The short answer
- Most houses in England can have an air source heat pump and roof-mounted solar panels without planning permission, as permitted development.
- Since 29 May 2025, a heat pump no longer has to be 1 metre from the boundary, units can be up to 1.5 m³ and detached houses can have two.
- Roof panels must not stick out more than 20 cm from the roof slope or rise above the highest part of the roof.
- Listed buildings, conservation areas, flats and homes under an Article 4 direction have extra rules, so they need checking first.
Permitted development explained
Permitted development rights let you carry out certain work without applying for planning permission, as long as it meets set limits and conditions. For homes in England, the rules for heat pumps and solar panels are in Part 14 of the General Permitted Development Order.
If an installation meets every condition, you don't need to apply to the council. If it doesn't, you can still apply for planning permission in the normal way. The rules on this page are for England; Wales has its own.
Air source heat pumps
The rules were relaxed on 29 May 2025. The old requirement to keep the heat pump at least 1 metre from your boundary was removed, the size limit went up and detached houses can now have two units. An air source heat pump on a house is permitted development if:
- there's no more than one on the property, or two on a detached house
- the outdoor unit is no bigger than 1.5 m³ (0.6 m³ on a block of flats)
- it meets the MCS 020(a) sound calculation, which limits the noise reaching your neighbours' windows
- it isn't on a pitched roof, and on a flat roof it's at least 1 metre from the edge
- it isn't above ground floor level on a wall that faces a road
- there's no wind turbine on the house or in the garden
- it isn't used solely for cooling
It should also be placed, as far as practical, to limit its effect on how the building looks and on neighbours, and removed when it's no longer needed. A typical 5–12 kW domestic heat pump is well under the 1.5 m³ limit.
The rules cover air-to-air heat pumps too, as long as they're used for heating. A unit used only for cooling, such as some air conditioning systems, isn't covered, so check with your council first.
Ground source heat pumps
A ground source heat pump on a house or block of flats is permitted development without size or siting limits, because the pipework is buried and the heat pump itself sits indoors. If your home is listed, the work inside may still need listed building consent.
Solar panels on your roof or walls
Solar panels on the roof of a house are permitted development if:
- they don't stick out more than 20 cm from the roof slope
- they don't rise above the highest part of the roof, not counting the chimney
- on a flat roof, they're no more than 60 cm above the highest part of the roof
- the house isn't a listed building or a scheduled monument
Since 27 August 2026, panels on the walls of a house are permitted development too, as long as they stick out no more than 20 cm on a wall next to a road, or 40 cm elsewhere.
Panels should be placed, as far as practical, to limit their effect on how the building looks. On a flat roof in a conservation area, National Park, National Landscape (formerly Area of Outstanding Natural Beauty) or World Heritage Site, you need to ask the council whether it wants to approve the appearance before work starts. This is called prior approval.
Solar panels in the garden
Free-standing solar panels in the garden of a house are permitted development within these limits:
| Where the panels go | Maximum height |
|---|---|
| Within 5 m of the boundary and in front of the house | 1 m |
| Within 5 m of the boundary elsewhere | 2 m |
| Everywhere else | 4 m |
The panels can cover up to 9 m² in total and can't be in the grounds of a listed building. In a conservation area, panels nearer the road than the house are limited to 2 m and need prior approval. In a National Park, National Landscape or other protected area, panels within 5 m of the boundary also need prior approval.
Conservation areas, National Parks and listed buildings
| Where | Heat pump | Roof solar |
|---|---|---|
| Conservation area or World Heritage Site | Not on a wall or roof facing a road, or nearer the road than the house | Allowed on roofs, but not on a wall, balcony or roof enclosure facing a road. Flat roofs need prior approval |
| National Park or National Landscape | Same rules as elsewhere | Same rules as elsewhere. Flat roofs need prior approval |
| Listed building | Needs planning permission and listed building consent | Needs planning permission and listed building consent |
Councils can also remove permitted development rights in a particular street or area with an Article 4 direction. These are most common in conservation areas, so we check your council's list before we design your system.
Locally, that means the New Forest National Park Authority inside the park, and New Forest District Council, BCP Council or Southampton City Council elsewhere. Our area pages for Lymington and the New Forest, Christchurch, Bournemouth, Poole and Southampton cover the local details.
Flats and apartments
For a block of flats, the limits are tighter: one air source heat pump on the building, with an outdoor unit no bigger than 0.6 m³. Roof-mounted solar panels on a block of flats follow similar limits to houses.
If you own a leasehold flat, you'll usually need the freeholder's written consent as well, because the outside walls and roof normally belong to them.
How we check your home
At your survey, we:
- check whether your home is listed, in a conservation area, in the National Park or under an Article 4 direction
- choose a position for the heat pump and run the MCS 020(a) sound calculation
- confirm the size and position of solar panels against the permitted development limits
- apply for planning permission or prior approval on your behalf if your installation needs it
That's part of every heat pump and solar panel installation we carry out. If you're planning a heat pump, our Boiler Upgrade Scheme guide explains the £7,500 grant.
Common questions
Do I need planning permission for a heat pump in a conservation area?
Not usually, but the heat pump can't go on a wall or roof that faces a road, or closer to the road than the house. Most installs go on a side or rear wall, or on the ground at the side or back.
Can I put solar panels on the front of my house in a conservation area?
Roof panels on a front-facing roof slope are still permitted development in a conservation area, as long as they don't stick out more than 20 cm or rise above the ridge. Panels on a wall, balcony or roof enclosure facing the road are not.
Is the New Forest National Park treated differently?
The heat pump rules are the same as elsewhere. For solar, panels on a flat roof and free-standing panels within 5 metres of your boundary need the planning authority to confirm whether it wants to approve their appearance first.
Do I need to tell the council before installing a heat pump?
Not if the installation meets all the permitted development conditions. If you want written confirmation, for example to show a buyer later, you can apply for a Lawful Development Certificate.