West Bletchley Rail Depot Solar PV Installation

Overview

• Location: Bletchley Railway Depot

• Date of Installation: February 2025

• Type: Commercial

• Mounting Type: Ground-mounted, 30-degree orientation

• Panel Count: 340 × Trina Vertex S TSM-450W NEG9R.28

• System Size: 153 kWp

System Overview

The installation comprises 340 × Trina Vertex S 450W solar panels, paired with two Solis 60kW 5G three-phase inverters. The panels are mounted on a Fastenol ballasted ground-mounted tray system, with each panel requiring 36 kg of ballast. The project includes full electrical work, commissioning, certification, and notifications.

Performance Estimates

Annual Energy Generation, Consumption & Grid Export

• System Capacity: 153.00 kWp

• Array Orientation: 30°

• Panel Inclination: 10°

• Estimated Annual System Output: 128,920 kWh

The solar PV system is expected to generate approximately 128,920 kWh of electrical energy per year.

Due to the high anticipated on-site electrical demand, only a small amount of energy is expected to be exported back to the grid. Nevertheless, the solar PV system will be eligible for the Smart Export Guarantee (SEG), allowing any excess electricity exported to the grid to be sold back to an electricity supplier. More information on SEG eligibility and applications can be found on Ofgem's website.

Environmental Impact

The system contributes significantly to reducing the property's carbon footprint:

• Annual CO₂ savings: 26 tonnes

• Equivalent to:

  • 67,000 miles driven by a diesel car (400g CO₂ per mile)

  • CO₂ absorption of approximately 1,322 – 3,061 mature trees annually (22kg CO₂ per tree per year)

Disclaimer: These calculations are based on estimated system output and standard carbon emission factors from the UK Government’s Greenhouse Gas Reporting: Conversion Factors 2024. Actual results may vary due to energy usage, weather conditions, and grid carbon intensity.

Performance and Financial Projections

Investment & Expected Savings

The total cost of the installed system was £88,950.00 (ex. VAT). Based on the system’s annual generation of 128,920 kWh and the current electricity price of 28p per kWh, the estimated first-year savings are approximately £36,000.

The estimated payback period for the system is 3 years, with the system continuing to deliver substantial energy savings over its 30-year lifespan.

Disclaimer: Payback periods are estimated based on current electricity prices and SEG rates. Future price changes, electricity consumption habits, and system performance may affect the actual payback timeline.

Live Monitoring and Updates

The installed system is monitored by Chiltern Solar via the SolisCloud App, which provides:

• Graphical display of power flow

• String-by-string monitoring

• System alarms and notifications

Frequently Asked Questions

How does shading affect this system?

• The system has an overshading factor of 0.95, meaning minor shading may slightly reduce efficiency but is not a significant concern.

What is the expected performance over its lifetime?

• Estimated 887 kWh/kWp of solar radiation per year, with an annual output of 128,920 kWh.

• While degradation over time is not explicitly stated, industry-standard degradation rates apply.

Installation

The system was designed and installed by Chiltern Solar Ltd, an MCS-accredited (NAP 28870) company and a Renewable Energy Assurance Scheme (RECC) member (No. 44711). The project included:

• Full mechanical and electrical installation

• Inverter programming

• System commissioning

Warranties and Guarantees

• JA Solar Modules: 25-year product warranty, 30-year performance warranty

• Solis Inverter: 5-year manufacturer warranty

• Chiltern Solar Installation: 5-year workmanship warranty