UK Homes That Cut Their Imports: Case Studies With Real Numbers

Every household that fits solar panels and a battery wants to know the same thing: what will I actually achieve? Not the brochure claim, but the measured result. This page collects what documented UK homes and monitored research programmes have really delivered: how much a 5kWp-class array generates, what a 10kWh battery does to self-consumption, what the systems cost, and, just as important, where the imports still come from.

The headline numbers are encouraging but honest. Adding a battery to a solar installation raises the share of its own generation a home uses from 30 to 40% to between 70 and 80%, according to guidance from Great British Energy¹. One documented household with a 5kWp-class array uses around 3,000kWh of its own output each year². At the summer solstice in 2026, a typical UK rooftop installation generated 15kWh in a single day³. But no home in these studies cut its imports to zero: winter, overnight demand and the limits of battery capacity all keep the grid in the picture.

What the case studies really tell us

Before taking any household number at face value, it helps to know how it was produced. "Case study" covers several very different kinds of evidence, and the strength of each differs.

The most robust figures come from metered studies. Energy Saving Trust published measured performance data from 546 homes, a sample large enough to smooth out the quirks of any single property⁷. Energy Systems Catapult's Metered Energy Savings project applied its methodologies to 42 UK homes, a smaller sample but one with real consumption data behind it⁸. Consumer surveys measure something different again: Ofgem's Energy Consumer Satisfaction Survey of January 2025 surveyed 3,854 domestic energy bill payers across Great Britain, including face-to-face interviews with digitally excluded respondents, so it captures experience rather than meter readings⁹.

Programme evaluations sit somewhere between the two. The Home Upgrade Grant Phase 1 evaluation drew on 10 case studies of local authority led projects¹⁰, and the Building for 2050 programme produced 4 in-depth case studies of low carbon housing schemes across England and Wales¹¹. The Electrification of Heat Demonstration Project recorded the first-hand experiences of 7 households taking part in the programme¹². The Social Housing Decarbonisation Fund Wave 1 impact evaluation included a thematic case study looking at local authorities outside the scheme¹³.

At the largest scale, Energy Systems Catapult runs a Living Lab of more than 5,000 UK homes trialling new technologies¹⁴, described as a trials and data facility of over 5,000 diverse UK households¹⁵ and comprising over 5,000 homes across the UK¹⁶.

What this means for a householder is simple: a single home's result is a data point, not a promise. The figures on this page are strongest where many homes were measured, and weakest where one household tells its own story.

Five real installations, and the stock they come from

The individual homes in this page sit within a fast-growing national picture. UK homes had 6.6GW of solar power installed as of May 2026⁶, and the UK Solar Roadmap records over 1.5 million domestic solar installations¹⁷. Official data shows 697,538 installations on detached houses alone, with installations smaller than 5MW accounting for 99.9% of total installations and 55% of installed capacity¹. The first half of 2026 saw almost 150,000 certified installations, a record pace¹⁸, and the Office for National Statistics tracks the energy efficiency of housing in England and Wales on a rolling five-year basis¹⁹.

Against that backdrop, the installations described below range from a 5.16kWp array with 13.5kWh of storage, through a 5.4kWp system costing £12,364, to a 3kWp array paired with a 10kWh battery and a 1.5kWp share of a larger array with 5kWh of storage²⁰. They differ in size, in cost and in what their households achieved, which is precisely why they are worth reading together rather than one at a time.

Simon's setup: 5.16kWp panels and a 13.5kWh battery

The first installation is a 5.16kWp solar array with 13.5kWh of battery storage: a system at the upper end of what a typical suburban roof and budget can accommodate. It belongs to the wave of installations that took UK homes to 6.6GW of installed capacity⁶, a wave driven in part by price volatility: Uswitch reported in May 2026 that three million households plan to get solar panels in the next five years, with two-fifths blaming energy price chaos⁶.

What does a system of this shape deliver? The 13.5kWh of storage is the figure that matters most for independence, because it determines how much of the day's generation survives into the evening. UK guidance states that a 10kWh battery can power a typical 3-bedroom house for about 12 hours⁵, so 13.5kWh gives a household more overnight cover than that benchmark. On a good summer day, when a typical installation generates 15kWh³, an array of this size can fill the battery and still have surplus to export.

