Best Battery Size for a 3–4 Bed Home (UK Guide for 2026)

If you’ve got a 3–4 bedroom house and you’re adding battery storage to solar (or planning to), the “best” battery size usually comes down to one thing:

How many kWh you want to cover from late afternoon through the night.

Most 3–4 bed homes land in a sweet spot where the battery is big enough to soak up spare solar and run the house in the evening, but not so big that you’ve paid for capacity you rarely fill.

Battery unit installed in a residential garage, showing compact design and wiring

The quick answer: what size battery for a 3–4 bed home?

For most UK 3–4 bed households:

• 5 kWh – works if electricity use is low/moderate and you’re home in the day a lot

• 8–10 kWh – the most common “best fit” for typical 3–4 bed usage (especially if you’re out in the day)

• 12–15 kWh – better if you’ve got high usage, frequent evening loads, an EV, or you want more “whole-home feel” into the night

Some UK guidance aimed at homeowners suggests ~5kWh for an average 3-bed household, with bigger batteries where usage is higher.

A simple way to size your battery in 3 minutes

Step 1: Find your daily electricity use

Look at your bill: annual kWh ÷ 365 = daily kWh.

Typical ranges (very rough):

• 3 bed: ~8–12 kWh/day

• 4 bed: ~10–16 kWh/day

Step 2: Estimate your “evening + overnight” use

Most families use 50–70% of daily electricity outside peak solar hours (unless you’re home all day).

So:

• If you use 12 kWh/day, evening/overnight might be 7 kWh (about 60%).

Step 3: Choose usable battery capacity

Batteries aren’t always 100% usable. Many are ~90% usable (depends on model/settings).

Battery size ≈ (Evening/overnight kWh) ÷ 0.9

Example:Evening/overnight 7 kWh ÷ 0.9 ≈ 7.8 kWh → pick an 8 kWh battery.

Real-world “best size” examples (3–4 bed)

Example A: Typical 3-bed family, out in the day

• Daily use: ~10–12 kWh

• Wants to run house in evening + night

• Best fit: 8–10 kWh

Example B: 4-bed home, lots of cooking/laundry evenings

• Daily use: ~14–16 kWh

• Heavy evening loads

• Best fit: 10–12 kWh

Example C: 3–4 bed with EV (charged mostly at night)

• Daily use jumps and becomes “peaky”

• Best fit: 12–15 kWh (or a battery that can be expanded later)

Don’t forget the other “size”: battery power (kW), not just capacity (kWh)

Capacity (kWh) is how much energy you store.Power (kW) is how fast you can use it.

For a 3–4 bed home, you generally want enough power to handle:

• kettle / oven / hob bursts

• dishwasher + TV + lighting

• (optionally) immersion heater or EV charging integration

If your battery has low power output, you might still pull from the grid during spikes even if the battery is “full”.

Solar export limits & DNO rules can affect your design

A lot of homes end up with export-limited systems (especially when PV + battery is combined). As a reference point, SP Energy Networks notes generation connections over 3.68kW (16A) per phase fall under G99, and export limitation can be part of the process.

This doesn’t mean “you can’t have a bigger system”—it just means the install needs to be designed and notified/applied correctly.

Will a bigger battery always save more money?

Not always.

A battery that’s too big can:

• sit partially unused for long periods

• take longer to pay back

A battery that’s too small can:

• fill early and start exporting (missing the chance to use that energy later)

• still leave you buying evening electricity from the grid

The best battery is the one you can regularly fill with cheap/solar electricity and regularly empty in the expensive hours.

Can you earn money exporting with a battery + solar?

Yes. Under the Smart Export Guarantee (SEG) you can get paid for exported electricity, but you’ll need the right eligibility and metering.

Ofgem’s SEG overview confirms payments are calculated using export meter readings and you must meet eligibility criteria. Government guidance also notes you typically need a meter capable of half-hourly export readings (often a smart meter). Energy Saving Trust notes suppliers may ask for proof that the technology and installer are MCS-certified (or equivalent).

VAT: battery installs are still 0% in 2026

For residential installs in Great Britain, a 0% VAT rate applies to certain energy-saving materials until 31 March 2027 (then it reverts to 5%). That helps keep solar + battery packages more affordable right now.

Recommended battery sizes (simple shortlist)

If you just want a sensible shortlist for a 3–4 bed home:

• 8 kWh – best all-rounder for many households

• 10 kWh – great if you’re out in the day or want more evening coverage

• 12–15 kWh – best if you have high usage, an EV, or future electrification plans

FAQ

Is 5kWh enough for a 3–4 bed home?Sometimes—mainly for lower usage homes or where you’re home in the day and using solar directly. Otherwise, it can feel a bit tight in winter.

Should I size for summer or winter?Size for shoulder months + winter evenings. In summer you’ll often export more anyway.

Can I start smaller and expand later?Often yes (depends on battery brand/model). Expandable systems are a smart way to avoid overspending on day one.