Yes, new homes in England will have to come with solar panels, but not until 24 March 2027, and a house finished as late as March 2028 can still legally be handed over without any. The requirement is new paragraph L3 of Schedule 1 to the Building Regulations 2010, and the array it produces is sized off your ground floor area, not your electricity bill.
The government published the Future Homes and Buildings Standards on 24 March 2026, along with the 2026 edition of Approved Document L. The headline everyone repeated was "solar on all new builds". The document itself is more specific and more useful than that, and if you are buying a new build, or you have just moved into one and the array on the roof looks small, the detail is where your answer is.
The regulation sets a floor, not a target. If your new build came with four panels and a south-facing roof with room for twelve, adding to it is ordinary retrofit work.
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In England, from 24 March 2027. In Wales, from 4 March 2027. Scotland and Northern Ireland run separate building standards and neither carries an equivalent standalone requirement. Both the English and Welsh rules are written as renewable electricity generation rather than solar specifically, but rooftop solar PV is what the guidance is built around.
The English requirement is paragraph L3 of Schedule 1 to the Building Regulations 2010, inserted by the Building Regulations etc. (Amendment) (England) Regulations 2026. Its opening line is short:
"When a building is erected which is or contains one or more dwellings, a system for on-site renewable electricity generation must be installed on the building or within the boundaries of the curtilage of the building."
Two things follow from that wording. The system must be "designed to enable generated electricity to be available for the use of residents of the dwellings", so a developer cannot fit an array that feeds the site office. And "within the boundaries of the curtilage" means it does not have to be on your roof, which matters for the exemptions further down this page.
Wales got there by a different route with almost identical wording. The Building etc. (Amendment) (Wales) Regulations 2026 insert requirement L2A: "When a dwelling or a building containing a dwelling is erected, a system for renewable electricity generation must be installed on-site." Regulation 3, which carries it, comes into force on 4 March 2027.
How big an array does the rule actually buy you?
Enough panels to cover 40 per cent of your ground floor area, at 0.22 kilowatts peak per square metre. That is the benchmark in Approved Document L Volume 1, 2026 edition, paragraph 5.73. The array on your roof has to generate at least as much in a year as a notional array with those characteristics would, and the notional array is assumed to face south-east to south-west, sit at a 45 degree pitch and be unshaded.
Equation 5.1 in the same document puts it as a single multiplication:
PPDWELLING = APVD × EFFPV, where EFFPV is 0.22 kWp per square metre and APVD is an area equivalent to at least 40 per cent of the ground floor area.
The document notes that 0.22 kWp per square metre is the same as "1kWp per 4.5m2". So the sum for a house is: measure the ground floor, take 40 per cent of it, divide by 4.5. Three worked examples. These are illustrative ground floor areas, not averages, so measure your own plan rather than picking the nearest row:
| Ground floor area | Panel area (40%) | Benchmark system size | Roughly |
|---|---|---|---|
| 35 m2 | 14 m2 | 3.08 kWp | 7 panels |
| 45 m2 | 18 m2 | 3.96 kWp | 9 panels |
| 65 m2 | 26 m2 | 5.72 kWp | 13 panels |
Panel counts assume the roughly 2 square metres a standard domestic panel occupies. The Energy Saving Trust puts the typical UK home system at 4.5kWp, so the 45 square metre row lands just under it and the 35 square metre row lands well under. That is the point worth taking away: the rule sizes the array off the footprint of the building, so a compact house gets a small array whatever its occupants plug in.
There is a second route to compliance at 5.73(b), and it is the one that produces the bigger array on a generous roof: an output at least equal to "a photovoltaic array covering the reasonably practicable roof area" at the same 0.22 kWp per square metre. A developer can pick whichever of the two applies. Paragraph 5.76 then says that where neither standard can be met, "efforts should be made to maximise the generation output where it is possible", including specifying higher performance panels, changing panel orientation, and moving roof vents and architectural features to fit more panels in.
The 720 kWh floor, and what it means if you are buying a flat
Paragraph 5.77 sets the level below which a developer can argue the requirement is impossible: an annual output of 720 kWh for a house, or 720 kWh divided by the number of storeys for each dwelling in a block of flats. This is the number nobody quotes and it is the one that decides whether your home gets panels at all.
