High-Rise & Low-Rise Flats / Blocks: Solar panels for housing associations

Why flats and blocks offer the easiest, highest-self-consumption solar win

For a housing association, the roof of a low-rise or high-rise block is one of the most efficient places to put solar, because a single array serves the communal landlord supply that runs all day. Lifts, communal lighting, stairwell and corridor heating, water booster pumps and door entry draw power continuously, so generation is consumed on site rather than spilled to export at a lower price. Self-consumption on a communal supply can be high, which is the design position that gives a block array one of the stronger returns in a social-housing portfolio. One roof, many homes served, and a clean separation between the landlord benefit and individual tenant supplies makes the block a natural early win in any decarbonisation programme. It is also one of the simplest benefit models to explain, because the saving lands on the communal account rather than needing a per-dwelling export split negotiated with each household.

There is a practical timing advantage too. Roof access on a block is expensive to arrange, so the cheapest moment to install solar is when the scaffold is already up for something else. Post-Grenfell fire safety work, facade remediation and roof refurbishment all create that access window, and folding a solar array into the same mobilisation removes a large slice of the cost. For an asset manager juggling building safety and decarbonisation on the same buildings, coordinating the two is both cheaper and less disruptive than doing them separately. It also turns a compliance cost the organisation has to bear anyway into an opportunity to add a revenue-generating, bill-reducing asset at the marginal cost of the panels rather than the full cost of access. For an asset manager building a Housing Revenue Account business plan, that reframing of the access cost is often what makes a block array stack up where it might not as a standalone project.

What a typical install looks like and how sizing works

Block systems usually fall in the 10 to 150 kW range on the communal or landlord supply, which is roughly 18 to 275 panels across about 60 to 900 square metres of roof. A system that size generates in the region of 9,000 to 138,000 kWh a year per block and saves somewhere between 2 and 32 tonnes of CO2 annually. Sizing should follow the landlord daytime load. The communal-supply meter data shows the lifts, lighting, pumps and corridor heating, and sizing to that load keeps self-consumption high, rather than oversizing to a number the roof could physically hold. The point of a block array is to displace import on a high, steady daytime baseload, not to maximise export at a low tariff. Communal-supply metering keeps the landlord benefit cleanly separate from individual tenants' own supplies, which matters both for the benefit model and for the grant audit trail. Where resilience, peak-shaving or out-of-hours communal demand make it worthwhile, battery storage can serve the communal load and provide backup, and the case for it should be modelled explicitly rather than assumed.

Costs, payback and tax relief

A block array typically runs £10,000 to £135,000 depending on roof area and access, and high self-consumption keeps the return driven by avoided import rather than low-value export. Because a block roof serves many homes, cost-per-home is efficient even though the absolute project value is larger than a single dwelling. Surplus is registered for the Smart Export Guarantee by the landlord or a tariff partner, and that export income can subsidise the wider programme. Crucially, because the saving lands on the communal supply, it can be passed through to lower service charges, a direct and visible benefit to the residents who pay them. Where solar is delivered as part of concurrent facade or roof works, the shared access can materially improve the economics, and our cost guide works through the per-block numbers including how a battery and shared mobilisation change the payback.

The communal-supply model also answers the objection asset managers raise most often, which is that solar will benefit the landlord rather than the struggling tenant. On a block, the benefit is genuinely shared by design: the array reduces the communal energy cost that residents pay through their service charges, so the saving reaches the people who live in the building rather than disappearing into a landlord export account. That is a cleaner outcome to evidence than a dwelling-level export split, and it is one of the reasons the communal supply is the easiest win to put in front of a board. For capital planning, the block also sits well within a Housing Revenue Account business-plan decarbonisation strand, where the avoided communal energy cost and the SEG income together build a defensible return over the system's twenty-year-plus life. Where the block forms part of a wider programme, it works best when priced alongside the rest of the stock, so the funding stack and the framework call-off cover the communal arrays and the dwelling-level installs together rather than as separate procurements.

