Greenfield Holdings was retained through Williams Southern, one of Sainsbury`s main contractors, to source and deliver a solar system which was to be installed onto the roof at the Darnley PFS which is part of The Darnley Supermarket in Glasgow.

The GHL team was made up of Active Technologies, who designed and manufactured the aluminum framing system for the arrays, TE Ramm, which handled the electrical design. TE Ramm’s engineers wired the whole system together and arranged the G59 submission to the DNO. Eddie Buckley handled the G83 Testing, RoofTech dealt with the installation of the frames and the Photovoltaic panels, Rain Racer provided to special self cleaning coating to each solar panel and Energy ICT provided the energy monitoring equipment. The energy meter was supplied by Elsevier while the solar panels were provided by Romag Holdings and the inverters were supplied by Fronius.

Active Technologies took the details of the kiosk roof and designed a framing system to best suit the sun tubes being fitted and to achieve an increased angle utilizing the angle of the roof, achieving a 17 degrees angle, south facing with reduced losses and increased efficiency whilst importantly maintaining the overall esthetics of the kiosk.

The frame consisted of extruded aluminum angle and box section mounted directly to the roof panel profile, meaning no framing fixings penetrated through the roof fabric.

Detailed calculations for wind lift/loading allowed Greenfield Holdings to reduce the overall weight of the system meaning no additional structural supports were required. The framing system was delivered in a kit form and was supplied with detailed fitting and mounting instructions ensuring an easy and swift installation.

TE Ramm installed the electrical element of this project in accordance with MCS guidelines, Construction (Design and Management) Regulations 2007 and Renewable Energy Assurance Limited (REAL) recommendations of which Greenfield is a member.

All of the operatives were UKPIA qualified to ensure the works are completed to meet current construction/petrol chemical regulations.

The installation consisted of three Fronius IG40 inverters, one on each phase, which converted the sun’s energy in to 3.24kW per phase, giving a total of 9.72kW. This is via 54 Romag SMT660-225 panels (18 panels per phase). Each panel can produce up to 225 watts under ideal conditions. Since the array was fully operational at peak times the power output has achieved 91% of the sites power requirements.

The Rain Racer On-Site-Service team coated the glass PV panels with their heavy duty polymer coating; improving the surface of the panels making them virtually self cleaning with anti static properties. To maximise the operating efficiencies of the panels, this specialist coating ensures more light is transmitted through the glass onto the cells for longer, even in bad weather.

As part of the monitoring process of the photovoltaic array, EnergyICT utilises the Elster A1700 meter (OfGem approved) to measure the kWh generated. This smart meter uploads the data to EnergyICT’s EIServer Webclient. This user-friendly, graphical display allows the operator to overlay different data streams, aiding the analysis of the information. Examples of the extra inputs can include half-hourly main electricity data and the regional weather data for the sites location. This first graph shows the total kWh generated by the PV array:

The following graph shows the kWh generated by the PV array (in red) overlaid with the sunshine hours for that site’s weather region. This is very useful as it can demonstrate that the PV array increases energy generation in line with amount of sunshine in that area. That may seem obvious, but it would highlight faults, inefficiencies or even the presence of detritus on the PV cells if an increase in sunshine was not reflected in increased energy generation. Happily, this is not the case with this example.


David Penfold from Sainsbury Supermarkets said, “We were very impressed with what Greenfield Holdings and their team of sub contractors achieved with Chingford, therefore we wanted to see if their work would be as effective on another site and agreed to carry out a second pilot scheme through one of our main contractors Williams Southern”.

“This installation has worked very well, and we are pleased with the quality of their work.”