How this house compares

The solar panels have paid this house a Feed-in Tariff since 2012, about £1,100 a year and roughly £15,000 so far, much of it reinvested in the other retrofit measures. In 2025 this house heated itself and made its hot water on about a ninth of the energy a typical home uses for gas, made about two-thirds of a typical home's electricity on its own roof, and ran an electric car on about a quarter of the carbon of the same miles in a petrol one. In money, the house's whole 2025 electricity bill was about £480, against about £2,950 for a typical home's gas and electricity plus the petrol for the same miles (an illustration). These are comparisons with national figures, not with this house before it changed.

The panels pay for the rest

Before any comparison, one fact about the money. The solar panels have paid the household a Feed-in Tariff for every unit they generate since they were installed in 2012: about £1,100 a year by the homeowner's account, roughly £15,000 so far (an estimate: about £14,000 if the payments rose steadily from about 49p a unit, about £16,000 if they had always been £1,100). The household has reinvested much of that money in the other retrofit measures. The scheme closed to new applicants in 2019, so it is one household's outcome and not something a new installation can earn; it is left out of the comparisons with a typical home below and shown on its own. Against the house's electricity bill in 2025 (about £440 after exports, see "What it costs"), £1,100 means the electricity was more than paid for, about £660 ahead. The story "How it was paid for" sets it beside what each later measure cost.

What it is compared with

There is no measured "before" for this house, and none is invented here. The figures below are set against the national median home in England and Wales: about 10,100 kWh of gas and 2,600 kWh of electricity a year (the government's NEED statistics, for 2023). That is not a house like this one: it covers every age, type and size of home, and the same report finds that older homes use more gas, so a home of this age would probably have been above it. This house's own figures are for 2025, from the heat pump, solar and charger apps and the Octopus app, so they are estimates, read by eye in places. Two people live here.

Heating and hot water

The heat pump used about 1,150 kWh of electricity in 2025, by its app's estimate, to heat the house and make its hot water. That is about a ninth of the 10,100 kWh of gas the median home uses, though that gas also covers cooking. At the UK government's 2025 carbon factors it is roughly 200 kg of CO2e against roughly 1,850 kg. This house uses no gas at all. Gas and electricity are not interchangeable, though. A gas boiler turns each kWh of gas into a little under a kWh of heat, while a heat pump turns each kWh of electricity into about three. So the heat that 10,100 kWh of gas gives would take a typical heat pump roughly 3,000 kWh of electricity. That is a modelled figure: it assumes about 83 percent efficiency for a combi boiler in a home, as measured in a field trial (this house had a combi boiler), and a seasonal figure of 2.8 for air-source heat pumps, the median in a government-funded trial of 291 of them; the gas also covers cooking, which a heat pump would not replace. This house's heat pump used about 1,150 kWh, about 40 percent of that. A heat pump's efficiency explains much of the move from gas to electricity. The remaining gap can reflect both how much heat this house needs (its size, its insulation, how warm it is kept and who lives in it) and differences in seasonal heat-pump efficiency: this house's own has not been measured, and the 2.8 is a median that half of the sampled heat pumps beat. This comparison cannot separate those effects.

Electricity and the roof

The median home uses 2,600 kWh of electricity a year and, on top of that, 10,100 kWh of gas. This house uses no gas, so its electricity also does the heating, hot water and cooking. The panels made roughly 1,750 kWh in 2025, about two-thirds of that 2,600 kWh. The house took 3,693 kWh from the grid, about 40 percent more than the median home's electricity, but that includes charging the car, which the median home has no equivalent of. The charger's app cannot say where the car's charge came from, but the homeowner reckons the vast majority of it came from the grid, as it is mostly charged overnight, when the panels make nothing. Taking 90 percent as a working figure, the car drew about 1,900 kWh from the grid, which leaves about 1,800 kWh for the house on its own: about 30 percent below the median home's 2,600 kWh of electricity, and with none of its 10,100 kWh of gas. That rests on the 90 percent, which is an assumption and not a record; even if only about half of the car's charge had come from the grid, the house's electricity would be level with the median's, still with no gas. The gas and the electricity are set side by side and not added into one figure, because medians cannot be added.

