5kWh Home Battery Storage: Cost, Output and What It Covers
A 5kWh battery is the entry point to home storage. What it covers, what it costs, and why the output figure matters more here than the capacity.
- Around 4.5 kWh usable
- 8-10 solar panels
- Independent advice
A 5kWh home battery suits smaller households with a modest solar array, typically around 8 to 10 panels, and starts at roughly £1,100 for the hardware. At this size the output figure matters more than the capacity: on an ordinary socket you get around 800 W, which covers lights and the fridge but not cooking. On a dedicated circuit the same unit delivers two to three times that.
How much battery storage do you actually need?
Three figures decide almost everything: how much electricity your household uses in a year, how much surplus solar power you send back to the grid, and how much of that you actually use after sunset. If you have a smart meter, the first two are usually in your energy supplier’s app. Without one, your latest annual statement lists both.
Annual consumption
Divide it by 365 to get your average day. At 3,500 kWh a year that is roughly 9.6 kWh per day.
Exported solar energy
This is the surplus a battery could have stored. Divide the annual figure by 365 for a daily average.
Evening demand
How much you use after sunset decides how much of that stored energy you actually get back out.
The smallest of those three numbers sets the useful ceiling. There is no point storing 8 kWh of surplus if you only use 4 kWh after sunset, and no point buying capacity your panels never fill. Our guide to battery capacity works through the method in full, or run your figures through the configurator below for a capacity range and an estimate of what you would save.
What does 5kWh of battery storage cover in a real home?
Nominal capacity and usable capacity are not the same thing. Most lithium iron phosphate batteries release 90 to 95% of their nominal capacity, so a 5kWh battery gives you roughly 4.5 kWh in daily use. The table below shows what that buys you.
| Appliance | Typical use | Share of 4.5 kWh usable |
|---|---|---|
| Fridge-freezer, 24 hours | 1.0-1.5 kWh | About 28% |
| Lighting, router and standby, one evening | 0.5 kWh | About 11% |
| Cooking on induction, one meal | 0.5-0.8 kWh | About 14% |
| Washing machine, 40 °C cycle | 0.6-0.9 kWh | About 17% |
| Dishwasher, eco cycle | 0.8-1.1 kWh | About 21% |
| TV and laptop, four hours | 0.3 kWh | About 7% |
| Electric oven, one hour | 1.5-2.0 kWh | About 39% |
| Heat pump, winter day | 6-12 kWh | Exceeds capacity |
| Charging an electric car, full | 50-80 kWh | Exceeds capacity |
Energy is only half the story, though. Several of the appliances above draw more power at once than a socket-connected battery can supply, so the battery covers part of the load and the grid covers the rest. The next section is the one that decides whether a 5kWh system does what you want.
800 W or 3 kW: the figure that decides everything
Modular batteries of this size are typically capped at around 800 W of discharge when they run from an ordinary earthed socket. The cap is there so the battery cannot overload a circuit it shares with other appliances, and it has nothing to do with how much the battery holds. Connected to a dedicated circuit by a qualified electrician, the same unit commonly delivers two to three kilowatts, depending on the model.
| Ordinary socket | Dedicated circuit | |
|---|---|---|
| Discharge power | About 800 W | Typically 2-3 kW |
| Covers lights, fridge, router, TV | Yes | Yes |
| Covers a washing machine cycle | Partly | Yes |
| Covers kettle, oven or hob | No | Mostly |
| Time to empty 4.5 kWh | About 6 hours | Under 2 hours |
| Installation | Plug it in | Electrician, notifiable work |
Nothing breaks at 800 W. The battery supplies what it can and the grid tops up the rest, so you simply buy more peak electricity than you were expecting to. For a small household whose evening is lights, a fridge and a television, 800 W genuinely covers most of it. Add an electric oven to the picture and it does not.
Current wiring rules also expect anything capable of feeding power into your home to sit on a circuit of its own, and the government has a safety study under way into socket-connected storage. If you are buying now, plan for a dedicated circuit.
How much does a 5kWh battery cost?
Around £1,100 to £1,400 for the hardware: the base unit with its electronics, one or two expansion modules and the meter that lets it follow your consumption. Add £250 to £500 for an electrician to run a dedicated circuit, more if the battery sits a long way from the consumer unit or you are in London or the South East.
| Capacity | Hardware | Dedicated circuit | Grid connection |
|---|---|---|---|
| 5 kWh (this page) | £1,100 – £1,400 | £250 – £500 | Connect and notify |
| 10 kWh | £2,000 – £2,500 | £250 – £500 | Connect and notify |
| 15 kWh | £2,900 – £3,600 | £250 – £500 | Connect and notify |
| 20 kWh | £3,800 – £4,700 | £250 – £500 | Connect and notify |
| 25 kWh | £4,700 – £5,800 | £250 – £500 | Prior approval |
| 30 kWh | £5,500 – £6,900 | £250 – £500 | Prior approval |
Note what the circuit column does across the whole ladder: it barely moves. That is why it weighs most heavily here, at the smallest size. Paying £400 to wire in 5kWh adds a third to the bill; paying the same to wire in 30kWh adds a rounding error. If you expect to grow, the circuit is work you only do once.
