TL;DR From 24 March 2027, every new home in England must have solar PV under the Future Homes Standard in accordance with the final Approved Documents. It is a functional requirement of Building Regulations, not an optional upgrade.
For developers, solar now has to be designed in from day one and sized against ground floor area. For new build buyers, a compliance-minimum system and a properly designed one will produce very different bills over the next 25 years.
This article covers what has changed, what it means for developers, what it means for buyers, and how to make sure a new build solar system is actually worth the roof it sits on.
The Future Homes Standard is the 2026 update to Part L of the Building Regulations for England. It requires new homes to produce at least 75% fewer carbon emissions than homes built to the 2013 regulations. In practice, that means three things: heat pumps become the default heating system, fabric performance is pushed harder on airtightness, and solar PV becomes a legal requirement on almost every new dwelling.
The headline dates are worth knowing:
The Approved Documents were published on 24 March 2026. The regulations come into force on 24 March 2027. A 12-month transition period runs until 24 March 2028 for projects already in the pipeline. Gas boilers cannot meet the new carbon targets and are effectively out. Assessment is initially via SAP 10.3, with the Home Energy Model (HEM) replacing it further down the line.
If you are a developer with a site hitting detailed design in 2026, you are already building under the new standard.
Yes. Requirement L3, introduced in the March 2026 amendment to the Building Regulations, makes on-site renewable electricity generation a standalone functional requirement. For most new homes this means rooftop solar PV covering an area equivalent to 40% of the dwelling's ground floor area.
The 40% rule is the default. Exemptions exist, for example where roof orientation or shading makes it unworkable, for buildings over 15 storeys, and where the installer can technically justify a reduced array. But solar PV is described in the regulations as a non-tradeable element. You cannot simply beef up the insulation and skip the panels. It has to be delivered unless a genuine constraint can be evidenced.
For most detached and semi-detached homes, the 40% rule lands at around a 3 to 4 kWp system. For terraces and flats, the calculation can produce smaller arrays, though design teams are increasingly specifying larger systems where the roof allows, because it improves the house's running costs and its saleability.
The temptation on a new build project is to treat solar as a late-stage line item, something the M&E contractor sorts out once the building envelope is agreed. Under the Future Homes Standard that approach will cost you, in three ways.
Roof design drives solar yield. Orientation, pitch, shading from neighbouring plots, dormers, chimneys, and rooflights all shape how much usable generation a roof can produce. If the architect sets the roof first and the installer is asked to fit panels to what is left, you almost always end up with a compliant-but-unimpressive system. Spirit Energy's design team works with architects and housebuilders at concept stage to resolve these issues before drawings are finalised. That typically adds around 20 to 30% more annual generation on the same roof area.
Electrical first fix is cheaper than retrofit. Running cables, setting aside riser space, and pre-specifying consumer unit capacity during first fix adds hours to an electrician's job. Going back in later adds days and involves chasing out finished walls. The saving from integrating early is significant, and it compounds across a large site.
Compliance modelling feeds back into design. The SAP or HEM assessor needs to know the PV kWp, the orientation, the tilt, the shading factor, and for HEM, how self-consumption is likely to behave through the year.
The commercial reality for a housebuilder is that solar has gone from a cost line to a specification battle. Every new home in England from 2027 will have it. The question is whether yours is better than your competitor's two streets away.
Buyers in 2026 and beyond are walking into show homes with energy bills in mind in a way they simply were not ten years ago. Recent research from the property sector consistently shows that homes with meaningful on-site generation and battery storage command a premium over equivalent properties without. The effect is strongest where the system is properly sized and well documented, because buyers and their mortgage advisers can see the expected annual savings and the EPC uplift.
A minimum-compliance 3 kWp array on a south-facing roof generates roughly 2,700 kWh per year. A 6 kWp system on the same house, where the roof allows, more than doubles the generation and transforms the running cost profile. The incremental cost to a developer of going from a 3 kWp system to a 6 kWp system is modest. The incremental impact on buyer perception is not.
For commercial developers, the calculation is different but no less pressing. Large warehouses, data centres, care homes, and hotels have acres of underused roof space that can now anchor a tenant's own ESG reporting. Institutional tenants increasingly require buildings that help them meet corporate net zero targets. Buildings that come with on-site generation and, increasingly, EV charging infrastructure powered directly from that generation, let in tenants who would otherwise walk.
