By the end of 2025, DESNZ had recorded about 5,437 solar PV installations across Basingstoke and Deane, with a combined capacity of 80.17 MW. That count covers every size of installation, from a terrace roof in South Ham to a solar farm, so it is not a count of homes. But for the owners of the rooftop systems in that count, the question now is not whether to have solar but whether to add a battery to the panels they already have.
This guide is for them. It covers what an existing Basingstoke array actually produces across the year, the two ways a battery is connected to it, what SSEN needs to know and what the retrofit route costs compared with fitting both at once. For the town-specific picture of battery storage in Basingstoke, including the local network data, see our main page.
What the 5,437 figure does and does not say
DESNZ publishes the count by local authority, and its own notes say a large number of 2025 installations could not yet be assigned to an area, so the Basingstoke and Deane figure is likely to rise when the data are revised. The 80.17 MW total is also no guide to a typical home system, because large ground-mounted schemes sit in the same column. The borough’s planning committee, for instance, considered a 23 MW solar farm application at Strattons Farm, Kingsclere, in October 2025, with officers recommending approval. One project of that size would outweigh thousands of roofs.
What the count does tell you is that solar is well established across the borough, and that any of those arrays fitted without a battery can usually take one later. Those are the homes this guide is about.
Your array in a Basingstoke June and December
PVGIS 5.3, the European Commission’s solar calculator, estimates that a 4 kWp array facing due south at 35° in Basingstoke produces about 4,023 kWh a year. The months are very uneven: about 488 kWh in June, 487 kWh in July, 157 kWh in January and 136 kWh in December. On our arithmetic, that is roughly 16.3 kWh a day in June and 4.4 kWh a day in December. For scale, Ofgem’s typical domestic consumption figure is 2,500 kWh a year, or about 6.8 kWh a day.
So in a Basingstoke summer a south-facing array makes more than an average household uses in a day, much of it while nobody is home. In December the house uses almost all of it as it is made. A retrofit battery mostly catches the summer surplus and moves it to the evening, which is why it is sized to your evening use rather than to winter.
Two ways to connect a battery to an existing array
The first is AC coupling. The battery comes with its own inverter and connects on the household side of your existing solar inverter. The array is left as it is, which suits a system whose inverter is fairly new and working well. The second is to replace the existing inverter with a hybrid unit that runs both the panels and the battery. That can make sense where the original inverter is older or nearing the end of its warranty, since inverters typically carry shorter warranties than panels.
Which route is right for a Basingstoke house depends on the inverter label, the array’s layout and where there is room for the battery. The borough’s housing helps here: the EPC register puts the stock at roughly 30% detached and 28% semi-detached, so in a good share of homes a garage or utility room is worth looking at first. Mid-terraces, about 22% of the stock, often have no side access, which can make the battery’s position the deciding factor.
The SSEN paperwork
Basingstoke is in SSEN’s Southern Electric Power Distribution licence area, about 27 km from the nearest neighbouring network. Under the Energy Networks Association’s G98 rule, generation up to 16 A per phase (3.68 kW) is notified before commissioning or no later than 28 days after it. Anything larger needs a G99 application approved before the work starts, and a 4 kW inverter, at 17.39 A, is just over the line. A battery’s inverter counts as generation, so an existing array plus a new battery can take the whole installation over the G98 threshold. Designers handle that with a G99 application or by limiting what the system can export. SSEN aims to answer fast-track applications within 10 working days, and your installer submits them.
What the retrofit route costs
The Energy Saving Trust puts a home battery at anywhere from £1,500 to £10,000, with a 5 kWh system around £4,600, and says a typical home system might be 10 kWh. It also says fitting storage at the same time as panels costs less than a separate visit later. That is the honest catch for an existing Basingstoke array: you pay for a second installation visit that a combined job would have avoided. The battery itself carries 0% VAT until 31 March 2027 whether it is fitted with panels or on its own, then 5% from 1 April 2027. Our guide to how long solar batteries last covers the warranty side, and the Trust gives a typical lifespan of about 10 to 12 years.
What to have ready before a quote
Four things make a retrofit survey in Basingstoke quicker and more accurate: the make and model of your current inverter, your MCS certificate, a few months of import and export meter readings, and a rough idea of where a battery could go. With those, a designer can say which coupling route fits and whether the paperwork is G98 or G99. Our page on solar panels in Basingstoke covers the roof side, including the borough’s 40-plus conservation areas, and our Hampshire solar guide takes the wider county view.
Sources: DESNZ, Renewable electricity by local authority 2014 to 2025 (published 29 September 2026); PVGIS 5.3 (European Commission Joint Research Centre), PVGIS-SARAH3 2005–2023, 4 kWp, 35°, due south, 14% losses, run 15 October 2026; Ofgem, Typical Domestic Consumption Values (from 1 July 2026) and Smart Export Guarantee; Energy Saving Trust, Battery storage (updated 19 August 2026); HMRC VAT Notice 708/6; Energy Networks Association EREC G98 Issue 2 (10 March 2025); SSEN, distributor information and Who we are; NESO GB DNO licence-area boundaries; Proper Toasty analysis of GOV.UK EPC-register data for Basingstoke and Deane; Basingstoke and Deane Development Control Committee report, 8 October 2025 (24/00852/FUL).