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300 kWp + 250 kWh NHS Hospital Solar & Battery Project

Project snapshot: 300 kWp rooftop PV and 250 kWh LFP BESS at Birmingham City Hospital NHS Trust

Bee Solar delivered a 300 kWp rooftop array paired with a 250 kWh lithium iron phosphate (LFP) battery storage system for Birmingham City Hospital NHS Trust, Birmingham, West Midlands, completed in 2024. This acute NHS hospital solar and battery project demonstrates that high-capacity PV and storage can be engineered successfully on a constrained clinical site without compromising safety standards. The project arrives at a time when the wider case for commercial solar in 2025 is being reinforced by rising energy costs and net-zero targets across the public sector.

This was not an empty-roof installation. The array had to be designed around chiller plant, exhaust ventilation, and fire evacuation routes. Bee Solar is the Manchester-based installer for this project; the delivery model covers Birmingham and the North West. This page is a delivery case study, not a government funding announcement, and it makes no claim of energy independence: the trust's generators remain part of the resilience picture throughout. National NHS and Great British Energy solar programmes exist, but this page focuses on what was physically delivered on one acute site.

The challenge: dense acute roofs, clinical electrical safety, and HTM 06-01

The estates team at Birmingham City Hospital needed measurable cost savings without any risk to patient safety or HTM 06-01 compliance. HTM 06-01 is the design standard for electrical services in UK health sector buildings. It governs how power systems must behave around life-safety loads, and it operates as a veto criterion: any installation that risks clinical electrical safety cannot proceed regardless of the financial case. Trusts that skip this gate expose themselves to clinical risk and governance failure, which is why the standard filters out most standard commercial solar approaches before they reach the survey stage. This site’s 24/7 demand profile and dense roof structure illustrate exactly why hospital buildings suit large-scale PV, but only when the design respects these constraints.

The roof was the first obstacle. It was densely occupied with chiller plant, exhaust ventilation, and fire evacuation routes, so this was never a case of covering an empty surface with panels. The demand profile made the stakes clear: with over £950,000 spent on electricity each year and 62% of that load coming from HVAC and medical equipment, any disruption or backfeed risk would directly threaten clinical operations. HVAC and medical loads are not deferrable; a chiller failure or an equipment outage during a procedure has immediate patient consequences.

For NHS Trust estates managers and healthcare facility directors, the concerns are specific:

Generic commercial installers who treat a hospital like a warehouse roof will fail on HTM 06-01. It is not a badge to be collected, it is a design gate that filters out most standard commercial solar approaches before they reach the survey stage. The trusts that get this wrong discover the gap between a general commercial install and a clinical-grade design only after procurement has started.

The solution: LiDAR drone survey, 3D CAD layout, and elevated frames that recovered 68% usable roof

Bee Solar conducted a LiDAR drone survey and produced a 3D CAD layout that recovered 68% usable roof area at Birmingham City Hospital. Without this survey-first method, the obvious conclusion would have been that the roof had no space for a 300 kWp array.

The method worked in sequence:

  1. LiDAR drone survey: The occupied roof was mapped in three dimensions, capturing every plant obstruction, exhaust outlet, and walkway with centimetre-level accuracy. LiDAR measures distance with laser pulses, producing a precise point cloud of the roof surface and everything on it, which standard photography cannot provide. Unlike a visual drone inspection, LiDAR penetrates the full geometry of the roof, so the design team knows exactly where a chiller housing ends and where a walkway begins before a single panel is specified.
  2. 3D CAD layout: The survey data was converted into a detailed CAD model of the roof, allowing the design team to place the array around existing plant rather than assuming a clear surface. Every obstacle in the CAD model is a real, measured obstruction, which means the layout can be validated against fire routes and plant access requirements before any equipment is ordered.
  3. Elevated mounting frames: Where chiller plant occupied prime south-facing roof area, elevated mounting structures were designed to raise panels above the chillers, recovering usable area that a ground-level or standard tilt frame layout would have lost. This is the step that recovered the largest share of otherwise unusable roof. The elevated frames maintain airflow and maintenance access beneath the array while capturing solar gain that would otherwise be lost to plant footprints.
  4. Fire route preservation: All fire evacuation walkways were preserved as design inputs, not afterthoughts. The layout was cycled until plant clearance and walkway access were both maintained. Fire routes on acute hospital roofs are not cosmetic; they are part of the building's life-safety strategy, and blocking one is a compliance failure.

The resulting system paired a 300 kWp array with a 250 kWh LFP battery, sized to the site's load profile rather than to a generic template. LFP chemistry was selected for its thermal stability and cycle life, which matter on a site where the battery is cycled daily for peak shaving while holding a reserve for emergencies. The specific engineering choices here, from the survey to the frames, are a direct application of our commercial installation process on a complex live site.