The limits are just as real. A 13.5kWh battery covers overnight use, not a winter week. In December, generation falls to a fraction of the June figure, the battery may not fill, and the home imports as before. This is the pattern every documented UK installation shows: near-total self-sufficiency on bright days, and continued grid dependence through the winter gap, which is covered in detail in the winter gap.

£12,364 spent on a 5.4kWp solar and storage setup

The second installation is a 5.4kWp solar and battery system, documented at a total cost of £12,364. That figure is worth sitting with, because it is the price of entry for a whole-home generation and storage system rather than a token array. For comparison, published UK guidance puts a 2kW panel system without a battery at an average of £4,600 to £5,800²¹, and a 5kWh battery at £3,000 to £5,000⁵, so a 5.4kWp array with a substantial battery sits well above the sum of those smaller components.

What does a household of this kind use? The heatwave week of late June 2026 gives a snapshot. Uswitch's analysis of British homes with solar panels found that a high-usage household, with ten panels and 4,100kWh of annual consumption, earned £29.84 in total value over that week, combining bill savings of £24.47 with export earnings of £5.37⁴. A low-usage household, with five panels and 1,800kWh of annual consumption, earned £14.92 over the same week: £12.24 in savings and £2.69 in export earnings⁴.

Those are exceptional weeks, at the sunniest point of the year, and should not be annualised. What they show is the shape of the benefit: most of the value comes from power the household uses itself, and a smaller share from exports. Across the same week, British households with solar panels sold an average of 4.6kWh of electricity back to the grid per household per day, earning 55p⁴. Export matters, but self-consumption matters more, which is the whole argument for the battery.

Annual output of a 5kWp system: roughly 5,500kWh

A 5kWp array is the size most often quoted for a family home aiming at serious self-sufficiency, and its annual output is the number everything else depends on. The best-documented household figure comes from Energy Saving Trust's case study of Russell and Kate, whose household manages to use around 3,000kWh of its array's output each year². That is the self-consumed portion, not the total generation, and it shows how much of a family home's electricity demand can be met from its own roof.

Daily figures put the seasonal swing in plain terms. On 21 and 22 June 2026, a typical UK rooftop solar installation generated 15kWh, which Ember calculated as the equivalent of five hours of daily air conditioning use³. Across 1.88 million domestic-scale installations, that amounted to an average of 28.5GWh per day nationally³. Those are solstice figures: the annual average is far lower, and a winter day produces a fraction of that output.

MCS worked examples show how much of generation a home actually captures without storage:

• A household at home all day, with 3,879kWh of annual consumption and 4,059kWh of annual solar generation, self-consumed 29% of its output²².
• A household in for half the day, with 5,783kWh of consumption and 2,456kWh of generation, self-consumed 39%²².

The gap between generation and self-consumption is what the battery exists to close, and it is why self-consumption is the number to watch rather than raw output.

Why a 10kWh battery suits a 5kWp array

The documented installations point the same way: a 5 kWp solar PV system comes with a recommended battery capacity of 10 kWh²⁰. One Energy UK case study household installed an air source heat pump with radiators, a 3kWp solar PV array and a 10kWh battery²⁰. Another funded a connection to a shared loop individual ground source heat pump, a 1.5kWp share of a PV array and a 5kWh battery²⁰. In each case the battery is sized to the array and the home it serves.

The reason is arithmetic. A 5kWp array on a good June day generates 15kWh³, far more than a household uses while the sun is up. Without storage, 60 to 70% of that goes to the grid; with a battery sized to the surplus, most of it is kept. Great British Energy guidance states that adding a battery to a solar installation increases self-consumption from 30 to 40% to 70 to 80%¹. Uswitch's data points the same way, reporting a 70% self-consumption rate with a 10kWh battery⁴.

MCS's own worked example shows the mechanism: a household at home all day with 7.5kWh of usable storage capacity reached 69% self-consumption²³, against the 29% the same usage pattern achieves without storage²². For larger properties, UK guidance pairs a 6kW solar system with a 13 to 14kWh battery, at a cost of £10,000 or more⁵. The same guidance notes that a 10kWh battery generally needs 8 to 12 standard 400W to 450W panels to fill it⁵. Sizing is covered in full in sizing a self-sufficient home system.

