This report examines the causes, origins, and key factors contributing to the reported increase in house fires involving Solar Photovoltaic (PV) systems across the UK.
📈 Incidence Rate and Location
Data indicates a rising trend in fire incidents involving solar PV systems, which correlates with the significant increase in UK installations. Recent figures suggest that fire services tackle an incident involving a solar panel almost every two days in the UK.
| Installation Type | Proportion of Incidents |
| Residential Buildings | Majority of incidents (e.g., 97 out of 151 incidents reported by one insurer in a two-year period). |
| Commercial Properties | Fewer incidents. |
| Solar Farms / Industrial | Fewer incidents. |
The overwhelming majority of reported fires occur in residential properties. This high incidence in homes suggests a potential correlation with installation and maintenance practices on smaller-scale, domestic projects.
🔥 Pinpointed Causes and Start Points
The root cause of fires linked to solar PV systems is almost always electrical failure, rather than an inherent flaw in the panels themselves. The start point of the fire is generally within the electrical components of the system.
Primary Causes (Root) and Start Points (Origin):
- Primary Cause: Poor Installation Practices or Installation Faults. This is consistently cited as the leading factor, contributing to a significant percentage of internal system faults that lead to fire.
- Primary Start Points:
- DC Isolators (Switches): Identified in historical studies as the component most likely to develop a fault leading to a fire.
- DC Connectors/Cabling: Electrical faults in these connections are a major cause.
- Inverters: Malfunctions or overheating in the inverter unit.
- The Solar Panels Themselves: Fires can originate on the panels due to electrical issues.
- DC Cabling and Battery Banks: Other vulnerable components cited as origins.
⚡ Key Factors to the Causes
The confirmed causes of electrical failure that ignite the fires are linked to multiple key factors:
- 1. Electrical Arcing (Arc Faults):
- This is the fundamental mechanism of fire ignition, occurring when high-voltage DC current “jumps” across a gap in a circuit.
- It is caused by loose connections, damaged wires, or faulty wiring/connectors resulting from poor installation. The high heat generated by the arc can ignite surrounding materials.
- 2. Component Defects and Low Quality:
- The use of poor quality or incompatible components increases the risk.
- Specific component failures, such as in junction boxes or DC isolators, are significant factors.
- 3. Ageing Systems and Lack of Maintenance:
- Older installations, particularly those installed during the initial rapid growth phase (e.g., Feed-in Tariff era), may be at a higher risk due to component degradation or initial poor installation standards that have not been rectified.
- Failure to perform regular inspection and maintenance allows minor electrical issues (like loose connections) to compound and escalate over time.
- 4. External/Environmental Factors:
- Moisture Infiltration/Water Ingress: Can lead to corrosion and electrical faults within connectors or other components.
- Hot Spots: Caused by the accumulation of dirt, debris, or foliage (like bird droppings) on the panels, leading to partial shading. The shaded cells act as resistors, generating heat that can eventually cause ignition.
- Extreme Weather: High winds can loosen connections or damage mounting systems, increasing the risk of arc faults.
⚠️ Mitigation Summary
The data strongly suggests that the risk of fire is significantly increased by substandard installation and a lack of preventative maintenance. The primary preventive measures revolve around ensuring installations are carried out by accredited, competent professionals and that systems are subject to periodic inspection and testing by qualified electricians.
Would you like me to find information on the specific regulations or best practices for solar panel installation and maintenance in the UK to help reduce these risks?
✅ RenewSolar Risk Mitigation and Remedial Action Plan: Solution Overview
The rise in PV-related fires is directly linked to electrical faults, most commonly due to poor installation and the degradation of components under UK weather conditions. The solution focuses on mitigating these risks through a structured inspection and maintenance regime.
🔍 Recommended Inspection and Maintenance Intervals (UK)
The frequency of professional PV system inspection is highly dependent on the system type and components. Below is a summary of recommended intervals from UK industry bodies and experts, focusing on residential systems:
| Service/Inspection Type | Recommended Frequency (General) | Key Industry Body Recommendation | Purpose (Risk Mitigation) |
| Visual/User Checks | Monthly/Quarterly | N/A (Owner responsibility) | Check for physical damage, new shading, debris/soiling, and monitor inverter status (lights/error codes). |
| Professional Electrical System Check (High-Voltage DC Systems) | Annually (High Risk) | MCS/Industry Experts | Critical check for high-voltage DC systems, focusing on electrical connections, cables, and isolators to prevent arcing. |
| Intermediate Maintenance & Full Electrical Condition Report (EICR) | Every 5 to 10 Years | IET/EICR Alignment | Comprehensive check aligning with fixed wire testing for the entire property. Checks AC components, grounding, and system integrity. |
| Full Maintenance Inspection (MCS) | Every 10 years (Intermediate) and 15 years (Full) | Microgeneration Certification Scheme (MCS) | Detailed system check by a certified contractor covering electrical safety and performance testing. |
| Professional Cleaning | Every 1-5 Years | Industry Experts (Varies by location) | Removes accumulated dirt, bird droppings, and debris that can cause “hot spots” and significant power reduction. |
Note: For high-risk or older high-voltage DC systems, an annual professional inspection is a critical measure to proactively identify and address hidden faults before they lead to an arc fault and fire.
✅ RenewSolar Risk Mitigation and Remedial Action Plan: Solution Overview
The rise in PV-related fires is directly linked to electrical faults, most commonly due to poor installation and the degradation of components under UK weather conditions. The solution focuses on mitigating these risks through a structured inspection and maintenance regime.
