For Clare Naylor and her family, winter heating once meant keeping a close eye on the energy meter.
asserted
heating → mean → meter
The Milton Keynes household used hot-water bottles, extra blankets and jumpers to make sure its heating costs stayed within budget.
asserted
costs → use → budget
That has changed after their four-bedroom detached house was fitted with solar panels, a heat pump and a large battery.
asserted
house → change → panels
The retrofit has effectively turned the property into a small power station, allowing it to generate and store electricity and send surplus power back to the grid.
asserted
it → turn → grid
The family can now use Octopus Energy’s Zero Bills tariff, which guarantees no energy bills for five years as long as the household stays within its agreed fair-usage limit.
asserted
household → use → limit
How the Naylors turned their home into a mini power station
The Naylors’ home in Milton Keynes was built in the 1980s, but it has recently undergone a major energy retrofit.
asserted
it → turn → retrofit
The property now has 17 solar panels, a heat pump, a large battery in the garage and four new radiators.
asserted
property → have → garage
Together, the equipment allows the house to produce electricity, store it and use it for heating and everyday household needs.
asserted
house → allow → heating
The changes mean the home can operate under Octopus Energy’s Zero Bills tariff.
asserted
home → mean → tariff
The system is designed around homes that generate slightly more energy over the course of a year than they are expected to consume.
asserted
they → design → year
Surplus electricity can then be sold back to the grid, helping to support the economics of the tariff.
asserted
electricity → sell → tariff
For the Naylor family, that means their home is no longer simply consuming energy from the grid.
asserted
home → mean → grid
It can also produce and store energy, making the property function more like a small-scale energy system.
asserted
property → produce → system
Solar panels, battery and heat pump work together
Each part of the retrofit has a different role.
asserted
part → work → role
The solar panels generate electricity, while the battery stores energy so it can be used when required.
asserted
it → generate → energy
The heat pump replaces the household’s gas boiler as the main source of heating.
asserted
pump → replace → heating
The property also needed four new radiators as part of the upgrade.
asserted
property → need → upgrade
To qualify for the Zero Bills tariff, the house cannot use gas, including for cooking, so the family had its gas boiler removed.
asserted
boiler → qualify → cooking
Nigel Banks, technical director of Zero Bills at Octopus Energy, told The Guardian that properties generally need good insulation alongside solar panels, a heat pump and a battery.
asserted
properties → tell → panels
The aim is for the home to generate enough energy to cover its expected use, with additional electricity potentially sold to the grid.
asserted
home → generate → grid
The tariff does come with conditions.
asserted
tariff → come → conditions
The Naylor family must stay within a fair-usage limit, while charging an electric vehicle is not covered by the zero-bill promise.
asserted
charging → stay → promise
the heat pump installed at the rear of Clare Naylor’s home (Image: Teri Pengilley/The Guardian)
The family used to spend about £130 a month on energy
Before the retrofit, the Naylors were already relatively careful with their energy use.
asserted
Naylors → instal → use
Clare Naylor told The Guardian that the household generally kept the heating at 18C, increasing it only when family members visited.
asserted
members → tell → it
During colder periods, the family relied on slippers, hot-water bottles and jumpers to stay comfortable without pushing up their bills.
asserted
family → rely → bills
Under the new arrangement, Naylor says that money can instead go towards holidays.
asserted
money → say → holidays
The difference is also changing how the family plans to use its home.
asserted
family → change → home
Naylor said she intends to heat the house before her children return from school, something the family did not previously do because of the need to keep energy spending under control.
asserted
family → say → control
The change comes as British households face higher energy costs.
asserted
households → come → costs
The price cap rose by 4% on 1 October 2026, while a further increase had been predicted for January.
asserted
increase → rise → January
The retrofit would have cost almost £20,000
The technology came without an upfront cost for the Naylors because Santander funded the retrofit as part of a project examining ways to improve the energy efficiency of existing homes.
asserted
Santander → cost → homes
The solar panels, heat pump and battery would have cost just under £20,000 after a government grant if the family had paid for the work itself.
asserted
family → cost → work
The project also highlights one of the biggest challenges in making older homes more energy efficient, financing the upfront cost.
asserted
homes → highlight → cost
Santander is exploring ways to help households fund retrofits, while its existing home-improvement loan would mean repayments of £389 a month over five years for a £20,000 project at an interest rate of 6.4%.
asserted
loan → explore → %
Octopus Energy's Zero Bills tariff has already been used in hundreds of new-build homes since its launch five years ago.
asserted
tariff → use → launch
The company is now testing whether the model can work in older properties that need retrofitting, using the Naylors' home as an example.
asserted
that → test → example
For the family, the immediate result is a home that can generate and store much of the energy it needs while avoiding energy bills under the tariff's five-year guarantee.
asserted
it → generate → guarantee
As Naylor prepares for winter, she plans to keep the house consistently warm and, she jokes, teach her children to remember to keep the doors shut.
asserted
she → prepare → doors
The Aporia