Payback depends far more on your electricity contract than on the purchase price. A household on a time-of-use tariff that charges cheaply overnight and discharges through the evening peak recovers the investment considerably faster than one on a flat tariff with a generous export rate.
Is a 5kWh home battery right for you?
Pros
- Your annual electricity use is below around 3,500 kWh
- Your evening load is lights, a fridge, a television and the odd appliance
- You have up to around 8 to 10 solar panels
- You do not charge an electric car at home, or you charge it elsewhere
- You want to start small and add modules later on the same base unit
- You have a time-of-use tariff and want to shift a few hours of consumption
Cons
- You use more than 3,500 kWh a year
- You cook on electricity and want the battery to carry it
- You have a heat pump or electric water heating
- You charge an electric car at home, even occasionally
- You have more than ten panels and export a lot in summer
- The house is empty by day and nearly all consumption is after sunset
Our take
At this size the platform matters more than the capacity. Pick a base unit that takes modules you can still buy in two years, and get the dedicated circuit done at the same time. Both are far harder to undo than the number of kilowatt-hours you start with.
Suitable for smaller homes with a few solar panels
A 5kWh battery works particularly well with a smaller solar array of around 3,000 W, roughly eight to ten panels. It stores the extra solar power your home does not use during the day and makes it available in the evening, when electricity use is usually higher. That directly reduces the amount you send back to the grid.
A practical rule of thumb is 1 to 1.5 kWh of storage per 1 kWp of installed solar capacity. Above ten panels the midday surplus in summer regularly exceeds what a 5kWh battery can absorb, so part of your generation is exported anyway. Expect a clear seasonal difference too: the battery cycles fully most days in summer, but may only charge partly in winter, which is exactly why sizing on peak summer production alone leads to an oversized system.
A 5kWh battery without solar panels
A home battery is worth having with no solar panels at all. On a time-of-use tariff the battery charges when electricity is cheap, usually overnight, and supplies the house through the expensive evening hours. At this size the sum is simple: one cycle a day, roughly 4.5 kWh shifted, multiplied by the gap between your cheap and peak rates.
5kWh is well matched to this, because a system charging at up to 3 kW refills the whole stack inside a couple of hours of a cheap overnight window with room to spare. Larger stacks do not always manage that. Our guide to sizing a battery without solar panels covers what decides the benefit and what to check before switching tariff.
Is 5kWh enough for backup power?
A 5kWh battery holds enough energy for a long run of essential loads, but what it can run at once is set by the backup output, which is a separate specification from both capacity and normal discharge power. On modular systems the backup socket commonly starts around 1 kW and rises to about 3 kW once at least one expansion module is fitted.
So check three figures rather than one: capacity in kWh, normal discharge power in kW, and backup output in kW. A battery with plenty of stored energy behind a 1 kW backup socket still cannot start a washing machine, however full it is. And note that a backup socket powers what you plug into it, not your house circuits; whole-house backup is a feature of conventional installed systems.
| Connected load | Power | Runtime on 4.5 kWh |
|---|---|---|
| Fridge, lights, router, phone charging | 150-250 W | 18-30 hours |
| The above plus TV and a laptop | 350-450 W | 10-13 hours |
| Add a small heater or kettle in bursts | 1,000-1,500 W | 3-4 hours |
| Electric oven or induction hob | 2,000-3,000 W | Under 2 hours, if supported at all |
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Can you charge an electric car from a 5kWh battery?
Charging an electric car is very different from powering a fridge or a few lights. Car batteries are many times larger than 5kWh and need high charging power. A 5kWh home battery can add a small amount of driving range, but it is not suitable for fully charging a car.
In numbers: a typical electric car holds 50 to 80 kWh, and a home charger delivers 3.7 to 11 kW. A fully charged 5kWh battery would cover roughly 12 to 20 miles of range, and a charger alone draws more power than the battery can supply, so the grid would be doing most of the work regardless. Households that charge at home are better served by a cheap overnight tariff than by trying to route the car through a small battery.