The car

The car took roughly 2,100 kWh from its charger in 2025. At the same carbon factors that is about 370 kg of CO2e, against about 1,430 kg for the same miles in a petrol car doing 45 miles to the gallon. That is a comparison with a petrol car, not with a house; the electric car story has the working and the cost of a trip.

What it costs

The Octopus app estimates the house's electricity for 2025 at £481.61, standing charge included, on Intelligent Octopus Go. That one bill covers everything: heating, hot water, cooking, the car and the rest of the house, because there is no gas. The roof's exports added a little: roughly 300 kWh a year at 12 to 15p a unit, about £40, worked out from the months since Octopus began paying for exports in autumn 2025 (the app shows about 280 kWh for January to mid-October 2026). Taking that off leaves about £440. For comparison, Ofgem's typical dual-fuel household bill through 2025 was about £1,750 (£1,738 from January and £1,849 from April, easing in July), which pays for gas and electricity but for no car. The same 6,800 miles in a 45 mile-to-the-gallon petrol car at about 174p a litre would add about £1,200 of fuel. Together that is about £2,950, against about £440 here: roughly £2,500 a year less. These are illustrations of scale, not bills. A typical bill is not this house's old bill, which was never measured; the car's miles, the tariffs and the weather differ from house to house; and the figures count running costs only, not what the equipment cost (that is in "How it was paid for"), with no payback claimed.

What this does not show

It does not show what this house used before, which was never measured. It does not show payback. What the equipment cost is in the related story "How it was paid for": about £31,300 of the household's own money on the measures after the panels, about £37,500 with them. This page sets running costs against typical homes, not against that spending, and its costs are illustrations, not bills. Every figure is for one household in one year, the national medians are for an earlier year and for every kind of home, and the weather and energy prices of the two years are not adjusted for. Treat the comparison as the scale of what is possible, not as a prediction for another house.

Benefits

The panels' Feed-in Tariff, about £1,100 a year by the homeowner's account and roughly £15,000 since 2012, much of it reinvested in the other retrofit measures; it is more than the house's whole electricity cost of about £440 in 2025, about £660 ahead (a legacy scheme, closed to new applicants in 2019; one household's outcome, not a prediction).
Heating and hot water on about a ninth of the energy, and the carbon, of the gas a median home uses (roughly 200 kg of CO2e against 1,850 kg).
Against the roughly 3,000 kWh of electricity a typical heat pump would need to give a median home's heat, this house's heat pump used about 40 percent as much (a model; see the story).
No gas at all: the gas supply was disconnected.
About two-thirds of a median home's electricity made on the roof.
Even counting the car, grid electricity was only about 40 percent above a median home's, and on the homeowner's estimate about 30 percent below it for the house on its own, with none of the gas a median home uses on top (see the story).
The car's carbon about a quarter of the same miles in a petrol car (an illustration).
Running costs of about £440 in 2025 (the Octopus app's £481.61 less about £40 of export income) for everything, the car included, against about £2,950 for a typical home's gas and electricity plus petrol for the same miles: roughly £2,500 a year less (an illustration; running costs only).

Limitations

There is no measured before-state for this house, and the comparison does not pretend there is.
How much of the car's charge came from the grid is not recorded: the house's own grid use rests on the homeowner's estimate of 90 percent.
The 3,000 kWh is a model, not a measurement: it assumes typical efficiencies from two field trials (a combi boiler at 82.5 percent, an air-source heat pump at 2.8), and the gas figure also covers cooking.
The national figures are medians for 2023 for every kind of home, not a house of this age, type and size; this house's are app estimates for 2025.
Floor area is not compared: the median covers all sizes, and this house is compact. Two people live here; the national household size is not used.
Weather and energy prices are not adjusted for. The costs are illustrations of scale: Ofgem's typical bill is not this house's old bill (never measured), the equipment's cost is not counted here (it is in "How it was paid for"), and no payback is claimed.
The carbon figures are approximate illustrations using the UK government's 2025 factors, not measurements.
The export income rests on an extrapolation: Octopus only began paying for exports in autumn 2025, so a full year is estimated at about 300 kWh from the months since.
The Feed-in Tariff is the homeowner's approximate figure and a legacy scheme that closed to new applicants on 31 March 2019; it is kept out of the comparison with a typical home and shown separately. The roughly £15,000 since 2012 is an estimate between two cases (payments rising steadily from about 49p a unit, and always £1,100).