Funding routes in detail

Blocks are eligible for the same grant stack as the rest of the stock. The Warm Homes: Social Housing Fund (Wave 3), the successor to the Social Housing Decarbonisation Fund, was allocated £1.29bn in the Autumn Budget 2024 for delivery from 2025 until 2028, and it covers existing social housing below EPC band C in England. Its application window closed on 25 November 2024 and the list of successful landlords was published on 11 March 2025. Delivery runs to September 2028, with all grant to be spent by 31 March 2028 under a mandatory fabric-first, PAS 2035 approach. It sits within the £13.2bn Warm Homes Plan, re-committed at the June 2025 Spending Review across 2025-26 to 2029-30. Where a block's individual flats sit in the lowest EPC bands, ECO4 and ECO4 Flex (running to 31 December 2026) can add funding through the energy-supplier obligation, with ECO4 Flex allowing local-authority referral of fuel-poor and vulnerable households outside standard means-tested criteria. The Smart Export Guarantee then provides ongoing export income on the communal array: tariffs vary by supplier, and the better fixed rates open to anyone are around 12 to 13p per kWh (October 2026, indicative). A funding case for the communal supply is strongest in the format funders expect, with the self-consumption modelling and archetype plans that make it credible and defrayable on time.

Compliance and sector considerations

Blocks bring the building-safety regime into play. For higher-risk buildings of 18m or more, or seven storeys and above, any roof works engage the Building Safety Act 2022 regime, and rooftop arrays should be designed to BS 9991 expectations (fire safety in residential buildings). A roof structural survey is mandatory before any array is loaded onto a block roof, because the additional dead and wind load must be verified against the existing structure. Communal electrical work follows BS 7671, and metering must cleanly separate landlord benefit from tenant supplies so the grant audit trail and the service-charge accounting both hold up. Grid connection is usually a G99 application above 3.68 kW per phase, where DNO timescales can run 6 to 18 months on constrained networks, so the application should go in early and, on a multi-block programme, a portfolio-level conversation with the DNO is worth opening. Rooftop PV on a block of flats is generally permitted development under Class A of Part 14 of the GPDO 2015, within size limits: no more than 0.2 m protrusion, and on a flat roof no more than 0.6 m above the highest part. Listed blocks are excluded, in a conservation area solar is not permitted development on a wall facing a highway and a flat-roof array needs the council’s prior approval, and a local Article 4 direction can remove the right.

How to approach this kind of project

A sound approach starts with the communal-supply meter data and a structural survey, then sizes the array to the landlord daytime load for maximum self-consumption rather than maximum panel count. The G99 grid application should go in early so the DNO clock is running while design is finalised, building-safety requirements should be engaged on higher-risk buildings from the outset, and any concurrent facade or roof works should be coordinated so a single scaffold serves both and the access cost is shared. The landlord should check that any installer is MCS-certified and what warranty cover applies, and the whole call-off can run through a compliant framework such as Fusion21 or Procurement for Housing so procurement stays clean under the Procurement Act 2023. Where a battery improves resilience or self-consumption, it should be modelled explicitly so the trade-off is visible, and the service-charge pass-through should be set out clearly so residents see the benefit on the communal account.

The coordination with building safety is where experienced advice makes the most difference on blocks. Higher-risk buildings carry a regulatory regime that a general solar installer is rarely set up to navigate, and getting the fire design, structural verification and roof access wrong on a block is far more consequential than on a house. The structural survey, the fire design and the building-safety engagement are non-negotiable first steps, not paperwork to be caught up later, and the grid application should be sequenced so the 6 to 18 month DNO timescale on a constrained network does not become the thing that delays the whole programme. On a multi-block portfolio, a single conversation with the DNO about aggregate capacity is better than submitting connection by connection, which can both speed the process and give the network operator a clearer picture of the load being added. The aim is a block that goes from survey to energised without the surprises that stall poorly planned rooftop work on tall buildings.

An illustrative example

Illustrative example (not a client project): a registered provider building a 60-unit regeneration block of affordable and social-rent flats, built to the Future Homes Standard with air-source heat pumps and a fabric-first envelope, might design in a 150 kW rooftop array at design stage to serve the communal supply and landlord systems. Such an array would offset part of the heat-pump and communal load, and designing PV in is generally cheaper than an equivalent retrofit. The figures are illustrative and depend on the block, its communal load, the benefit model and tariff.

If your stock also includes street properties or sheltered schemes, see general needs housing solar and sheltered and supported housing solar. When you are ready, read the cost guide, check the funding routes, send an enquiry, or read the social-housing solar FAQs.