The four insurance layers
Office solar installations interact with four distinct insurance regimes. Understanding each is essential before install commences.
1. Existing building insurance
The building’s existing insurance policy needs to be informed of the install. Typically the building insurer issues an endorsement to cover the PV asset, sometimes at a small premium uplift (£500-£3,000 on a £150-£500k building policy is typical).
Key points:
- Notification timing. Inform insurer at design stage, not after install. Late notification can void cover.
- Roof penetration risk. If install uses ballasted (penetration-free) mounting, premium uplift is minimal. Penetration-based mounting may require structural engineering certification.
- Fire risk. PV systems do not materially increase fire risk on modern installations (lithium-ion battery storage does — covered separately).
- Theft. Solar panels are difficult to remove and have low resale value, so theft is rare. Insurers reflect this.
2. New PV-specific insurance
The PV asset itself can be insured separately or under the building policy. Common arrangements:
- Combined cover under building insurance (typical for systems <500 kWp): single policy, single premium, single claim point.
- Standalone solar insurance (typical for systems >500 kWp): specialist PV insurers (HSB Engineering, Munich Re, Allianz Specialty) provide dedicated cover including weather damage, theft, electrical fault.
- Module/inverter warranty insurance: can be wrapped into the IWA (Insurance-Backed Warranty) or purchased separately.
3. Public and product liability
The installer carries public liability (typically £5-10m cover) during install and product liability (typically £2-5m) post-install. Customer-side liability for third-party injury from PV equipment is usually covered by existing public liability insurance (no specific PV uplift needed).
4. Business interruption
Solar PV can affect business interruption insurance in two ways:
- Reduced BI for power outages. A PV system with battery storage provides resilience during grid outages, potentially reducing BI losses. Some insurers discount BI premium for resilience-equipped sites.
- BI extension for install-period disruption. If the install causes any temporary disruption (rare but possible), existing BI cover should extend to cover install-period delays. Confirm with insurer.
Specific risks and how to manage them
Hail damage. Modern PV modules are tested to IEC 61215 hailstone impact (25mm hailstones at 23 m/s). UK climate rarely sees hail above this threshold, but coastal and eastern England (particularly Lincolnshire, Norfolk, Suffolk, Sussex) have higher hail risk. Insurance covers but premium can be marginally higher.
Wind damage. Modern mounting systems are designed to BS EN 1991-1-4 wind loads — typically certified to 32-40 m/s wind speeds. UK extreme weather events occasionally exceed this in coastal locations. Insurance covers but install location affects premium.
Lightning damage. PV systems are typically protected by surge protection devices at module, string, and main panel level. Direct lightning strike damage is rare but covered by standard policy.
Snow load. Roof snow loading is calculated to BS EN 1991-1-3. UK snow loads vary by altitude and location — Scottish highland sites need higher structural capacity than London city centres.
Roof leak attribution. If a roof develops a leak post-PV-install, the question becomes whether the leak relates to the install. Modern ballasted mounting eliminates this risk; penetration-based mounting requires careful documentation of pre-install roof condition.
Battery storage insurance
Battery storage adds specific insurance considerations:
- Fire risk. Lithium-ion batteries (predominantly LFP in 2026 commercial use) have low but non-zero fire risk. UK insurers typically require BS EN 62619 or BS EN 62933-5 compliant systems plus appropriate fire suppression (Novec 1230, aerosol systems).
- Storage location. Outdoor enclosures (typical for >200 kWh systems) require lower fire risk premium than indoor storage. Indoor storage requires fire-rated compartmentation.
- Module-level monitoring. Insurers increasingly require battery management system (BMS) data sharing for fault detection and incident response.
Battery storage insurance is typically a £1,500-£8,000/year addition to building insurance depending on system size and location.
What we recommend
For office solar projects, standard insurance arrangement:
- Inform existing building insurer at proposal stage. Confirm policy extension and any premium uplift.
- For systems >500 kWp, consider specialist PV cover. Typically wraps in better claims experience for large PV-specific events.
- Battery storage: confirm insurer fire suppression requirements. Build to those specs at install.
- IWA covers installer risk. Our standard 10-year IWA via QANW protects against our business failure scenarios.
