Why did a 318-unit phased scheme need site-specific PV assessment?
A residential developer preparing a two-phase, 318-unit scheme needed to establish a credible and evidence-based approach to solar PV export loads as part of wider infrastructure and grid planning discussions.
Phase 1 comprised 249 units. Phase 2 added a further 69 units. The scheme was residential-led, with Future Homes Standard readiness, solar PV strategy, DNO Point of Connection application support, export load assessment, and infrastructure planning across phased delivery all on the table at the same time.
With Future Homes Standard expectations driving increased adoption of rooftop solar PV, the developer recognised that early assumptions around export capacity could materially affect programme planning, utility coordination, and commercial decisions.
Rather than relying on broad assumptions, the developer wanted a more realistic understanding of likely PV deployment and export demand across the scheme before progressing discussions with the DNO.
What challenge did Future Homes Standard create for this masterplan?
The developer faced a growing industry challenge: translating Future Homes Standard expectations into practical, site-specific infrastructure assumptions.
Industry guidance and emerging expectations around solar PV provision, often interpreted as approximately 40% equivalent roof coverage relative to ground floor area, created pressure to demonstrate future-ready energy strategies. Approved Document L (2026), which takes effect from 24 March 2027, sets out statutory guidance for Requirement L3 and the provision of on-site renewable electricity generation on new dwellings.
However, applying this expectation across a live residential masterplan was far from straightforward. The complexity was not simply the headline percentage.
Across the scheme, individual plots and buildings varied significantly in roof orientation, available roof area, shading considerations, roof geometry and usable mounting zones, plot typologies, and physical and planning constraints.
Some properties could accommodate larger PV arrays than baseline assumptions suggested. Others could not reasonably achieve equivalent provision without disproportionate design compromise or impractical layouts.
The developer needed to understand what a realistic PV deployment scenario actually looked like across both phases, and what that meant for export loads, infrastructure planning, and future grid engagement. At the same time, they needed a defensible basis for identifying where full provision may not be practical and where evidence-based exceptions could be justified.
Why were standard export assumptions not enough?
Early-stage infrastructure planning often relies on high-level assumptions for generation and export loads. For conventional developments, this can be sufficient.
But Future Homes Standard considerations are changing the level of scrutiny required. The Future Homes Hub guide on grid connections for all-electric houses explains that new homes add significant import and export loads when aggregated across a development, and that accurate load assessment is key to securing a connection as quickly and cost-effectively as possible.
Applying a simple percentage assumption uniformly across a development risked creating several problems:
- Overstating likely export capacity in some areas
- Underestimating potential generation in others
- Introducing uncertainty into PoC discussions
- Increasing the risk of later-stage infrastructure revisions
- Reducing confidence in programme and cost planning
The developer understood that a generic assumption would not reflect how rooftop PV would actually be delivered across the scheme. Nor would treating total installed PV capacity as a proxy for export. Generation varies by roof orientation, shading, and typology, and scheme-level export depends on how those outputs combine hour by hour across hundreds of homes and two delivery phases. Nameplate kWp summed across the masterplan overstates what is actually installed, synchronised, and available to export at any given time.
A more detailed assessment was needed, one that considered the practical realities of the development layout and translated those realities into a more credible export load position.
How did HubbPro help the developer?
HubbPro worked alongside the developer as a technical guide, helping the project team move from broad assumptions to a more structured and evidence-based understanding of likely PV deployment across the site.
Rather than treating the development as a uniform load profile, HubbPro assessed the scheme at a more practical level, considering:
- Building typologies
- Roof orientation and geometry
- Usable roof space
- Physical constraints affecting PV placement
- Variations between plots and phases
- Areas where enhanced provision was achievable
- Areas where full provision was unlikely to be practical
That plot-level assessment established how much PV was realistically achievable on each building type. The next step was to understand what that generation meant for export.
HubbPro simulated dwelling energy performance throughout the course of a year, modelling heat pump load, baseline electrical demand, and other in-home consumption hour by hour. Solar generation was simulated on the same hourly basis, using roof orientation, usable area, and shading for each typology.
Combining those two simulations produced an annual hourly energy profile for each scenario. At any given hour, the model showed whether the dwelling was importing from the grid, consuming its own generation, or exporting surplus. Summing net export across the year, and then aggregating across plot types and phases, gave a much clearer picture of likely export load than nameplate PV capacity alone.
This mattered at scheme level. Individual homes generate at different times and at different levels depending on roof geometry and orientation. Aggregating hourly profiles across 318 units and two phases captured that variation and produced a more credible coincident export position than an approach based on installed kWp alone.
Importantly, the process also helped identify where exceptions may need to be justified due to genuine site or building constraints, creating a clearer technical narrative to support wider planning and infrastructure discussions.
The resulting position provided the developer with more informed data to support DNO Point of Connection engagement, infrastructure sizing considerations, utility coordination, commercial planning, and programme decision-making across both phases.
HubbPro did not replace the developer's decision-making process. Instead, it provided the technical clarity needed for the developer to move forward with greater confidence and a stronger evidence base.
What outcomes did the developer gain?
By developing a more realistic export load assessment, the developer was able to approach infrastructure planning with improved clarity and reduced uncertainty.
Clearer PV export load assumptions
The project team gained a more credible understanding of likely generation and export profiles across the scheme. Annual hourly energy modelling captured variation in PV output and coincident export, avoiding reliance on nameplate PV capacity or broad averages.
Better-informed DNO PoC discussions
The developer was able to engage with grid stakeholders using a more robust technical position grounded in the actual characteristics of the development.
Reduced risk of late-stage surprises
Early visibility of likely export scenarios helped reduce the risk of future infrastructure revisions or unexpected grid-related constraints emerging later in the programme.
Evidence to support practical exceptions
Where full PV provision was not realistically achievable, the developer had a clearer technical rationale supported by site-specific assessment.
Improved infrastructure strategy
A more accurate view of likely generation demand helped support wider infrastructure coordination and phased delivery planning.
Greater confidence across both phases
The developer could progress Phase 1 and Phase 2 planning with stronger technical alignment between sustainability objectives, site realities, and utility considerations.
What can other developers learn from this project?
As Future Homes Standard expectations evolve, developers are increasingly being asked to balance sustainability ambitions with practical delivery constraints.
The key lesson from this project was not that every plot should achieve identical PV provision. It was that infrastructure planning becomes more effective when assumptions reflect how developments will actually be built.
For residential developers, that means:
- Testing assumptions early
- Understanding site-specific constraints
- Modelling export from annual hourly energy profiles, not nameplate capacity alone
- Assessing realistic PV deployment scenarios
- Engaging with grid considerations before they become programme risks
- Building evidence for justified exceptions where required
Developers who take this approach are often better positioned to make informed commercial and infrastructure decisions as projects progress.
How can HubbPro help before uncertainty becomes programme risk?
Future Homes Standard requirements are increasing the importance of early-stage energy and infrastructure planning.
HubbPro helps developers build practical, evidence-based strategies around solar PV, export loads, and infrastructure readiness, supporting clearer DNO engagement and more confident decision-making across residential schemes.
If you are assessing grid implications, PV strategy, or PoC requirements on an upcoming development, HubbPro can help you establish a more realistic technical position before uncertainty becomes programme risk.