Cutting your home’s carbon footprint — and your energy bills — does not come cheap. Take solar panels. Not everyone can fork out a £7,100 lump sum to fit these on a three-bedroom house. That’s the average price of a typical 3.5kWp installation of ten panels, according to the Microgeneration Certification Scheme, which registers solar arrays.
However, a new generation of energy technology, or entech, enables you to spread the cost of going green without paying a large amount upfront. We look at two trailblazing platforms — one for new-build properties and the other for existing homes.
For new-build homes: Wondrwall
Michael and Tamara Dyble live in an experiment. Their four-bedroom new-build in Hull was built as a concept house to test whether solar panels combined with artificial intelligence could create a zero-carbon home. “We haven’t had to adjust our behaviour to cut our bills — the house learns. You don’t have to think about it, it just does it,” says Michael, 38, a store manager who bought the house in December 2022.
Now the first financial model of its kind in Britain could make such “net-zero energy” new-builds available with no upfront costs to the homebuyer or homebuilder. Wondrwall, the company behind the renewable tech in the Dybles’ home, is launching a monthly service charge to roll out the same kit to new homes across Britain. The cost? About £60 a month in a typical four-bedroom new-build house.
These energy service contracts would remove the “green premium” from new homes, Wondrwall claims. “It is like offering homeowners a self-driving electric car, for the same cost as a dirty diesel but with lower running costs,” says Daniel Burton, the founder and chief executive of Wondrwall Group. Last year the company secured up to £100 million investment to expand into 100,000 homes.
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Only 4 per cent of homes are built with the top energy performance certificate (EPC) rating of A, of which an even smaller subset are net-zero carbon. Commercially this is because building sustainably pushes up construction costs for housebuilders — and house prices for buyers, Burton says. “But we don’t want to carry on building houses where we have to retrofit them in ten or twenty years’ time.”
So how does the tech work that could help to change this? The Dybles’ house has a brain. Nineteen smart light switches and a controller learn how the couple, with their children, Rex, five, and Clara, one, use the house and how the building performs. It then optimises clean energy generated on the roof from a 2.1kWp system of seven solar panels with a hybrid inverter; gas-free heating through electric infrared panel heaters with individual thermostats; and hot water from a smart cylinder that warms just enough water for their needs.
A 6kWh battery saves their solar energy for use at night and recharges from the grid in the early hours when electricity rates are cheapest. Unlike nine in ten British homes, they do not burn any gas or oil.
For this type of system — worth more than £10,000 upfront — Wondrwall says you would pay a fixed service charge of £696 a year while saving £1,001 in annual energy costs. The savings, calculated from the Dybles’ actual energy bills, are made up of £367 in self-consumed solar energy, £403 from using off-peak energy and £231 from selling energy back to the grid at peak times. The idea, Burton says, is to make sure “that the homes are saving enough energy to cover what they’re paying as a standing charge”.
The service charge rises annually with inflation and is payable for 20 years. It is separate from your energy bill, so you are free to switch electricity suppliers. The contract is linked to the deeds of the property so it will transfer to the new owner if you sell. After ten years you get a free battery and inverter upgrade. You can exit at any time by paying the outstanding cost of the hardware as calculated by Wondrwall.
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“Our cheapest electricity bill was £13 last June,” Michael says. At the height of summer the family generate almost all their own energy. In winter, when there is less sunshine, their bills peak at £200 a month. Over the past year the family paid about £1,300 for all their energy. That, Michael says, is less than the £1,600 they paid annually for gas and electricity at their previous home, a two-bedroom property. “Our bill is cheaper in a house that is double the size, on the rate that electricity has gone up in price.” They still use a tumble dryer, a second fridge-freezer and a wine cooler, he adds.
Each Wondrwall light switch contains 13 sensors, including motion, luminosity, humidity and temperature. The system can turn off lights and radiators in rooms when they are not in use, and can be programmed to suit the family schedule. “Our lights come on automatically at dusk,” Michael says.
They voice-control the system via Alexa devices in every room, or by speaking while touching the light switch. Rex has a child profile that limits what the five-year-old can control. “If he gets into trouble and we send him upstairs, he can’t just turn the house off from his bedroom,” Michael says.
When the family is away or goes to sleep, Wondrwall activates the alarm, which listens for the sound of broken glass and automatically puts on lights to make it look like someone is home.
