Factory Solar Panel Installation Process UK: Complete Step-by-Step Guide
Understanding the factory solar panel installation process helps manufacturers plan effectively and minimise disruption. This comprehensive guide walks through every stage from initial assessment to system commissioning.
Installation Timeline Overview
Pre-Installation (4-8 weeks)
- 1. Initial Energy Assessment
- 2. Site Survey & Structural Assessment
- 3. System Design & Engineering
- 4. DNO Application
Installation (2-6 weeks)
- 5. Planning & Permits
- 6. Physical Installation
- 7. Testing & Commissioning
- 8. Handover & Monitoring Setup
Total Project Duration: 8-14 weeks for typical factory installations (100kW-1MW)
Installing solar panels for factories is a significant investment that transforms your facility's energy profile for 25+ years. Unlike residential installations, factory solar requires careful coordination with production schedules, structural engineering, and grid infrastructure.
With over 650 UK factory installations completed, we've refined a proven 8-step process that ensures zero production disruption while delivering optimal system performance. Here's exactly what to expect at each stage.
Step 1: Initial Energy Assessment
Duration: 1-2 weeks
Every factory solar project begins with a comprehensive energy assessment. This critical first step determines system viability, optimal sizing, and projected returns.
What We Analyse
- 12-24 months of electricity bills: Understanding consumption patterns, peak demand periods, and seasonal variations
- Half-hourly consumption data: Matching solar generation profile to actual usage patterns
- Current electricity contract: Unit rates, standing charges, and contract end dates
- Future energy requirements: Planned expansion, new equipment, or EV charging infrastructure
- Operating schedules: Shift patterns, weekend operations, and seasonal production changes
This assessment generates your preliminary ROI projection and recommended system size. For detailed financial analysis, see our Industrial Solar Panel ROI Calculator.
Factory Owner Action Required
Provide access to electricity bills and consumption data. If available, half-hourly meter data significantly improves system optimisation accuracy.
Step 2: Site Survey and Structural Assessment
Duration: 1-2 weeks
A physical site survey confirms the technical feasibility identified in the energy assessment. This is where our engineers evaluate your roof's solar potential and structural capability.
Roof Assessment Components
Structural Evaluation
- Roof age and condition
- Material type (metal, membrane, composite)
- Load-bearing capacity assessment
- Purlin spacing and condition
- Existing roof penetrations
Solar Potential Analysis
- Roof orientation and pitch
- Shading from adjacent structures
- Available unobstructed area
- HVAC equipment locations
- Access requirements for maintenance
For older buildings or those with unusual roof structures, we commission a BS 6399-compliant structural engineer's report. This ensures your roof can safely support the additional 10-15 kg/sqm dead load plus wind loading. Learn more in our guide to factory roof weight load requirements.
Electrical Infrastructure Survey
Our electrical engineers assess your existing infrastructure to determine the optimal connection point:
- Main switchboard capacity: Available space for solar inverter connection
- Incoming supply capacity: Maximum export capability without upgrade
- Cable routes: DC and AC cable pathways from roof to switchboard
- Meter configuration: Current metering setup and upgrade requirements
Step 3: System Design and Engineering
Duration: 1-2 weeks
Using data from the energy assessment and site survey, our engineering team creates a custom system design optimised for your factory's specific requirements.
Design Deliverables
- Panel layout drawings: Precise placement of every panel, maximising usable roof space
- Electrical single-line diagram: Complete system architecture from panels to grid connection
- String configuration: Optimal panel groupings for maximum efficiency
- Inverter specification: Equipment sizing matched to generation and export requirements
- Mounting system specification: Appropriate fixing method for your roof type
- Generation projections: Monthly and annual kWh forecasts with P50/P90 confidence levels
We present the complete design package including final costings, ROI analysis, and financing options. For detailed cost breakdowns, see our Factory Solar Panel Costs UK 2025 guide.
Step 4: DNO Application and Grid Connection
Duration: 4-12 weeks (runs parallel to other activities)
All grid-connected solar systems require approval from your local Distribution Network Operator (DNO). This ensures the local electricity network can safely accept power exported from your system.
Application Types
| Application Type | System Size | Typical Timeline | Complexity |
|---|---|---|---|
| G98 Notification | Up to 16A/phase (3.68kW single-phase) | Immediate | Low |
| G99 Stage 1 | Up to 50kW | 4-6 weeks | Medium |
| G99 Stage 2 | 50kW - 1MW | 8-12 weeks | High |
| G99 Stage 3 | Above 1MW | 12-20 weeks | Very High |
We handle the complete DNO application process, including technical submissions and liaison with network engineers. In areas with constrained networks, we may recommend export limitation or battery storage to accelerate approval.
Step 5: Planning and Permits
Duration: 0-8 weeks (depending on requirements)
Most factory rooftop solar installations qualify as Permitted Development, meaning no formal planning application is required. However, certain situations require planning approval.
