The answer first
A battery stores daytime surplus for the evening. It suits homes that export much of their summer output and helps least in midwinter, when there is little surplus to store. Its inverter counts towards the G98 limit of 16 A per phase, so adding one can mean a G99 application first. Installed batteries carry 0% VAT until 31 March 2027.
What a battery changes
During the day a solar roof often makes more than the house is using, and the surplus is exported. A battery catches some of that surplus and releases it later, when the panels have stopped and the house would otherwise buy from the grid. Some energy is lost in charging and discharging, so slightly less comes out than went in. A battery adds nothing to what the roof generates; it changes when the electricity is used, and therefore how much is exported.
That makes it a question of timing. A household that uses most of its electricity in the evening, and exports most of its daytime output, has the most to shift. One that is busy during the day already uses much of its output as it is made, and a battery would sit partly idle. The month-by-month split between use and export is on export and self-use.
The winter gap
Output near Nantwich is strongly seasonal. PVGIS 5.3 models a 4 kWp south-facing system at 35° averaging about 15.8 kWh a day through June, falling to roughly 4.0 kWh a day through December. In midwinter most of that small amount is used in the house as it is made, so there is little or nothing left over to store. A battery charged only from solar therefore does most of its work between spring and autumn, and much less from November to February. The unit also draws a little power itself to stay ready, which matters most in the months when it has least to store.
Oil-heated village houses
In the village wards around Nantwich, oil and LPG heat a large share of homes; in Audlem 45.7% of households use oil alone. For those houses electricity demand is mostly lights, cooking, appliances and the boiler’s own pump and controls. On a long summer day the roof can make far more than that, and the evening demand is modest enough that a battery may cover a good part of it for much of the year.
A hot-water diverter competes for the same surplus. It sends spare power to the immersion element in the cylinder, which suits a house where the boiler would otherwise fire for hot water alone. A battery and a diverter can work together, with one filling before the other, but the order needs setting up deliberately. The heating side of these houses is covered on off-gas villages.
Electric-heated flats
In Nantwich North and West 11.7% of households heat with electricity alone, many of them in flats. Their heaviest demand falls on winter evenings and nights, which is when solar output is lowest. A battery charged from panels will help with ordinary evening use in the brighter months, but it cannot carry winter heating. Some households instead use a battery to store cheaper off-peak electricity from the grid, which depends on the tariff rather than on solar at all. In a flat there is also the question of where a battery could go and who must agree to it, since communal areas and the outside of the block belong to the building owner; see flats and solar.
Where the battery goes
Home batteries are usually fixed in a garage, a utility room, a loft or on an outside wall, following the maker’s instructions on temperature, ventilation and clearances. Escape routes, such as a hall or stairway, are generally avoided. Keep the space around the unit clear, and make sure everyone in the house knows where its isolators are. In an older timber-framed house the fixing wall and the cable route need thought, and in a listed building, fixing equipment to the fabric or running new cables can itself need consent; read timber-framed homes before choosing a spot.
The G98 and G99 step
Adding a battery can change how the system connects to the network. Under the G98 route, inverters whose combined rating stays within 16 A on each phase (on a single-phase supply that is roughly 3.68 kW) may go live first and be notified to the network operator within 28 days. Both the solar inverter and the battery’s are included in that sum. Should the total exceed it, the system falls under G99, which means applying to the operator and waiting for approval before connection. Approval can come with conditions, such as a limit on export. Find the operator with the Energy Networks Association postcode search, and read grid connection for the detail.
Adding storage to existing panels
A battery can be added to a solar system already on the roof. Some designs connect it through its own inverter on the house wiring; others replace the solar inverter with a hybrid unit that runs both. Either way, ask how the change affects the warranties on the existing equipment, whether the network operator needs a new notification or application, and whether the original MCS paperwork needs updating.
Living with a battery
A battery is controlled by settings as much as by hardware. Most let the owner choose when it charges and discharges, how much charge to hold in reserve for a power cut where back-up is fitted, and whether it may charge from the grid at night. The defaults suit an average household, which may not be yours, so ask the firm to explain the settings at handover and to leave them written down. Software updates arrive from time to time and can change how a unit behaves. Usable capacity fades slowly over the years, which the warranty should describe. At the end of its life a battery has to be removed and recycled properly, so ask who takes it back.
Switch Together and batteries
Cheshire East’s Switch Together group-buying scheme has included batteries as well as panels, and its 2026 round also invited households that already had solar to register for a battery to be added. The council reports 3.22 MWh of battery storage across the scheme. Registration for 2026 ran from 3 August 2026 to 25 September 2026, and that window has passed. What is available instead is listed on grants and schemes.
VAT on batteries
According to HMRC’s VAT Notice 708/6, home batteries carry no VAT until the end of March 2027; the 5% rate applies to work from 1 April 2027. That covers a battery fitted with new panels and one added to an existing system. Quotes show VAT within the price, so if the work could straddle the change, ask which rate has been used.
Questions to put to the firm
- What is the usable capacity, as opposed to the headline figure, and how was the size chosen from the household’s own usage?
- What warranty applies, for how many years or cycles, and what capacity is promised at the end of it?
- Will the system keep any circuits running in a power cut, and if so, which?
- Does the combined inverter capacity stay within G98, and who handles the notification or G99 application?
- Where will the battery be fixed, and how does that location meet the maker’s instructions?
- Does the firm’s entry on the MCS register include battery storage as well as solar PV?
Every check worth making on a firm is listed on choosing an installer, and the price guide sits on solar costs. For storage at a specific address, ask a question and the reply will come by email.