“The infrared heating takes a bit of getting used to,” Michael adds. The panels heat objects rather than the air. “If you stand directly underneath a panel it feels like standing in the sun. But if you move away it takes longer to warm the ambience of the room.”
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Wondrwall can also work with air source heat pumps. The heating system depends on what the housebuilder decides to fit, Burton says. Infrared heating is usually cheaper to fit than heat pumps, he adds.
Michael, whose Wondrwall kit was included when he bought the house for £235,000, says he likes it so much that he would retrofit the smart light switches in their next house if they moved.
The property was marketed with an EPC rating of B before the Wondrwall system was fitted. With the kit it outperformed the EPC predictions. The house emitted 502kg carbon in the past year, a fifth of the 2.6 tonnes of carbon expected in its EPC modelling. While that makes it a low-carbon home, it is not quite zero-carbon.
For existing homes: Otovo
This month Otovo launched a “leasing” option for solar panels in the UK. The subscription model by the Norwegian solar marketplace company allows customers to have solar panels installed on their homes for a monthly fee, rather than having to pay thousands of pounds upfront.
Customers pay £61 a month or £732 a year, with the price going up by 2.5 per cent every year. There is no down payment and the company will take care of the installation and upkeep of the panels, which come with a 20-year warranty.
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Unlike a traditional leasing model, where customers are just lending their roof space to a company for a fixed period of time, customers will own the panels outright after 20 years — and the battery after 10 years. They can also buy them out at any time during the payment plan.
“Most people can’t afford to spend £8,000 or £10,000 in one go for solar panels,” says Otovo’s general manager, Jina Kwon, who adds that the model will “democratise” access to solar energy in the UK. She explains that the company is only working with Bloomberg Tier 1 photovoltaic manufacturers to make sure that they will be around in 20 years’ time when the guarantee expires.
The UK is the 13th country in Europe in which Otovo is offering such a leasing model, following countries such as Germany, Sweden, Spain and Portugal. In Norway the scheme has been running for four years.
Merete Mundal Aarskog, who works for a British company but lives north of Oslo, had her panels installed in May last year. Aarskog, 48, owns a four-bedroom house with a large garden, a greenhouse, a hot tub and a garage. She also has an electric car, a Tesla, which she charges overnight.
Aarskog had wanted to buy solar panels for some time but because these are in high demand in Norway she had to join a waiting list. “You see the sun rising every day and it produces a lot of energy that we don’t take advantage of,” she says. “I think it’s so meaningful to be able to harness all this energy. Energy is going to be such a huge issue and is going to affect us all. It’s great that even people who wouldn’t be able to afford to buy solar panels can use them and contribute to the greater good.”
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Otovo was one of the energy companies Aarskog received a quote from. “I had to turn them down because it was too expensive for me, but they said they had this solution where you can rent them,” she says. “I signed the contract and they contacted me the same day to arrange for a date to put up the scaffolding. It was very quick. The upside is that I can purchase them at any point. I can buy myself out of the lease.”
Her motivations were both idealistic and financial. Norway has experienced a high volatility of energy prices since the start of the war in Ukraine. In Aarskog’s region electricity prices spiked to 4.5 krone a kWh (about 35p a kWh) in September 2022, a staggering 35 times higher than what they were in September 2020. In comparison, UK consumers “only” saw electricity prices double during the same period.
Prices in Norway have since decreased significantly but they’re still higher than in the UK. Aarskog pays about £97 a month for her 14 solar panels. In early March these produce more than two thirds (or about 17kWh) of the energy that she consumes every day (about 24kWh), but in the summer they generate so much energy (up to 50kWh a day) that her energy bill is zero, and the surplus is added to the following month.
Before having the system installed she was paying about 1500 krones (£110) a month. “Last summer I was producing maybe twice the amount of kilowatts that I need for my house and the extra electricity is sold to my energy provider,” she says.
During winter, though, the panels produced almost no energy at all. “It’s not very efficient because of the six months of darkness we have here. It’s not as bad as it is in the north of the country. We’re lucky, but we had so much snow.”
Aarskog is now considering installing a battery as well to keep the energy the panels produce during spring and summer.
“[Installing the panels] was the right thing to do,” she says. “I did this because it’s meaningful. It matters. The fact I can save money is just a benefit.”
