In brief
A battery stores daytime solar for the evening; it adds no extra generation. It suits households that are out by day, busy in the evening or heating with electricity, and helps least in midwinter, when there is little surplus to store. Its inverter counts towards the G98 limit, and installed batteries carry 0% VAT until 31 March 2027.
What a battery does, and what it does not
A home battery stores electricity when the panels are making more than the house needs and releases it later, usually in the evening. It is a timing device. It does not raise the yearly output of the roof, and a little energy is lost each time it charges and discharges. What it changes is the split between electricity used at home and electricity sent to the grid, covered in detail on export and self-use.
Because a unit used at home normally replaces a dearer unit bought from the supplier, moving surplus from midday to the evening can add value. How much depends on the size of that surplus, the household’s evening use and the tariffs involved. This guide does not put a figure on it, because each of those varies from home to home.
The surplus changes with the seasons
For a 4 kWp array facing south at 35°, PVGIS 5.3 suggests an average of about 15.6 kWh a day in Jun near Crewe, falling to 3.9 kWh a day in Dec. In summer, a household that is out during the day may export much of that output, which gives a battery plenty to store. In midwinter, the house can use everything the panels make as it is made, and a battery may barely fill.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| kWh a day | 4.1 | 7.2 | 10.6 | 14.7 | 15.5 | 15.6 | 15.0 | 13.5 | 11.7 | 7.8 | 5.3 | 3.9 |
That seasonal swing is the main reason to ask for a season-by-season estimate rather than a yearly one. A battery that fills most days from April to September and rarely in December is behaving normally; the question is whether the months when it is useful justify its cost for your household.
When storage tends to help
- Empty by day, busy by evening. A household out at work or school produces a midday surplus and an evening peak, the pattern a battery is built for.
- Electric heating and hot water. Homes heated by electricity use more power overall, and in spring and autumn a battery can carry daytime surplus into the evening. In Crewe Central, 16.6% of households heat with electricity alone, against 5.6% across the borough; electric heating in Crewe explains how solar fits.
- Two-rate tariffs. On some tariffs a battery can also charge from the grid at a cheaper time of night and run the house on stored power later.
- A larger array. The bigger the summer surplus, the more a battery has to work with.
When it helps less
A household at home through the day, already running its appliances in daylight, may use most of its output directly and leave little for a battery. A small array on a narrow terraced roof may rarely produce much surplus at all; terraced houses covers those roofs. And where space is short, as in many flats and smaller houses, finding a suitable spot for a battery can be the deciding factor. Flats raise further questions about whose supply the battery would serve, set out on flats and solar.
The grid step: G98 or G99
Every system connected to the network is notified to, or approved by, the network operator, which you can identify through the ENA postcode search. Under G98, a system up to 16 A per phase (3.68 kW where the supply is single-phase) can be connected and then notified within 28 days. The battery’s inverter counts towards that rating as well as the solar inverter’s.
Adding a battery can easily take a home system over that limit, and then a G99 application has to be approved before connection. The operator may approve it with an export limit, programmed into the equipment, that caps what can flow to the grid at any moment. Ask each firm which route its design needs and who will handle the paperwork; grid connection in Crewe explains the steps.
Fitting now or adding later
A battery can be installed with the panels or added afterwards. Some solar inverters, often called hybrid inverters, are designed to take a battery directly, which can make a later addition simpler. Alternatively, a battery with its own inverter can be connected alongside an existing system. If you think you may want storage in future, say so at the survey, so the firm can leave room in the design and explain the options. Prices for systems with and without storage vary widely, and solar costs in Crewe explains what the government’s price data does and does not include.
Batteries and power cuts
Many people assume a battery keeps the lights on in a power cut. Usually it does not. A grid-connected system is designed to shut down when the grid fails, so that it cannot send power into cables that engineers may be working on. Some batteries can supply a backup circuit, or the whole house, during a cut, but only if the system is designed and wired for it, which adds cost and equipment. If backup matters to you, say so at the start and ask exactly which circuits would stay on and for how long.
Where it will go
A battery needs a suitable place: dry, within the temperature range the maker specifies, and with space around it for ventilation and maintenance. Lofts, garages, utility rooms and outside walls are all used, depending on the product. Ask where the firm proposes to put it and why, how it will be fixed, and what the maker’s instructions say about the location. Do not accept a position simply because it is the only space left.
Switch Together and batteries
Cheshire East Council’s Switch Together scheme is a group buy covering Cheshire and Warrington, formerly known as Solar Together. The council says households that already had panels could register for a battery. It reports 3.22 MWh of battery storage delivered through the scheme. Registrations for the 2026 round ran from 3 August 2026 to 25 September 2026, so it is not open now; the council’s page is the place to watch for another round. More on the scheme is on grants and schemes.
VAT
Under HMRC’s VAT Notice 708/6, installed solar panels and batteries carry 0% VAT until 31 March 2027, after which the rate is 5%. The rate is built into the price, so check which one each quote uses.
Questions to put to any firm quoting for a battery
- How often will the battery fill in each season, based on this household’s use?
- Does it change the grid route from G98 to G99, and who applies?
- Where will it go, and does that position meet the maker’s requirements?
- What warranty does it carry, and does the warranty depend on how it is used?
- Can it charge from the grid at night, and does the household’s tariff make that worthwhile?
Checks on the firm itself are on choosing an installer. To ask about storage for a particular home, use the question form.