Renewable energy advice
Renewable energy for your home: what to fit, and in what order
Heat pumps, solar panels and batteries can cut what a home takes from the gas main and from the grid. Whether they pay their way depends on the building they are fitted to. We do not sell or install any of them, which leaves us free to tell you what the survey shows.
- Heat pump efficiency
- Up to 3 to 4 units of heat per unit of electricity
- Typical heat pump cost
- Around £12,000 before the grant
- Typical solar PV system
- 4.5 kWp, around £7,600
- Installer standard
- MCS certified
- VAT on energy-saving measures
- 0% in homes until 31 March 2027
Reviewed October 2026
Start with the building
A heating system works better, costs less to run and can be smaller when the home it serves holds its heat. That matters most for a heat pump, which is sized to the heat the home loses. So the usual order runs from the fabric outwards.
- Find out where you stand. An EPC or a retrofit assessment records how the home is built, insulated, heated and ventilated.
- Stop the easy losses. Loft insulation, cavity wall insulation, draught-proofing and heating controls are the cheapest gains in most homes.
- Deal with ventilation at the same time. A home made more airtight without fresh air invites condensation and mould.
- Change the heat source. A heat pump sized for the heat the home now loses.
- Generate and store. Solar panels, with a battery if the numbers work for you.
That order is a guide, not a rule. If the boiler has failed, a heat pump can go in first, provided it is designed for the house as it is. The Energy Saving Trust is clear that a home can use a heat pump without being fully insulated. And solar panels do not depend on insulation at all.
The technologies, in brief
Air source heat pumps
Take heat from the outside air, and can deliver three to four units of heat for each unit of electricity they use. Around £12,000 to install, with a £7,500 grant available. Read the guide.
Solar panels
Generate electricity from daylight. The Energy Saving Trust puts an average 4.5 kWp home system at around £7,600. Read the guide.
Battery storage
Stores surplus solar power, or cheap-rate electricity, for use later. Around £4,600 for a 5 kWh battery, with a typical life of 10 to 12 years.
Ground source heat pumps
Take heat from pipes buried in the ground. They cost more to install and need outdoor space, and attract the same £7,500 grant.
Costs are the Energy Saving Trust's typical figures, checked October 2026. Yours will depend on the property.
What is new
- Plug-in solar. Since 27 August 2026 small plug-in solar kits of up to 800 watts have been legal to use in Great Britain. The Energy Saving Trust says a kit must meet set standards and be registered before it is used. The government says one could save a household up to £110 a year. They suit a garden or a patio, and they are no substitute for a full system on the roof.
- Air-to-air heat pumps. These heat and cool rooms directly. The Boiler Upgrade Scheme now lists a £2,500 grant for them in homes.
- Simpler planning rules. In England a heat pump no longer has to be a metre from the boundary to count as permitted development, and the rules for solar panels were updated in August 2026.
- New homes. In England, new homes built to the Future Homes Standard, in force from 24 March 2027, will have low-carbon heating and on-site renewable electricity. Homes already under way can follow the old rules for a transition period.
- A new kind of EPC. The certificate due in the second half of 2027 will rate the heating system and a home's readiness for smart, flexible energy use alongside its running cost.
What renewables do to an EPC
Today's EPC rating is a measure of running cost, which produces two results people do not expect.
- Solar panels usually raise the rating. The electricity they generate is counted in the calculation. Since June 2025 a battery or a solar diverter can be recorded too.
- A heat pump may not. Electricity costs more per unit than gas, so replacing a gas boiler with a heat pump can leave the rating unchanged or lower, even though the home uses far less energy. Both the Energy Saving Trust and Elmhurst Energy have pointed this out.
The reformed certificate is designed to put that right by rating the heating system as a measure of its own. Until then, do not judge a heat pump by the EPC band alone. Ask us what the numbers mean for your home.
Keep the paperwork
An assessor can only record what can be seen or proven. For solar panels, a battery or a heat pump, the MCS certificate shows what was installed and how large it is. Without it we have to estimate, and estimates are cautious.
Grants, VAT and export payments
- Heat pumps: £7,500 through the Boiler Upgrade Scheme in England and Wales.