For a house, 720 kWh a year is modest. Ofgem's Typical Domestic Consumption Values, implemented on 1 July 2026, put a medium single-rate household at 2,500 kWh a year, so the floor is under a third of ordinary use. A developer who can show, following the guidance and Appendix B, that there is not enough roof area to clear 720 kWh has met the exceptional circumstances test.
For flats the division by storeys is severe. In a six storey block the per-dwelling figure is 120 kWh a year, which is under 5 per cent of that same 2,500 kWh household. That is not an oversight, it is arithmetic: one roof shared among six floors of homes cannot do more. But it does mean that if you are buying a flat in a tall block, "the building has solar" and "your flat has meaningful solar" are two different statements, and the second one is worth asking about specifically.
The sizing rules for blocks work through equations 5.2 and 5.3. The building's notional ground floor area is its total floor area divided by the number of storeys, and each flat is then allocated a share in proportion to its own floor area. Paragraph 5.75 allows the generated electricity to serve "individual dwellings and communal spaces where the electricity can be used for the benefit of the residents", so some of the generation may be running lifts and hallway lighting rather than reaching your meter.
When a new build can legally have no panels at all
Requirement L3 carries three exemptions, and the third one is the one buyers do not expect. Taken from the regulation itself, L3 does not apply to a building:
- That is a "relevant building" for the purposes of regulation 7(4) of the Building Regulations 2010, a narrow technical category.
- "On which it is not possible to install a system for on-site renewable electricity generation capable of generating a reasonable output on account of its design or surroundings." This is where the 720 kWh test in paragraph 5.77 does its work. A deeply overshadowed plot or a roof with almost no usable area falls here.
- Where equivalent output is already available from an on-site system somewhere else. The wording allows a system "which is not on the building or within the boundaries of the curtilage of the building", provided it is designed to make the electricity available to residents. In practice that is the route for a shared estate array or a community scheme serving several homes at once. Your roof can be bare and the development still compliant.
If you want to know which of these applied to your house, there is a document that tells you. Paragraph 5.78 says that any array falling short of the benchmarks "will be highlighted in the BREL report", and that evidence for a lower provision has to go to the building control body. Ask the developer for the BREL report. It is produced as a matter of course for building control and it is the only place the shortfall is written down.
Why a home completed in 2028 can still have no solar
Because transitional protection runs a full year past the start date, and it attaches to the paperwork rather than the building. Building Circular 01/2026 sets it out: the changes do not apply where a building notice, an initial notice, or an application for building control approval with full plans was given to the relevant authority before 24 March 2027, provided the work is commenced before 24 March 2028.
Plans for a large site can go in well before any given plot is built out. A plot where the application went in during 2026 and the groundworks started in early 2028 is built to the old standard, legally and with no argument available. Wales mirrors this: its transitional provision protects work commenced before 4 March 2027, or notified before that date and commenced by 3 March 2028.
Higher risk building work, as defined in the regulations, runs six months behind again. Regulations 3, 4, 6, 7, 8 and 9 come into force for that work on 24 September 2027.
So the practical advice for anyone reserving a new build in the next eighteen months is blunt. Do not assume. Ask whether the plot is inside or outside transitional protection, and get the answer before you exchange.
What about Scotland and Northern Ireland?
Neither is covered by these instruments. The English regulations amend the Building Regulations 2010 as they apply in England; the Welsh ones state that they "apply in relation to Wales". Scotland runs its own building standards system, where Section 6 (Energy) of the technical handbooks handles this through a notional building calculation rather than a standalone requirement to install generation, and the April 2026 handbook applies to warrants submitted from 6 April 2026. Northern Ireland has its own technical booklets again.
This is the same pattern that runs through UK solar rules generally. If you are checking anything from planning permission to grant eligibility, the nation you are in changes the answer, and a guide that says "in the UK" without naming one is usually quoting England.
If your new build's array is smaller than your roof
Adding panels to an existing new-build array is ordinary retrofit work. The roof is new and in known condition, the electrical setup is documented, and if the developer fitted in-roof panels the mounting system is already in place.
