Case Study - Rooftop Solar

Supermarket Rooftop Solar

Across England

Green Cat Renewables (GCR) provided Pre-construction Technical Due Diligence for a portfolio of three rooftop solar installations totalling 2.6MWp on the roofs of large supermarkets. The rooftop arrays supply the host supermarkets energy, contributing to a reduction in import of energy from the grid.

Pre-construction Due Diligence focused on a review of the site configuration, planning requirements, electrical design, structural appraisal and roof condition, CDM and H&S, and grid connection. Additionally, assumptions made within the contractors Energy Yield Assessment were reviewed and an analysis of the user’s energy consumption undertaken to quantify the contribution the rooftop array would make to the building’s energy import.

The consumption analysis indicated that over 97% of energy generated by the solar arrays would be consumed by the supermarkets, reducing the import requirements by 18% across the sites.

Cable runs, electrical configuration, location of inverters, shut-down procedures, access, roof conditions, and roof penetrations were all considered when assessing the suitability of the design. As the sites are located in a built-up area with roofs at a low inclination angle, soiling on the panels was a consideration and recommendations were made for cleaning of modules and loss assumptions within the Energy Yield Assessments. 

Grid constraints at each site required the incorporation of G100 limitation devices with GCR conducting an assessment of potential curtailed export.

The post-construction review looked at the project completion documentation for suitability for the ongoing operation of the sites. Provision of sign-off documentation and DNO approval was essential to allow continued export of energy to the grid, and relevant Health & Safety documentation was reviewed to ensure compliance with relevant Health and Safety guidance.

A review was then conducted of the Contractors Performance Ratio (PR) calculation to verify methodology and adherence to the EPC Contract.

Key Data
  • Combined 2.6MWp solar across 4 rooftops
  • The portfolio is comprised of a 894kWp, 746kWp, and 589kWp, 370kWp array across 4 rooftops
  • Utilises existing supermarket roof structures eliminating any additional land requirement
  • 5,562 solar modules to be installed
  • Over 97% of solar energy produced by the arrays used by the host supermarkets
  • 18% reduction in energy import used by the host supermarkets