In January 2016, EvoEnergy completed the installation of the UK’s 4th largest rooftop solar PV system in the UK – the 2nd largest on a single building – for Lyreco, the Global office and workplace solutions provider, at their National Distribution Centre in Telford.
The 3.811 MWp array, made up of 13,860 Trina 275W panels, was fitted on to the roof of Lyreco’s 15-acre logistics site between October 2015 and January 2016 to primarily cut its carbon footprint and is one of only five rooftop systems in the UK to exceed a yearly output of 3.2 GWh.
It was the largest rooftop PV system to be installed in the UK in 2015 and also the first in the country to use large central inverters (2 x ABB 1.56 MW) more commonly used for solar farms, bringing ground mount centralised inverter technology to a rooftop installation for the first time.
Owned and operated through a 20-year power purchase agreement by Addison Energy Limited – a company funded by Guinness Asset Management’s EIS service – the system will save Lyreco more than £53,000 a year on their energy bills, as well as cutting annual carbon emissions by 1,700 tonnes – making the whole site carbon neutral in terms of electricity usage.
Nick Dacey, Logistics Director for Lyreco, commented:
“We have a large warehouse here in Telford with a large open space on the roof and it recently became obvious that solar panel technology had reached a point where it would be economic for us to engage in that.”
Dr Malcolm King, Investment Manager for Guinness Asset Management, added:
“We are delighted to have worked with Lyreco and EvoEnergy to complete one of the UK’s largest rooftop solar installations. This demonstrates our ongoing ability to source and deliver high quality projects for our investors.”.”
EvoEnergy were initially invited to tender for the work and were awarded the contract thanks to their innovative technical solutions and willingness to also take on responsibility for restoring the roof to the best condition possible prior to the installation of PV. In addition, EvoEnergy also agreed to take full contractual responsibility of maintaining the rooftop as well as the solar PV system for an initial 5 years until 2021.
With the roof repairs agreed, before any PV installation could take place, EvoEnergy replaced 50,000 of the original roof fixings, as well as repairing and treating over 10,000 linear metres of cut-edge corrosion; each area of corrosion also required four separate treatments meaning the total treatment was closer to 40,000 linear metres.
Lead by an experienced Project Manager, a team of 30 installers and electricians worked on-site during the installation process, even working through the wettest December ever recorded in the UK. The panels were fitted in just three months onto a rooftop the size of 7.5 football pitches, requiring installers to often walk the equivalent of 14 miles per day manually carrying panels one at a time – each weighing around 40 lbs – from the edge of the building to the centre of the roof space; pallets of panels were lifted in turn by high-bay machinery and then manually unloaded.
Expert high-voltage electrical solutions were required from EvoEnergy for the PV system to integrate with the existing 11,000v on-site power supply, which the team handled by incorporating specially-built step-down voltage regulators into the system’s design. This solution allowed Lyreco to install a PV system much larger than initially planned.
In total, over 100 miles of cabling was used for the installation, equivalent to running a single cable from Birmingham to London.
Health and safety
Minimising the disruption to Lyreco’s day-to-day operations was of paramount importance, as was the health and safety on-site of the installers, staff and visitors. EvoEnergy therefore employed a single point of access to the rooftop via a custom-built temporary staircase. Workers on the roof then utilised innovative rope-access techniques to safely move around the roof space with wind-resistant demarcation systems also fixed around the roof perimeter to prevent workers venturing too close to the edge. Together, these measures eliminated the need for any scaffolding to be required onsite whilst ensuring that the highest health and safety standards were maintained.
James Sutton, Project Manager on-site for EvoEnergy, said:
“As it’s a funded project, we needed to deliver a turnkey installation fit for purpose for years to come. We carried out the work in seven phases, with rope-access teams working ahead of our installers to make each workspace safe beforehand.
“With similar large-scale projects to our name already, we were equipped to keep work moving on-site at a steady, continuous pace. Our technical team, meanwhile, had the forward thought to propose the use of two large ABB 1.56MW central inverters, often used in ground mount installations, mounted adjacent to the building, saving Lyreco the space of more than 100 regular string inverters.”
“It takes a huge amount of careful planning and execution to make a job this large run without any hitches. It’s been a team effort to get here; one that’s required all of our electrical, mechanical and civil engineering expertise.”
Throughout the installation, 267 sky lights were also required to be covered to prevent any serious accidents. Another new, innovative health and safety practise was therefore employed to neutralise the risk through temporary sky light covers that acted as an additional precaution (to rope-access) using custom-sized netting structures that would act as a safety net in the worst case scenario.
Ground-mount inverters and sub-station
Meanwhile, on the ground, EvoEnergy were also busy preparing a base for the two large ABB 1.56MW central inverters, each weighing 4.6 tonnes. The inverters would receive DC electricity generated by the solar panels via 40 string boxes on the rooftop. The cabling – stacked in a ‘triangle’ formation for optimum heat dissipation – would neatly roll off the rooftop to ground level before connecting to the inverters.
A large sub-station, weighing over 7 tonnes, would also sit in-between the two inverters. The large sub-station was necessary to receive the output from the inverters (690v) and step this up to 11,000v for distribution into Lyreco’s existing high-voltage power supply.
For this equipment to be installed, the ground first had to be excavated so new foundations could be put in place to house both the inverters and sub-station, in addition to a purpose built steel frame, stairwell, and security fence. A steel barrier, similar to what is used on motorways, was also positioned in front of the fencing as an extra precautionary measure due to the high volume of HGV lorries driving past every day.
Following the installation, EvoEnergy implemented various platforms for remotely monitoring the system which gave both top-level generation data and detailed performance statistics (of each string connected to the inverters) in real-time. In the event of low generation, the platform would also inform EvoEnergy via SMS and email, prompting immediate investigation.
To enable accurate performance ratio calculations, EvoEnergy also installed an ABB weather station, which incorporates wind speed, ambient temperature, PV panel temperature and irradiance. The weather station is linked up to the system using data-loggers and allows the monitoring system to accurately calculate the performance of the PV system.
Award winning installation
In December 2016, the installation was awarded ‘commercial rooftop installation of the year‘ at the Smart Solar UK Awards with the array also being influential to helping Lyreco win multiple environmental awards throughout the year.