- Annual policy review. As PV market matures, premiums have been trending down. Annual market check usually delivers savings.
We provide insurer-ready documentation packs (electrical certificates, structural certificates, fire risk assessment, BMS specifications) as part of commissioning handover.
Request a feasibility study with full insurance documentation considerations.
All-risks vs business interruption cover: what each protects
The insurance framework for commercial solar is broader than most building managers realise. Two distinct types of cover apply.
All-risks (material damage) cover protects the physical assets — the solar panels, inverters, mounting structure, cabling, and switchgear — against physical loss or damage from any cause not specifically excluded. All-risks is typically included within or endorsed onto the building’s existing property insurance policy for systems under 500 kWp.
What all-risks covers on a commercial solar installation:
- Storm damage (wind, hail, snow loading beyond design parameters)
- Fire damage (including from adjacent building fires)
- Lightning strike direct damage
- Vandalism and malicious damage
- Accidental damage during roof maintenance operations
- Theft (rare due to low resale value, but covered)
- Subsidence (where separate from pre-existing condition)
What all-risks typically excludes:
- Gradual deterioration (normal weathering, panel degradation within specification)
- Manufacturing defects (this is a manufacturer warranty claim, not an insurance claim)
- Deliberate damage by the insured
- Electrical/mechanical breakdown of inverters (usually covered by inverter warranty or specialist machinery breakdown cover, not property all-risks)
- Consequential loss (loss of electricity savings from system outage — this falls to Business Interruption cover)
Business Interruption (BI) cover for solar. Standard BI insurance covers loss of profit following physical damage to the insured’s property. For an office building where the PV system is a significant energy asset, BI cover can be extended to include:
- Loss of electricity savings from solar outage following an insured event (fire, storm damage, etc.)
- Additional electricity costs during system repair/replacement period
- Contract penalties incurred from inability to supply electricity under PPA (where applicable)
BI extension for solar PV income/savings is available from specialist brokers but is not automatic on standard commercial BI policies. It must be explicitly requested and is typically rated on the annual electricity value at risk.
Worked example: A 400 kWp office system generating 368,000 kWh/year saving 110,400/year (at 30p/kWh) has an annualised BI exposure of 110,400 if the system is completely out of action. A major inverter fire (rare but possible) could cause a 3-6 month system outage while insurance claims are settled and new equipment is sourced. BI extension covering this exposure typically costs 1,500-4,000/year in additional premium — a sound investment given the scale of potential loss.
How solar panels affect building sum insured
Installing solar PV increases the replacement value of the building — specifically the M&E engineering element of the building sum insured. This has two important implications.
Underinsurance risk. The building’s declared sum insured must include the full replacement cost of the PV installation. For a 300 kWp system at 840/kWp installed cost (252,000), the sum insured should increase by approximately 252,000. Failure to increase the sum insured creates underinsurance. UK building insurance policies typically contain average clauses (proportional claims settlement) that reduce claims in proportion to the degree of underinsurance. Underinsurance of 20% on a 500,000 claim results in the insurer paying only 400,000.
Notify insurer at installation, not after. The timing of notification is critical. Most property insurance policies require notification of material changes to the insured property before the change takes effect. Installing 252,000 of electrical equipment on the roof without notifying the insurer before installation could void cover for the PV asset — and potentially for roof damage incidents where the PV equipment is argued to be a contributing factor.
The standard process: inform the insurer at design stage (before works commence), obtain written confirmation of policy extension, confirm any premium adjustment, and receive updated policy schedule including the PV asset in the sum insured.
Underwriting questions: what insurers want to know
Commercial property insurers will ask some or all of the following questions when a solar PV installation is notified. Having answers ready speeds the endorsement process.
1. System capacity and description. kWp installed, panel manufacturer and model, inverter manufacturer and model, system type (grid-connected, battery storage included or not).
2. Roof penetration method. Ballasted (no penetration) vs penetration-based mounting. Ballasted is lower risk from insurer perspective (no penetration of waterproof membrane); penetration-based requires confirmation of waterproofing method.
3. MCS certification. Was the system installed by an MCS-certified contractor? MCS is the quality standard that insurers use as a proxy for installation quality. Non-MCS installations typically attract significantly higher premiums or refusal to cover.
