battery for a flat
Not every battery suits a flat. Here's what to prioritise when space is tight.
Go wall-mounted
Floor-standing units take up floor area you don't have. Wall-mounted options like the GivEnergy 5.2kWh, Fox ESS ECS, and Myenergi Libbi are slim enough for a hallway or cupboard.
Match the capacity to your usage
A one-bed flat typically uses 6–8 kWh/day; a two-bed uses 8–12 kWh. A 10kWh battery covers the vast majority of daily usage in either case, which is why the payback works. Smaller batteries (5kWh) are cheaper upfront but the savings are too thin to justify the install – you'd be looking at 12–14 years to break even.
Check the warranty
Look for at least 10 years. GivEnergy, Fox ESS, and Myenergi all offer this as standard, with guaranteed capacity retention of 70–80% over the warranty period.
Hybrid inverter matters
Even if you're going battery-only now, choose a system with a hybrid inverter. If solar panels become an option later – or if the next owner wants them – the inverter is already in place. The most expensive component is already done.
Frequently asked questions
Yes. Modern home batteries are roughly the size of a small boiler – around 73cm tall, 64cm wide, and 25cm deep. They wall-mount in a utility cupboard, hallway, or on any interior wall. No garage, loft, or outdoor space needed.
No. A standalone battery charges directly from the grid during cheap off-peak hours and powers your flat during expensive peak periods. No solar panels, no roof access required.
Yes – and it's a smart move. A home battery is a fixed improvement that increases the EPC rating and property value. The landlord pays for the installation, the tenant benefits from lower bills, and the property is worth more at resale. No structural work required.
If you're a leaseholder, most leases require freeholder consent for electrical alterations. This can be slow or refused. Landlords who own the freehold have no such barrier – they control the property and approve the work directly.
Yes. Since February 2024, standalone battery installations – even without solar – qualify for 0% VAT in the UK. This applies to flats and apartments and runs until 31 March 2027.
Most standard setups don't provide backup during a grid outage – they're designed to work alongside the grid. Some systems offer an optional EPS (Emergency Power Supply) feature, but this adds cost. For most flat-dwellers, the savings case alone justifies the investment.
Yes, when installed by a qualified electrician. Home batteries use lithium iron phosphate (LFP) – the safest lithium chemistry available. They need a ventilated space and shouldn't go in bedrooms or fully enclosed cupboards without airflow.
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