The common mistake on constrained hospital roofs is designing as if the roof were empty. That approach either produces an undersized array or, worse, a layout that blocks plant access or fire walkways. The LiDAR and CAD method removes that risk before any equipment is ordered, which is why the 68% recovery figure matters: it is the difference between a viable business case and a project that never leaves the feasibility stage.

HTM 06-01-compliant electrical design and independent consultant review

All designs for this project were reviewed by an independent electrical consultant and were fully compliant with HTM 06-01. The independent review is what separates a compliant design from a claimed one.

HTM 06-01 is the NHS's design standard for electrical services, covering safety of life, continuity of service, and the protection of clinical loads. In practice it means:

The independent review is the proof point that matters for estates boards. A contractor can claim compliance, but a third-party electrical consultant reviewing the design against HTM 06-01 provides the audit trail that trust governance requires. This project's solar and battery system complements the hospital's generators; it does not replace them. The EMS (energy management system) acts as the control layer that enables reserve isolation, covered in the next section. For estates teams, the operational takeaway is straightforward: solar and battery sit downstream of the hospital's existing resilience hierarchy, not above it.

Battery duty cycle: 45% emergency reserve vs 55% peak shaving

The EMS isolates 45% of the 250 kWh LFP battery capacity for emergency backup while cycling the remaining 55% for daily peak shaving. This split is the design decision that makes the battery both a resilience asset and a commercial asset on the same site. The mechanics of this setup are a practical example of how commercial battery storage works in a high-reliability environment.

The battery performs three distinct duties:

  1. Emergency reserve (45%): This portion is isolated by the EMS and held in reserve for critical-load backup. It is not cycled for daily economics, so it remains available when a grid outage occurs. Cycling this reserve for bill savings would leave the hospital exposed during an actual emergency. The EMS enforces this isolation in software, so the reserve cannot be accidentally drawn down by the peak-shaving cycle.
  2. Peak shaving (55%): The remaining capacity is cycled daily to discharge during peak demand periods, reducing the demand charges that form a significant part of the hospital's electricity bill. For a 650-bed acute trust spending over £950,000 annually, peak demand charges are a material cost, and a 38% reduction in those charges is a direct cashflow improvement.
  3. Generator complement: The battery supports the resilience picture but does not replace generators. The measured result is that generator test-run frequency reduced from weekly to monthly, which cuts fuel, maintenance, and staff time while keeping the generators available for full outages. The generators are still tested, still maintained, and still capable of carrying the full essential load; they simply do not need weekly exercise runs because the battery covers short-duration gaps.

The 45/55 split is the critical design decision. A battery cycled entirely for commercial gain offers no resilience value. A battery held entirely in reserve offers no payback. The split is set by the EMS based on the hospital's critical-load profile and peak demand pattern. There is no universal ratio that fits every trust; the split must be calculated from the site's own load data, which is exactly why the survey-first process matters before a battery size is committed.

Results: £92,000 bill reduction, 98 t CO2e, 4.2-hour backup, and Salix cashflow

Annual electricity bill reduced by £92,000, a 10% reduction in total consumption. Carbon footprint reduced by 98 tonnes CO2e annually. These figures are specific to this Birmingham City Hospital project and are not industry averages.

Metric Result
Annual bill reduction £92,000 (10% of total consumption)
Daytime demand offset 55% (not total independence)
Peak demand charges Cut by 38% through battery discharge
Critical load backup Extended to 4.2 hours during grid test outage
Generator test frequency Reduced from weekly to monthly
Carbon reduction 98 tonnes CO2e annually
Funding Salix Finance, savings exceeded repayments from month one

The 55% daytime offset is a measured figure, not a claim of energy independence. The hospital still imports electricity at night and during periods of low solar generation. The 4.2-hour backup figure came from an actual grid test outage, providing evidence that the reserve isolation works under real conditions rather than in simulation. That test outage is the difference between a theoretical backup claim and a demonstrated one.

The Salix Finance arrangement was structured so that savings exceeded repayments from the first month. For trusts where capital is constrained, the results achieved here highlight how alternative funding routes like a zero-capex solar PPA could also be explored. No interest rates, eligibility terms, or repayment periods are claimed here beyond what the project data confirms. For NHS estates teams, the cashflow point is decisive: the project did not require a net budget increase in year one, because the energy savings covered the finance repayments and generated a surplus immediately. The combination of bill reduction, peak demand savings, and carbon reduction supports the trust's net-zero decarbonisation pathway with measured numbers that can go into board papers. The 98 t CO2e annual reduction is a verified output of this site, not a projection from a generic savings calculator.

Commissioning a hospital-grade survey from Bee Solar (Manchester)

Every project starts with a free site survey. Bee Solar, based in Manchester, Greater Manchester, delivers surveys, quotations, delivery stages, and aftercare for healthcare and commercial estates across the North West and beyond. Call 0161 570 0596 or use the Start Your Project enquiry to begin.