4. Structural certification. Was the roof structural assessment conducted by a structural engineer? Copy of structural engineer’s confirmation letter typically requested.
5. Fire risk. Is there battery storage? If yes: battery chemistry (LFP vs NMC), storage location (indoor/outdoor), fire suppression system fitted (type and coverage), BMS monitoring capability.
6. EICR / commissioning documentation. Has the system been commissioned to IEC 62446 and certified under BS 7671? Insurers increasingly request commissioning certificates for large commercial systems.
7. O&M contract. Is there a maintenance contract in place? Annual inspection and EICR? Some insurers offer premium discounts (5-10%) for documented O&M arrangements.
What voids cover on PV installations
Four scenarios that can void or limit insurance cover on a solar installation:
1. Late notification of installation. As described above — notifying after installation rather than before can result in the period between installation and notification being uninsured.
2. Non-MCS installation. Some insurers will not cover PV systems installed by non-MCS certified contractors or will charge significantly higher premiums. If a building has an existing non-MCS PV system from an early FIT-era install, verify the insurer’s position explicitly.
3. Battery storage added without notification. Battery storage materially changes the fire risk profile. Adding battery storage to an existing PV policy without notifying the insurer voids cover for fire events attributable to or occurring proximate to the battery.
4. Maintenance failure. Some policies include a maintenance condition — requiring the system to be maintained to manufacturer standards. Documented failure to maintain (no EICR in 5 years, known faults unaddressed) can give insurers grounds to dispute liability on related claims.
MCS certificate requirement for insurers
The MCS (Microgeneration Certification Scheme) installation certificate is increasingly required by commercial property insurers as a condition of covering the PV asset. The certificate confirms:
- System was designed and installed to MCS standards (MCS 001/002 for solar PV)
- Installer holds current MCS certification for commercial PV work
- System specification (panel model/capacity, inverter model, system capacity)
- Site address and installation date
The certificate is issued by the installer on MCS Connect (the MCS online database) and is accessible to third parties via the database search. For due diligence and insurance purposes, the unique MCS certificate reference number allows verification without physical document exchange.
For very large systems (above 5 MWp), MCS certification is not available (the scheme covers up to 5 MWp) — large systems are covered under NERS (National Electricity Registration Scheme) or directly under BS 7671 and G99 Engineering Recommendations.
Specialist brokers: who handles commercial solar
General commercial property insurance brokers can handle straightforward solar endorsements on existing policies. For complex situations (large systems, battery storage, PPA structures, portfolio clients), specialist brokers provide better technical capability and market access.
Specialist brokers active in commercial solar insurance (2026):
Towergate Energy. Part of Ardonagh Group. Dedicated renewable energy unit covering commercial solar, battery storage, and wind. Strong market relationships with Allianz, AXA, and Zurich for large commercial systems.
Marsh Commercial Renewable Energy. Global broker with dedicated UK renewable energy practice. Handles complex portfolio-level cover for REIT landlords and large corporate PV portfolios.
Lockton Renewable Energy. Dedicated renewables practice, handles large commercial solar and co-located battery storage.
Gallagher Renewable Energy. Strong track record in commercial rooftop solar, including multi-let office buildings and PPA-structured systems.
Willis Towers Watson (WTW) Power and Renewables. Typically handles systems above 1 MWp; broker of record for several major UK REIT solar portfolio programmes.
For standard commercial office systems under 500 kWp without battery storage, an existing commercial property broker with a brief explaining the solar parameters is typically sufficient. For systems above 500 kWp, battery storage-equipped systems, or PPA-structured installations, a specialist broker is worth the time investment.
Key takeaways
- All-risks cover protects physical assets; BI extension is needed to cover loss of electricity savings during outage — request both explicitly
- Notify the building insurer before installation commences, not after; late notification can void cover for the period between install and notification
- MCS certification is increasingly required by commercial insurers as a condition of cover — non-MCS installs attract higher premiums or may be refused
- Battery storage must be explicitly notified and the fire suppression and BMS specifications shared with the insurer
- Sum insured must increase to reflect PV replacement cost; failure to update creates underinsurance that reduces claims settlement proportionally
- Specialist brokers (Towergate Energy, Marsh Commercial, Gallagher) provide better market access for complex or large commercial solar insurance