Our client, an NHS Trust, had solar PV systems installed across 10 buildings by a previous contractor. The systems were commissioned between 2021 and 2022 as part of the Trust’s energy efficiency and carbon reduction programme, with the installation costing more than £5 million.
However, multiple systems are experiencing failures. Generation was significantly below predicted output, inverters were showing persistent faults, and the estates team had no visibility of system performance. The original installer was no longer responsive, warranties were at risk of invalidation, and the Trust was left managing failing renewable assets with no technical support.
For the estates directorate, this represented multiple problems: capital investment not delivering expected returns, carbon reduction targets undermined by underperforming systems, potential safety issues on hospital roofs, and reputational risk from a high-profile decarbonisation project failing to deliver.
The Trust needed an independent assessment of what had gone wrong, detailed costings for remediation, and a reliable long-term maintenance partner to ensure the systems delivered their designed 30-year performance.
Multiple buildings were experiencing system failures, and significantly reduced generation. The estates team had no clear understanding of whether issues were isolated or systemic, whether problems were repairable or required complete reinstallation, or what the total remediation cost would be.
Without independent technical expertise, the Trust couldn’t determine whether to pursue the original installer for warranty claims, commission repairs, or write off the investment entirely.
Solar PV systems on NHS buildings must meet stringent safety standards. Fire fighter gateway systems must shut down arrays during emergencies. Electrical installations must comply with healthcare-specific regulations. Roof-mounted equipment must be structurally secure.
With failing systems and an unresponsive installer, the estates team had no confidence that installations met safety requirements or that equipment was properly secured against wind loading and weather exposure.
The Trust had no monitoring capability. Generation data was unavailable. The estates team couldn’t determine whether systems were operating at all, let alone whether they were delivering predicted output. This made carbon reporting impossible and prevented any business case validation for future renewable investments.
Equipment warranties require proper installation to manufacturer specifications. If installations were substandard, warranties would be invalid. The Trust needed documented evidence of installation quality to determine whether warranty claims were viable or whether remediation costs would fall entirely on the estates budget.
Hospital buildings cannot tolerate disruption. Any remediation work would need to be carefully phased around clinical operations, with clear communication to building users and minimal impact on patient care or research activities.
Carbon3 was commissioned to conduct a comprehensive independent inspection of all 10 solar PV systems, provide detailed remediation specifications, and deliver a long-term operations and maintenance contract.
Phase 1: Independent Technical Inspection
Our senior engineer conducted site visits to all 10 buildings, inspecting roof-level installations and electrical infrastructure. Each system was assessed separately with detailed photographic evidence and written reports documenting findings.
The inspection revealed systemic installation failures across 8 of the 10 systems. Issues ranged from minor rectification works to complete non-compliance with manufacturer specifications and safety standards.
Typical findings across multiple sites included:
Structural and safety issues:
- Incorrect ballast placement (systems under-ballasted and at risk of wind uplift)
- Wrong mounting feet placement (not following Van der Valk specifications)
- Insufficient ballast, the panels could be lifted by hand
- Rails digging into roof membrane (roof damage risk)
- Panels installed over guttering and drainage routes
- Systems installed under edge protection (access and safety concerns)
- Missing or damaged wind breakers
Electrical safety issues:
- Live DC voltage at isolators that should have been isolated (electrocution risk)
- DC isolator wires not properly secured (arcing and fire risk)
- Wrong isolators fitted (AC instead of DC, compliance failure)
- Water ingress in junction boxes
- Evidence of water damage and arcing on DC isolators
- Inverters installed in cupboards without clearance (overheating, wires melting)
- No surge protection devices fitted
Installation quality issues:
- Poor cable management throughout (DC strings lying on roofs, in pools of water, pulling on sharp edges)
- MC4 connectors left exposed on roof level, not secured, lying in standing water
- Optimisers not secured, lying loose on roofs
- Cables running through holes drilled in cable trays
- Copex conduit lying on roof with live DC strings inside
- Tray work damaged from people walking on it
- Broken panels
- Missing cable ties, joiners, and securing components
Bird and wildlife issues:
- Heavy bird mess covering panels and reducing output by 15-20%
- Birds nesting under arrays (fire risk and performance degradation)
- Extreme build-up of bird faeces covering MC4 connectors and optimisers
System performance and monitoring issues:
- Fire fighter gateways not working (systems wouldn’t shut down in emergencies)
- Inverters showing multiple fault codes and not producing
- Missing optimisers (up to 70 missing on some strings)
- No generation meters fitted
- No system schematics displayed on site
- No data connection for remote monitoring
- Low insulation resistance readings
Two systems (Academic Centre and Maple Centre) showed significantly fewer issues, suggesting they may have been installed by different contractors or subcontractors.