Savings from a 5kW solar setup: £1,000 to £1,300 yearly

Savings figures vary with the home, the tariff and the year, so the honest answer is a range with its conditions attached. The official baseline comes from Hammersmith and Fulham Council's energy guidance: solar photovoltaic panels save between £530 and £650 a year on electricity bills for a typical home without electrical heating or an electric vehicle²⁴. That is for panels alone, and it is the figure a householder should treat as the floor.

The heatwave week of June 2026 shows what a high-generation week looks like in cash. A high-usage household with ten panels saved £24.47 on its bills in that week and earned £5.37 from exports, £29.84 in total⁴. A low-usage household with five panels saved £12.24 and earned £2.69, £14.92 in total⁴. Those weekly figures cannot simply be multiplied out: they come from the sunniest week of the year, and winter weeks look entirely different.

What pushes savings towards the upper estimates is the battery, because every kilowatt-hour used from the roof is a kilowatt-hour not bought. Raising self-consumption from 30 to 40% to 70 to 80%¹ roughly doubles the usable output of the same array without adding a single panel. The cost side of the ledger is covered in what energy independence costs, and the honest framing is this: the savings are real and measured, but they are earned over a decade or more, not in a single year.

Retrofitted AC-coupled options such as the AlphaESS SMILE-G3

Not every battery installation starts from scratch. A significant and growing group of households already have solar panels and want to add storage without ripping out the original inverter. The route that makes this possible is AC coupling: the battery and its own electronics connect on the household side of the existing solar inverter, leaving the original system untouched.

The AlphaESS SMILE-G3 is an example of the type. The maker states that it can be AC or hybrid-coupled and features VPP readiness, and that it can work with third-party solar inverters²⁵. AlphaESS describes systems like the SMILE-G3 as ideal for straightforward retrofitting due to their hybrid nature, suitable for on-grid or off-grid use²⁵. Those are the maker's own claims about its own product, and they should be read as such, but the underlying capability, adding storage to an existing array, is well established across the market.

Official routes exist too. Solar Together Norfolk, a council-backed group-buy scheme, lets households that already have solar panels register to have battery storage added to maximise the benefits of their system²⁶. At the smaller end, the government's plug-in solar work defines devices intended for connection to an existing low-voltage electrical installation using a standard UK mains plug and socket, without requiring a separate electrical circuit for export²⁷, and the consultation describes plug-in solar systems without batteries connected directly to a standard mains socket²⁸. The distinction between these small plug-in kits and a full AC-coupled battery is capacity: one tops up a bill, the other changes a home's self-sufficiency ratio. The trade-offs are compared in hybrid inverter vs AC-coupled battery.

The figures explained: what they mean for energy self-sufficiency

Taken together, these case studies support a clear and bounded conclusion. A UK home with a 5kWp-class array and a 10kWh-class battery can, on the evidence here, use 70 to 80% of its own generation¹, cover its overnight consumption from storage⁵, and cut its imported electricity substantially. It cannot, on this same evidence, dispense with the grid: winter generation, battery limits and the seasonal mismatch keep imports in every documented case. Whether full self-sufficiency is possible at all is examined in can a UK home be fully self-sufficient.

The motivation is not only financial. Average required energy costs were 6.8% of household income for all households in England in 2025 (provisional)²⁹. The House of Commons Energy Security and Net Zero Committee reported that 36.4% of households in England, some 8.91m, were spending more than 10% of their income on domestic energy after housing costs in 2023, up from 20.5% (4.93m) in 2021³⁰. Against that backdrop, three million households plan to get solar panels within five years⁶, and almost 150,000 certified installations were completed in the first half of 2026 alone¹⁸.

The remaining barriers are practical rather than technical. The Chartered Trading Standards Institute found that 43% of homeowners are actively considering installing energy-efficiency measures, but estimates as many as 5 million UK households are deterred by unfamiliarity or a lack of a reliable installer³¹. Support also varies by nation: Energy Company Obligation measures averaged 118 per 1,000 households in Scotland, compared with 81 in Wales and 77 in England³². The systems in these case studies work, the numbers are measured, and the dependence that remains is the grid in winter, not the technology.