Permitted Development (No Planning Needed)
- Panels do not protrude more than 200mm from roof surface
- Installation does not project above highest part of roof
- Building is not in a conservation area
- Building is not listed
- Not visible from a highway in Areas of Outstanding Natural Beauty
Planning Permission Required
- Listed buildings or structures
- Conservation areas (may require)
- Ground-mounted systems over certain thresholds
- Systems that significantly alter building appearance
- Some World Heritage Sites
We conduct a planning assessment as part of the site survey and advise on any requirements. Where planning is needed, we prepare and submit applications on your behalf.
Step 6: Physical Installation
Duration: 1-4 weeks (depending on system size)
The installation phase is carefully coordinated to minimise disruption to your operations. Our project managers work with your facilities team to schedule work around production requirements.
Installation Sequence
Scaffolding and Access Equipment
Safe roof access established. For large flat roofs, we use mobile elevated work platforms (MEWPs) to avoid scaffold costs.
Mounting System Installation
Rail systems or ballasted frames installed. On metal roofs, we use non-penetrative clamps where possible. Flat roofs typically use weighted frames requiring no roof penetrations. The mounting approach is determined by the structural assessment completed in Step 2 - see our roof load capacity guide for details on weight considerations.
DC Cable Installation
Cables routed from panel locations to inverter positions. Conduit or cable tray installed for protection and tidiness.
Panel Installation
Solar panels mounted and electrically connected. A team of 4-6 installers can mount 100+ panels per day on suitable roofs.
Inverter and Switchgear Installation
Inverters mounted (typically internally), AC isolation, generation meter, and connection to main switchboard.
Grid Connection
Final connection to your electrical system. Brief power outage (typically 2-4 hours) required for safe connection.
Zero Production Disruption Guarantee
We schedule all noisy or disruptive work outside production hours. The only essential downtime is the brief power outage for final grid connection, which we schedule for weekends or shift changeovers.
For 24/7 operations, we can arrange temporary power or phased connections to maintain continuous production.
Step 7: Testing and Commissioning
Duration: 1-3 days
Before your system goes live, comprehensive testing ensures safety, compliance, and optimal performance.
Commissioning Tests
| Test | Purpose | Standard |
|---|---|---|
| Insulation Resistance | Verify cable and connection integrity | BS 7671 |
| Earth Continuity | Confirm protective earthing throughout | BS 7671 |
| String Open Circuit Voltage | Verify panel connections and polarity | IEC 62446 |
| String Short Circuit Current | Check panel performance | IEC 62446 |
| G99 Protection Settings | Verify anti-islanding and grid protection | ENA EREC G99 |
| Functional Performance | Confirm system generates and exports correctly | MCS MIS 3002 |
All tests are documented in a comprehensive commissioning report, forming part of your installation documentation and warranty package.
Step 8: Handover and Monitoring Setup
Duration: 1 day
The final step ensures you have everything needed to operate, monitor, and maintain your system for the next 25+ years.
Handover Package Contents
- MCS Certificate: Required for SEG registration and grant claims
- Electrical Installation Certificate: BS 7671 compliance documentation
- As-Built Drawings: Final system layout and wiring diagrams
- O&M Manual: Operation guidance and maintenance schedules
- Product Warranties: Panel (25-year), inverter (10-year), and workmanship (10-year) guarantees
- DNO Approval: G99 commissioning confirmation
- Structural Sign-Off: Engineer's confirmation of installation compliance
Monitoring System Activation
Your monitoring platform is configured to provide real-time visibility of system performance:
- Real-time generation data: Current output and daily/monthly totals
- Self-consumption tracking: How much solar you're using vs exporting
- Financial savings: Automatic calculation of cost savings
- Performance alerts: Instant notification of any system issues
- Environmental impact: CO2 savings and equivalent metrics
For ongoing system care, see our guide to factory solar panel maintenance.
Factory Solar Installation FAQs
How long does the entire process take?
Typical projects complete in 8-14 weeks from initial assessment to commissioning. The main variable is DNO approval time, which depends on system size and local network capacity.
Will installation disrupt our production?
No. We schedule all installation work to avoid production interference. The only essential downtime is 2-4 hours for grid connection, which we arrange for weekends or shift changes.
What if our roof needs repairs?
We assess roof condition during the site survey. If repairs are needed, we can either coordinate with roofing contractors or recommend addressing issues before installation. Solar panels actually extend roof life by protecting from UV and weather.
Do we need to do anything during installation?
Minimal involvement required. We need site access, a designated contact for coordination, and brief power shutdown approval for grid connection. All technical and regulatory matters are handled by our team.
Ready to Start Your Factory Solar Installation?
Get a free comprehensive assessment including energy analysis, site evaluation, system design, and detailed ROI projection.
Request Free AssessmentRelated Resources
Complete Guide to Factory Solar Panels UK 2025
Comprehensive resource covering all aspects of industrial solar
Factory Solar Panel Costs UK 2025
Detailed cost breakdown by system size and installation type
Factory Roof Weight Load Requirements
Structural considerations for roof-mounted solar systems
Industrial Solar Panel Grants UK 2025
Available funding and tax incentives for factory solar