🔍 Recommended Inspection and Maintenance Intervals (UK)
The frequency of professional PV system inspection is highly dependent on the system type and components. Below is a summary of recommended intervals from UK industry bodies and experts, focusing on residential systems:
| Service/Inspection Type | Recommended Frequency (General) | Key Industry Body Recommendation | Purpose (Risk Mitigation) |
| Visual/User Checks | Monthly/Quarterly | N/A (Owner responsibility) | Check for physical damage, new shading, debris/soiling, and monitor inverter status (lights/error codes). |
| Professional Electrical System Check (High-Voltage DC Systems) | Annually (High Risk) | MCS/Industry Experts | Critical check for high-voltage DC systems, focusing on electrical connections, cables, and isolators to prevent arcing. |
| Intermediate Maintenance & Full Electrical Condition Report (EICR) | Every 5 to 10 Years | IET/EICR Alignment | Comprehensive check aligning with fixed wire testing for the entire property. Checks AC components, grounding, and system integrity. |
| Full Maintenance Inspection (MCS) | Every 10 years (Intermediate) and 15 years (Full) | Microgeneration Certification Scheme (MCS) | Detailed system check by a certified contractor covering electrical safety and performance testing. |
| Professional Cleaning | Every 1-5 Years | Industry Experts (Varies by location) | Removes accumulated dirt, bird droppings, and debris that can cause “hot spots” and significant power reduction. |
Note: For high-risk or older high-voltage DC systems, an annual professional inspection is a critical measure to proactively identify and address hidden faults before they lead to an arc fault and fire.
🛠️ RenewSolar Risk Assessment and Remedial Work (Solution)
The core solution for lowering insurance risk and ensuring system longevity lies in proactive, data-driven maintenance that addresses the known failure points in UK solar installations.
1. Proactive Fault Prevention: AFDD Upgrades
| Feature | Action | Risk Mitigation |
| Advanced Arc Fault Detection Device (AFDD) Installation | Installing AFDDs on DC lines (where applicable). | Direct Fire Prevention: AFDDs are designed to detect the unique electrical signature of an arc fault (the start of a fire) and shut the system down within milliseconds, preventing ignition. This is a critical safety upgrade, especially for older DC systems. |
2. Remedial Action: Replacing Known Defective Components
| Feature | Action | Cost & Impact |
| Replacement of High-Risk Components | Proactive replacement of known faulty or low-quality DC connectors and isolators that are prone to weather ingress and loose connections. | Low-Cost, High-Value: The cost of replacement parts is minimal (often under £40 for common items), yet this action eliminates the primary mechanical failure points that cause dangerous electrical arcing. |
3. Advanced Installation Check List & Data Recording
| Feature | RenewSolar Advantage | Risk Mitigation Value |
| Advanced Health Check and Testing | Going beyond standard compliance by recording additional data, such as connection resistance values (R-values) and using thermal imaging (Infra-red inspection). | Predictive Maintenance: Creates a baseline data record. Changes in resistance over time indicate developing loose connections or corrosion long before a system performance drop or fault occurs. Thermal imaging identifies invisible “hot spots” (early fire warning signs). |
| Weathering and Mechanical Stress Assessment | Thorough inspection for signs of weathering, chaffing cables, and loose mounting structures caused by UK wind/temperature cycles. | Physical Integrity: Addresses the risk of loose wiring that can wear through insulation and cause short circuits or arc faults in exposed environments. |
4. Lowering Insurance and Risk Profile
The perception that solar is “install and forget” is a primary driver of risk. By implementing the above measures, homeowners can gain a tangible benefit:
- Demonstrable Due Diligence: A detailed inspection and maintenance log, especially one confirming low resistance values and the installation of AFDDs, provides major insurers with quantifiable evidence of a lowered fire risk.
- Proof of Competency: Confirmed maintenance by accredited professionals ensures the system complies with the latest BS 7671 (IET Wiring Regulations) standards, which directly impacts a property’s insurability.
Cost Comparison: Prevention vs. Cure (UK Averages)
The data strongly supports your central argument: a small, proactive investment prevents a major, costly, and dangerous failure.
| Service Type | Typical Cost (UK Residential) | Primary Cost Component | Risk Mitigation Impact |
| I. Prevention (RenewSolar Service) | £185 – £250 | Labour for inspection, advanced testing (R-values, thermal imaging), and report generation. | Eliminates the risk of fire and major system failure. |
| Annual/Bi-Annual System Service | £100 – £200 | Visual inspection, cable/connection checks, basic testing. | Proactive identification of developing faults (e.g., loose wiring). |
| Proactive Component Replacement (Parts Only) | £30 – £50 (per installation) | Cost of new, higher-quality DC isolators or MC4 connectors. | Eliminates the known industry failure points (faulty connectors/isolators) at minimal material cost. |
| II. Reactive Cure (Fault Repair) | £1,000 – £4,000+ | Material and labour for replacement and call-out fees. | Cost of replacing key components that failed due to lack of maintenance. |
| String Inverter Replacement | £800 – £1,850 | New unit cost + specialist labour (needed roughly every 10-15 years). | Cost of replacing the system’s most expensive component, often due to voltage stress from panel faults. |
| Call-out for Major Electrical Fault | £150 – £350 (just to diagnose) | Specialist electrician call-out fee and initial labour for diagnosis. | Cost to investigate a sudden drop in output or system shutdown. |
| Fire Damage/Major Repair | £10,000+ (or total loss) | Full system replacement, roof repair, and potential structural damage (covered by insurance, but with excess, claim history, and massive disruption). | Worst-case scenario resulting from unaddressed DC arc faults. |
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