What to check before you buy a 5kWh battery
Capacity is only one specification. These are the figures that decide whether a system performs well in your home.
| Specification | Why it matters | Typical at 5 kWh |
|---|---|---|
| Usable capacity | What you actually get out of the battery each cycle | 4.3-4.8 kWh |
| Discharge power | Decides how much of your evening load the battery can carry | 800 W on a socket, typically 2-3 kW on a dedicated circuit |
| Charge power | Decides whether you can refill inside a cheap tariff window | Up to about 3 kW |
| Backup output | What you can run during a power cut, separate from the figures above | 1 kW, up to about 3 kW with a module fitted |
| Cycle life and warranty | The real measure of lifespan, more than the number of years | 10 years or 6,000-8,000 cycles |
| Expandability | How far the same base unit grows before you need a second one | Often around 20 kWh, varies by brand |
| Metering | How the battery sees your consumption | P1 or CT meter at the consumer unit |
| Protection rating | Required for outdoor placement | IP65 for outdoor use |
Our capacity guide explains how the connection type sets your output and what your network operator needs, which at this size is a straightforward notification after the work is done.
5kWh or 10kWh?
This is the most common decision homeowners face. The honest test is not which battery is better, but whether you have enough surplus solar and enough evening consumption to fill the extra space every day.
| 5 kWh | 10 kWh | |
|---|---|---|
| Usable capacity | About 4.5 kWh | About 9.0 kWh |
| Hardware | £1,100 – £1,400 | £2,000 – £2,500 |
| Discharge power | Same | Same |
| Suits annual use of | Up to about 3,500 kWh | Up to about 6,000 kWh |
| Solar array | 8-10 panels | 10-20 panels |
Two things worth noticing. Doubling the capacity does not quite double the price, because the base unit’s electronics are paid for once. And the output figure does not change at all: a 10kWh system discharges no faster than a 5kWh one, it just keeps going for longer. If your problem is that the battery runs out before morning, the extra capacity solves it. If your problem is that it cannot cover the oven, it does not.
If you are hesitating and the system is modular, starting at 5kWh is a defensible choice: you can add a module once you see your real usage data, instead of paying now for capacity you might never fill.
Frequently asked questions
How long does a 5kWh home battery last?
That depends on how much electricity you use and on the output. Running lights, a fridge and a router, a full battery lasts well over a day. Discharging at its full rate on a dedicated circuit it empties in under two hours, and at 800 W from a socket in around six. As a rule, 4.5 kWh usable divided by the connected load in kilowatts gives the runtime in hours.
How much does a 5kWh battery cost?
Around £1,100 to £1,400 for the hardware, plus £250 to £500 for an electrician to run a dedicated circuit. A conventional installation built around a hybrid inverter is a different product and costs several thousand pounds more for the same storage.
Why is a plug-in battery limited to 800 W?
Because an ordinary socket shares a circuit with other appliances, and a battery feeding power onto that circuit alongside them could overload it. Moving it to a dedicated circuit removes the shared load, which is why output typically rises to two or three kilowatts there.
Do I need an electrician for a 5kWh battery?
For a dedicated circuit, yes, and that is the configuration to plan for. A new circuit is notifiable work, so it has to be done by a registered electrician or signed off by Building Control. The installer also handles the notification to your network operator, which at this size happens after the work rather than before.
Can you expand a 5kWh home battery later?
On a modular system, yes. The base unit takes further expansion modules up to a stated maximum, often somewhere around 20 kWh in total. Check whether new modules have to match the age, capacity or firmware of the existing ones, and whether the model you choose will still be supplied in a few years.
What warranty do you get with a 5kWh battery?
The warranty differs by brand and model. Many manufacturers offer around 10 years or a set number of charging cycles, commonly 6,000 to 8,000. The cycle count is the more meaningful figure, because a battery in daily use completes a little under one cycle per day.
Is 5kWh a lot for a home battery?
No, it sits at the lower end of the market. Ceilings vary by brand, but a single modular unit tends to reach somewhere around 20 kWh and three units in parallel roughly 60 kWh. At 5kWh you are buying a base unit with a module or two, aimed at households with modest consumption.
How many solar panels do you need for a 5kWh battery?
Roughly eight to ten panels, or about 3,000 W. With more panels than that, a 5kWh battery often cannot absorb the full midday surplus in summer and part of your generation is exported to the grid.
Can a 5kWh battery power a heat pump?
Not through a winter day. A heat pump typically uses 6 to 12 kWh in cold weather, which is more than a 5kWh battery holds, and its continuous draw sits above what a socket-connected system can supply. A household with a heat pump is usually better served by 10kWh or more on a dedicated circuit.