Battery

Would a battery earn its place?

See how much energy a battery could realistically move, what that might save, and whether paying for more capacity genuinely improves the result.

No sales pitch. If a battery makes little financial difference, we'll say so.

Annual household electricity use

Electricity used at home each year

kWh

Home by Numbers assumption. If you already have solar, use your home's total electricity consumption from your solar or inverter app — not only the electricity bought from the grid.

How would you use the battery?

There's no solar estimate saved yet, so there's no surplus solar to store. Add solar to this model. You can still model cheap-rate grid charging below.

Choose at least one way of using the battery to see a complete result.

Tell us about the battery

Usable rated capacity

kWh

Use the capacity shown on your quote or battery app, before any backup reserve you choose to keep.

Backup reserve

This part stays available for outages or emergencies and is not used for everyday savings.

Capacity available for everyday use: 9.0 kWh

Installed battery cost — optional

Enter the battery portion of the quote, including installation. Do not include the solar-panel cost unless the quote cannot be separated.

When does your home use electricity?

Two homes using the same electricity each year can get very different battery results. When that electricity is used matters.

00:00 — 1.5% of a typical day
01:00 — 1.2% of a typical day
02:00 — 1.0% of a typical day
03:00 — 1.0% of a typical day
04:00 — 1.2% of a typical day
05:00 — 2.0% of a typical day
06:00 — 4.5% of a typical day
07:00 — 7.0% of a typical day
08:00 — 6.0% of a typical day
09:00 — 4.0% of a typical day
10:00 — 3.2% of a typical day
11:00 — 3.0% of a typical day
12:00 — 3.2% of a typical day
13:00 — 3.0% of a typical day
14:00 — 2.8% of a typical day
15:00 — 3.2% of a typical day
16:00 — 5.5% of a typical day
17:00 — 8.5% of a typical day
18:00 — 10.0% of a typical day
19:00 — 9.0% of a typical day
20:00 — 7.0% of a typical day
21:00 — 5.5% of a typical day
22:00 — 3.8% of a typical day
23:00 — 2.5% of a typical day

An estimated shape for a typical day, not measured smart-meter data.

How do you pay for electricity?

Electricity rate

p/kWh

Home by Numbers assumption.

Your home figures are saved in this browser. When you request a solar estimate, your postcode is sent to Postcodes.io to locate the approximate area, and the resulting coordinates and solar assumptions are sent securely to PVGIS. The battery model may request hourly PVGIS solar data using the same approximate location and solar-system assumptions already used by the Solar page. Battery details and results are saved only in this browser. We don't ask for contact details or use your postcode for sales.

This removes only the battery settings and their hourly solar cache saved in this browser. The saved battery configuration used on the Tariffs page goes with it. My Energy, Solar, EV and Heating are untouched.

So what?

Choose at least one way of using the battery above to see whether it's worth it.

Once you pick how the battery would be used, this panel explains what the saving (or cost) actually means.

What you could do next

Based on your result, these are the numbers worth checking next. You stay in control — no sales calls from us.

Add a solar estimate
Without a solar estimate saved, this page can only model cheap-rate grid charging, not stored surplus solar.
Open the solar calculator
Try a different capacity
Bigger batteries don't always earn their extra cost — the size comparison below shows where the extra saving per kWh starts to shrink.
Understand the numbers behind your result
Read the plain-English Battery Guide for capacity, usable capacity, losses, reserve and simple payback.
Read the Battery Guide

Battery questions people ask

How are battery savings worked out?: We simulate your household's electricity costs twice, once without a battery and once with it, using the same solar generation, tariff rates and usage pattern in both cases. The saving is simply the difference between the two, after accounting for round-trip efficiency losses.
What's a typical payback period for a home battery?: It depends entirely on the installed cost you enter and the annual saving this calculator works out for your situation — there isn't a single typical figure. Simple payback here just divides installed cost by annual saving, and ignores financing, warranty and future price changes.
Can a battery pay for itself without solar?: Yes, if your tariff has a meaningful gap between a cheap overnight rate and your normal rate, a battery can be charged cheaply and used later to avoid paying the higher rate. Whether that gap is big enough to be worthwhile after efficiency losses is exactly what the cheap-rate charging option here models.
How does cheap-rate charging change the result?: Charging from a cheap overnight rate only helps if that rate, inflated by round-trip losses, is still cheaper than the rate you'd otherwise pay. If the gap is too small, the calculator will flag that grid charging isn't worthwhile under your current tariff.
What size battery should I consider?: There's no single right size — it depends on your usable surplus solar, your evening usage, and how much you're willing to pay per kWh of capacity. The capacity comparison table on this page shows how the annual saving changes step by step as capacity increases, so you can see where extra capacity stops adding much.

Based on your result, these numbers are worth checking next

Your saved figures will come with you.