Three things to check before you get quotes. First, your existing inverter's headroom, because an inverter sized for 4kWp will not simply absorb another 3kWp. Second, your grid connection: the original install will have been notified to your network operator under G98 or G99, and an expansion has to be notified again. Third, whose name the MCS certificate and any Smart Export Guarantee registration sit in, because that decides who is paid for anything the array exports.
On cost, ask installers to price the added capacity separately rather than quoting you a whole new system, and treat the full system cost figures as the ceiling rather than the expectation. Zero rate VAT on the installation applies until 31 March 2027 in Great Britain, after which it reverts to 5 per cent, which the VAT on solar panels page covers in full. And if you want to know what any added capacity is actually worth where you live, the output by postcode zone figures give you the annual kilowatt hours before you talk to anybody.
Tell us your roof and your existing setup and we will pass it to MCS certified installers who quote for expansions as well as fresh installs.
Get My Free Quotes →Frequently asked questions
In England from 24 March 2027 and in Wales from 4 March 2027, yes, though the requirement is worded as on-site renewable electricity generation rather than solar specifically. England's version is paragraph L3 of Schedule 1 to the Building Regulations 2010 and Wales's is requirement L2A. Scotland and Northern Ireland run separate building standards systems and neither carries an equivalent standalone requirement. Three exemptions apply in England, including where equivalent generation is already available to residents from a system elsewhere on the site.
Enough to match a notional array covering 40 per cent of the ground floor area at 0.22 kWp per square metre, which Approved Document L notes is the same as 1kWp per 4.5 square metres. A 45 square metre ground floor gives 18 square metres of panels and a 3.96kWp benchmark, around nine standard panels. A 35 square metre ground floor gives 3.08kWp, around seven. A developer can alternatively meet the standard by covering the reasonably practicable roof area at the same panel efficiency, which on a large simple roof produces more.
Most likely transitional protection. The English requirement only applies where the building notice or full plans application was given on or after 24 March 2027, and even then work notified before that date is protected if it commences before 24 March 2028. Beyond timing, requirement L3 does not apply where the building's design or surroundings make a reasonable output impossible, or where equivalent renewable output is already available to residents from a system elsewhere on the site. The BREL report for your home records any shortfall against the benchmark.
The building does, but each flat's share is small. Approved Document L sizes the array from the building's ground floor area, calculated as total floor area divided by the number of storeys, then allocates a share to each dwelling in proportion to its floor area. The exceptional circumstances threshold at paragraph 5.77 is 720 kWh a year divided by the number of storeys, so in a six storey block it works out at 120 kWh per flat. The guidance also allows the electricity to serve communal spaces, so some of the generation may be powering lifts and hallway lighting rather than reaching your meter.
It is the level below which a developer can demonstrate that installing renewable generation is not possible. Paragraph 5.77 of Approved Document L Volume 1, 2026 edition, describes exceptional circumstances as a dwellinghouse with insufficient roof area to install an array capable of an annual output of 720 kWh, calculated using the approved methodology, or for a block of flats that figure divided by the number of storeys. It is a floor for the impossibility argument, not the target: the actual standard is the 40 per cent of ground floor area benchmark or the reasonably practicable roof area.
Yes, and it is ordinary retrofit work. Check three things first: whether your inverter has capacity for the extra kilowatts, that the expansion is notified to your network operator under G98 or G99 as the original install was, and whose name the MCS certificate and any Smart Export Guarantee registration sit in. Ask for the added capacity to be priced separately rather than as a whole new system. Zero rate VAT applies in Great Britain until 31 March 2027 before reverting to 5 per cent.
The Future Homes and Buildings Standards package covers low carbon heating alongside the new renewable electricity requirement, and the same commencement and transitional dates apply across the whole set: in force 24 March 2027, with protection for work notified before that date and commenced before 24 March 2028, and 24 September 2027 for higher risk building work. The solar requirement, paragraph L3, is separate from the heating provisions and is the only one that mandates on-site generation.
It is the compliance report produced for building control on a new dwelling. Paragraph 5.78 of Approved Document L states that any photovoltaic array not achieving the benchmarks in paragraphs 5.73 and 5.74 will be highlighted in it, and that evidence supporting the reasonably practicable roof area or a lower provision must go to the building control body. If you want to know why your array is the size it is, that report is where the answer was written down, and your developer holds it.