The hidden cost of the Future Homes Standard is non-compliance. A SAP or HEM assessment that fails at sign-off stage, because the solar array as installed does not match the as-designed specification, delays occupation, delays sales, and creates a paper trail of risk that affects warranty and insurance.
If you are buying a new build that completes after 24 March 2027, your home will come with solar as standard. That is the new baseline. What varies, and what is worth asking about, is how well the solar has been designed.
A well-specified system on an average four-bedroom new build, with a heat pump and typical household electricity use of around 8,000 to 10,000 kWh per year, can cover 30 to 45% of annual consumption directly from solar. Pair that with a battery and a sensible off-peak tariff strategy, and the number climbs well past 60%.
What did £17k on solar system give our customer Sam? Read here.
Most Future Homes Standard systems will be fitted with solar only at first, to meet the 40% rule. A battery is not mandatory. But the value of solar to the homeowner increases dramatically when storage is added, because it lets you use the energy you generate in the daytime to cover evening consumption, when grid electricity is most expensive. If you are buying a new build and the developer has not thought about battery-ready design, that is a reasonable question to raise.
Solar panels are warrantied for 25 years. The systems Spirit Energy installed in 2010 are still generating today. When you move into a Future Homes Standard new build, you are not just paying for a house with solar on it. You are locking in the cost of a meaningful slice of your electricity at today's prices for the next quarter-century. There is no UK energy supplier offering a 25-year fixed-rate tariff. This is the closest thing to it.
Spirit Energy has been designing and installing solar since 2010. We have completed over 7,000 installations across residential, commercial, and new build projects. We are MCS certified, a certified Tesla Powerwall installer with one of the longest track records in the UK, including the first Powerwall 3 installation in the country, and we are a multi-award-winning family business with design, engineering, and installation under one roof.
For property developers we offer:
Full design and feasibility support from concept stage, including compliance modelling input for SAP 10.3 and HEM. Direct liaison with architects, M&E consultants, and site managers, so the solar integrates with the rest of the build rather than fighting it. Scalable installation capacity for volume housing schemes, bespoke high-end residential, and commercial developments. A single point of contact through the lifecycle of the project, from tender to aftercare. Ongoing servicing and monitoring agreements for the life of the asset, so the compliance claim you made at handover holds up year after year.
For new build buyers living in homes we have specified, you get a system designed to actually perform, not a 40% minimum ticked off on a drawing.
If you are a property developer working on a scheme that will be built under the Future Homes Standard, get in touch for a free, bespoke design and feasibility study. We will model the array against the 40% rule, advise on the compliance route, and produce quotations that your tender team or development director can actually use.
Call us on 0118 951 4490, email info@spiritenergy.co.uk, or request a quote through the form on our website.
The regulations come into force on 24 March 2027. A 12-month transition period runs until 24 March 2028 for projects already in progress. The Approved Documents were published on 24 March 2026, so any scheme entering detailed design now is being built under the new standard in practice.
The default requirement is an array equivalent to 40% of the dwelling's ground floor area. For most detached and semi-detached homes that works out at around 3 to 4 kWp. Larger systems are often better value per panel and improve the home's running costs significantly.
Only where there is a documented technical constraint. Shading, unfavourable orientation, structural issues, or buildings over 15 storeys can qualify for reduced arrays, but the exemption has to be evidenced. Solar is described in the regulations as non-tradeable with other fabric measures.
The regulations do not use the word "banned", but the carbon targets are set at a level that gas and oil boilers cannot meet. In practice, heat pumps and connections to heat networks will be the only compliant heating options for almost all new homes.
No, not currently. Solar PV is the mandated element. Batteries remain optional, although many developers are specifying battery-ready infrastructure so buyers can add storage later without a full retrofit.
Part L 2026 applies to non-domestic buildings as well, with the rules coming into force from 24 March 2027 for non-high-risk buildings and 24 September 2027 for high-risk buildings. Commercial new builds will also need solar PV and low-carbon heating.
An MCS-certified installer with experience in SAP 10.3 or HEM modelling, in-house design capability, and a track record in residential or commercial new builds. Spirit Energy offers all of the above and works with developers from concept stage to handover.