Phase 2: Remediation Specification and Costing
Following inspection, Carbon3 provided detailed specifications for remediation works required on each system. For 8 of the 10 systems, we recommended complete uplift and reinstallation to manufacturer specifications rather than attempting piecemeal repairs.
Rationale for complete reinstallation:
- Systems installed so far outside manufacturer guidelines that warranty claims would fail
- Safety risks (wind uplift, fire, electrical) too severe for partial fixes
- Cost of comprehensive repairs approaching cost of proper reinstallation
- Opportunity to install correctly once rather than managing ongoing failures
The remediation specification included all materials needed to bring systems to compliance: additional ballast, correct mounting components, proper cable management systems, surge protection devices, generation metering, remote monitoring capability, and full electrical testing and commissioning.
Phase 3: Remediation Delivery
Carbon3 was contracted to remove faulty installations and recommission systems to correct standards. Works will be phased by building to minimise disruption, with clear communication to the estates team and building users throughout.
All remediation works will be completed to manufacturer specifications, with full compliance to NHS technical standards, electrical safety regulations, and building regulations. Each system will receive:
- Correct ballast loading to manufacturer wind loading calculations
- Proper mounting feet placement following Van der Valk guidelines
- Professional cable management with all DC strings secured and protected
- Proper electrical installation with surge protection, correct isolators, and safe routing
- Generation metering for each system
- Remote monitoring capability for performance tracking
- Fire fighter gateway systems tested and operational
- Bird deterrent measures installed
- Full electrical testing and certification
- System schematics displayed at each inverter location
- Full monitoring to provide generation details and flag faults
Phase 4: Ongoing Operations & Maintenance Contract
Following remediation, the Trust contracted Carbon3 for long-term O&M across all 10 systems. The contract includes 24/7 visibility of system performance with automated alerts for faults or underperformance. The estates team has access to a dedicated portal showing real-time generation, historical performance, and carbon savings data for carbon reporting.
Annual site visits to all 10 systems including panel cleaning, inverter testing, electrical safety checks, bird deterrent inspection, and performance optimisation. Issues are identified and resolved before they cause failures.
Priority response to system faults with direct contact to Carbon3’s technical team. Emergency callouts for critical issues (heating failures, safety concerns) with same-day response. Systems are monitored against predicted output. Underperformance is investigated and resolved, ensuring the Trust receives the financial and carbon benefits originally projected. All maintenance activities documented for warranty compliance, insurance requirements, and regulatory inspections. Carbon3 maintains all system records, test certificates, and performance data.
The hospital is now aware of exactly what the faults are with their system, and are proactively working with us on their remediations. Once reinstalled, the systems will generate more energy, and with an ongoing O&M contract, the hospital can feel safe in the knowledge that there won’t be any further issues with the systems, and if there are these will be dealt with at speed.
Our client’s experience demonstrates the importance of installation quality and long-term maintenance for renewable energy systems. Well-designed systems installed poorly will fail. Even properly installed systems require proactive maintenance to deliver 30-year performance.
For estates directors inheriting renewable assets from previous contractors or managing aging installations with uncertain maintenance history, this case study provides a roadmap for recovery and long-term success.
Key Lessons for NHS Estates Teams
Independent inspection protects your interests. When systems underperform and installers are unresponsive, an independent technical assessment provides evidence for warranty claims, insurance claims, or remediation planning. Two non-biased inspections gave our client confidence in their remediation decisions.
Poor installation cannot be patched. When systems are installed fundamentally incorrectly, piecemeal repairs perpetuate problems. Complete reinstallation to correct standards costs more initially but eliminates ongoing failures and delivers reliable long-term performance.
Remote monitoring is non-negotiable. Without visibility of system performance, estates teams cannot identify underperformance, validate business cases, or report carbon savings. Monitoring should be specified from day one, not added after failures occur.
O&M contracts are insurance against failure. Proactive maintenance costs hundreds annually. Reactive repairs cost thousands. System failures cost tens of thousands in lost generation and remediation. Long-term O&M contracts with experienced renewable specialists protect asset value and performance.
NHS environments require specialist contractors. Generic commercial installers often lack understanding of healthcare-specific requirements: infection control, HTM compliance, fire safety scrutiny, operational continuity. Experience working in NHS environments directly correlates with installation quality.