- Low-income households: insulation, solar panels and heat pumps through the Warm Homes: Local Grant, where the council has funding.
- Everyone: no VAT on installing listed energy-saving materials in a home, including insulation, heat pumps, solar panels and batteries, until 31 March 2027.
- Solar panels: payment for exported electricity under the Smart Export Guarantee.
Our guide to grants and schemes has the detail, including who qualifies.
Choosing an installer
MCS is the UK's quality mark for small-scale renewable energy. It certifies both the products and the firms that fit them. You need an MCS certified installer to claim the Boiler Upgrade Scheme grant, and certification through MCS or an equivalent scheme to join a Smart Export Guarantee tariff.
- Ask for more than one quote, and for the design calculations behind each.
- Check the installer on the MCS and TrustMark websites.
- Make sure the system is registered with the local electricity network operator. Heat pumps, solar panels and batteries all have to be.
- Keep the MCS certificate, the commissioning record and the guarantees.
Planning permission, in brief
In England, most heat pumps and solar panels on a house are permitted development, which means no planning application is needed if the installation stays within set limits. Listed buildings are excluded, conservation areas have extra restrictions, and a council can remove the rights for a particular street or estate. Check with your council before work starts. The detail is in our heat pump and solar guides.
How we help
- A survey that shows how well the home holds heat and what is worth doing first
- Modelling of what each change would do to the EPC rating
- A retrofit assessment and coordination where the work follows PAS 2035
- A new EPC afterwards, so the improvement is on the public register
Warm Homes schemes, social housing and installers
Retrohaus Energy Consultancy provides retrofit assessment and retrofit coordination for homes improved under Warm Homes schemes, working with social housing providers and local authorities. We also support solar PV and air source heat pump (ASHP) installers, including the work they deliver under grant schemes.
Sources: Energy Saving Trust guides to air source heat pumps, solar panels, battery storage and improving an EPC rating (updated September and October 2026); GOV.UK, Boiler Upgrade Scheme, Smart Export Guarantee, the announcement on plug-in solar (26 August 2026), the Future Homes and Buildings Standards circular (24 March 2026) and guidance on registering energy devices; HMRC VAT Notice 708/6; Planning Portal; MCS; Elmhurst Energy on RdSAP 10 (May 2025) and on heat pumps and EPC ratings (September 2025). This page is general guidance, not a recommendation for any particular property.
Renewable energy questions
Before you ask for quotes.
Should I insulate before fitting a heat pump or solar panels?
Where insulation is cheap and effective, such as a loft or an unfilled cavity wall, doing it first usually means a smaller heating system and lower bills. It is not a condition: the Energy Saving Trust says a home can use a heat pump without being fully insulated, provided the system is designed for the heat the home loses. Solar panels do not depend on insulation at all.
Will a heat pump or solar panels improve my EPC rating?
Solar panels usually raise it. A heat pump may not: today's rating is based on running cost, and because electricity costs more per unit than gas, replacing a gas boiler can leave the rating unchanged or lower. The new-style certificate due in the second half of 2027 will rate the heating system as a measure of its own.
Do I need planning permission?
Usually not for a house in England. Most heat pumps and solar panels are permitted development, within limits on size and position. The rules are tighter in conservation areas, and listed buildings are excluded and need consent. Ask your council before work starts.
What is MCS and why does it matter?
MCS is the UK's quality mark for small-scale renewable energy. It certifies products and installers. You need an MCS certified installer to claim the Boiler Upgrade Scheme grant, and certification through MCS or an equivalent scheme to be paid for exported electricity under the Smart Export Guarantee. The MCS certificate is also the evidence an energy assessor uses to record the system on your EPC.
Do you install heat pumps or solar panels?
No. We assess buildings and coordinate retrofit projects. That independence is deliberate: our advice is not shaped by what we have to sell. We do work with installers, providing the assessments and coordination that funded schemes require.
Is there a grant for solar panels?
There is no national grant for solar panels that works like the Boiler Upgrade Scheme. Eligible low-income households can have solar panels fitted through the Warm Homes: Local Grant. Everyone else benefits from zero-rate VAT on installation until 31 March 2027 and from export payments under the Smart Export Guarantee.