Case study · Warehouse · Bedford
250kW. 4.2-year payback. 18 months in.
A Bedford distribution centre with a flat roof and a 200,000 kWh annual draw. We modelled three array sizes and recommended the smallest that paid back inside five years — here’s why.
250kW
System Size
65%
Energy Offset
£42k
Annual Savings
4.2yrs
Payback Period
The Challenge
A major logistics company operating a 40,000 sq ft distribution warehouse in Bedford approached us with significant energy cost concerns. Their warehouse operations ran 18 hours a day, 6 days a week, with substantial electricity consumption for:
- High-bay LED lighting throughout the facility
- Refrigeration units for temperature-sensitive goods
- Conveyor systems and material handling equipment
- Office areas and staff facilities
- Growing fleet of electric forklift chargers
Annual electricity costs exceeded £65,000 and were rising with energy price increases. The company also had corporate sustainability targets requiring a reduction in Scope 2 emissions.
Our Solution
After conducting a detailed site survey and energy analysis, we designed a 250kW rooftop solar PV system optimised for the warehouse's consumption profile:
System Design
- 540 solar panels - High-efficiency 460W monocrystalline panels
- East-West orientation - Maximised energy capture throughout the day, matching operational hours
- Ballasted mounting - No roof penetrations required on the flat membrane roof
- 3 string inverters - SolarEdge commercial inverters with panel-level optimisation
- Remote monitoring - Real-time performance tracking and alerts
Installation Approach
The installation was completed over 3 weeks with zero disruption to warehouse operations:
- Weekend crane lifts for panel delivery to roof
- Installation work during daylight hours while operations continued below
- Electrical work scheduled during shift changeovers
- Full commissioning and grid connection within planned timeline
Technical Specifications
System Details
- System capacity: 250kWp
- Panel type: JA Solar 460W mono
- Number of panels: 540
- Inverter: SolarEdge SE100K (x3)
- Mounting: K2 ballasted flat roof
- Roof area used: 1,800m²
Performance
- Annual generation: 225,000 kWh
- Self-consumption rate: 92%
- Grid export: 8%
- CO2 offset: 52 tonnes/year
- Performance ratio: 85%
- System efficiency: 21.3%
Results
The system has been operational for over 12 months and has exceeded performance expectations:
£42,000
First year savings
65%
Electricity cost reduction
52 tonnes
CO2 avoided annually
Financial Summary
- Total investment: £175,000
- Annual savings: £42,000 (year 1)
- Payback period: 4.2 years
- 25-year return: £850,000+ in savings
- System warranty: 25 years performance guarantee
Client Feedback
"The installation was completed on time and with no impact on our warehouse operations. The savings have exceeded our expectations, and we're now looking at adding battery storage to capture even more value from the system."
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