The process for a constrained estate follows the same survey-first discipline used at Birmingham City Hospital:

  1. Site survey: LiDAR drone survey where roofs are cluttered or difficult to access, with 3D CAD layout to map plant, walkways, and usable area
  2. HTM-aware design: For healthcare sites, all electrical designs are reviewed against HTM 06-01 before installation begins
  3. Disruption planning: Installation sequencing on a live site, with plant access and clinical operations maintained throughout
  4. Aftercare: Ongoing system monitoring and maintenance from the Manchester base

The same survey-first process applies whether the site is an acute trust in the West Midlands, a community hospital in the North West, or a commercial estate with similar roof constraints. Clients can review the feasibility and energy audit process on a comparable commercial project. The Birmingham project is proof of delivery at acute-hospital scale; the survey method is transferable to any site with occupied roofs and compliance requirements.

Related services include Solar Batteries. Related projects in different sectors demonstrate regional capability without being conflated with this NHS case:

The Birmingham City Hospital project was delivered by Bee Solar from Manchester. For sites with similar high-demand, high-resilience requirements, we have delivered a data centre solar and battery project and offer solar solutions for data centres. If your trust or estate needs a survey-first approach with HTM 06-01 awareness, the process starts with that free survey and a conversation about your roof constraints, load profile, and funding options. The earlier in the feasibility stage that survey happens, the more options the design team has to work around plant, preserve fire routes, and size the battery to your actual load data.

Frequently Asked Questions

Can rooftop solar and battery storage be installed on an acute NHS hospital without breaching HTM 06-01?

Yes. Rooftop solar and battery storage can be installed on an acute NHS hospital without breaching HTM 06-01, provided the design is reviewed against the standard and a qualified electrical consultant provides independent verification. At Birmingham City Hospital, all designs were independently reviewed and fully compliant. HTM 06-01 governs how electrical systems interact with life-safety loads, so the key requirements are proper isolation, no backfeed into clinical circuits, and no claim of full islanding. Generators and UPS systems remain the primary resilience layer.

How did LiDAR drone survey and 3D CAD recover usable roof area around hospital plant and fire routes?

LiDAR drone survey mapped the occupied roof in three dimensions, capturing chiller plant, exhaust ventilation, and walkway positions with laser precision. The 3D CAD layout then placed panels around those obstructions, with elevated mounting frames lifting panels above chiller plant where necessary. This method recovered 68% usable roof area at Birmingham City Hospital while preserving all fire evacuation walkways and plant clearance. Without the elevated frames, that area above the chillers would have been lost to the array entirely.

How should hospital BESS capacity be split between emergency reserve and peak shaving?

A hospital battery should split capacity between emergency reserve and peak shaving using an EMS-controlled duty cycle, with the reserve isolated from daily cycling. At Birmingham City Hospital, the EMS isolates 45% of the 250 kWh capacity for emergency backup and cycles 55% for daily peak shaving. The reserve portion is never cycled for commercial gain, ensuring it remains available during grid outages. The ratio should be calculated from the site's own critical-load profile and peak demand pattern rather than copied from another project.

Do solar batteries replace hospital generators or UPS, or do they complement them?

Solar batteries complement hospital generators and UPS systems; they do not replace them. The Birmingham City Hospital project demonstrated this by reducing generator test-run frequency from weekly to monthly, proving the battery supports the resilience picture without becoming the primary backup. Generators remain the essential standby for full outages, and UPS systems continue to cover the gap between power loss and generator start. The battery adds short-duration cover and reduces the operational burden on the generators, but it does not remove the need for them.

How much did this NHS hospital solar and battery project cut electricity bills and CO2e?

This project cut the annual electricity bill by £92,000, a 10% reduction in total consumption, and reduced carbon emissions by 98 tonnes CO2e annually. The system also offset 55% of daytime electricity demand and cut peak demand charges by 38% through battery discharge. These figures are specific to Birmingham City Hospital NHS Trust and should not be treated as industry averages or applied to other sites without a fresh survey and load analysis.

How did Salix Finance affect cashflow on this 300 kWp / 250 kWh project?

Salix Finance funded the project with savings exceeding repayments from month one. This structure means the trust's cashflow was positive from the first payment period, with energy bill savings covering the finance repayments and generating a net surplus. No interest rates or repayment terms are claimed beyond what the project data confirms. For estates teams building a board-level business case, the month-one positive cashflow is the figure that removes the funding objection.

Can a Manchester-based installer deliver NHS-scale PV and BESS (including a West Midlands acute site)?

Yes. Bee Solar, based in Manchester, delivered the 300 kWp / 250 kWh system at Birmingham City Hospital in the West Midlands, completed in 2024. Delivery covered the full process: LiDAR survey, 3D CAD design, HTM 06-01-compliant electrical engineering, installation, and aftercare. The same survey-first process applies to NHS and commercial estates across the North West and wider service area, with the Manchester base providing ongoing monitoring and maintenance after commissioning.