Cranfield University

Ground Solar PV

A world-leader in aerospace and engineering education, Cranfield University contracted RenEnergy in 2019 to deploy a largescale ground solar array to help the institution operate more sustainably. This project is part of Cranfield’s ambitious target to halve its carbon footprint by 2020.

However, the motives for this project were not just environmental. Like many educational institutions, Cranfield’s electrical consumption was high, resulting in large expenditure on grid energy. The university already benefited from a combined heat and power (CHP) plant, so the addition of solar PV would allow Cranfield to recoup even more savings on its energy spend.

The installed ground array, which covers 5,858 M2, generates 1,000 MWh of electricity every year. This provides 5% of the site’s annual energy demand and is enough to power over 300 homes.

We negotiated several challenges to complete this installation. Most notably, the site is located next to the University’s airfield, which meant we had to liaise with the Civil Aviation Authority to ensure our design met with their stringent guidelines. We also had to contend with the potential presence of unexploded ordinance, since the site had been operational during the Second World War.

Additionally, the designs submitted as part of the tender specification were not best suited to the site. Fortunately, we were able to use our many years’ experience to overcome these challenges and reconfigure the design to maximise output and better complement the requirements of the site.

Integrating with the existing onsite CHP plant also posed a challenge, as the district network operator stipulated that the scheme must comply with the newly released G100 export limitation regulations. An export limit of 0kW was imposed on the site: no electricity generated from either the solar or the CHP can flow back to the national grid. To overcome this, we incorporated a system to monitor energy flow at the site’s main grid connection, then relay this information to both the CHP and the solar plant. So, if more energy is generated on-site than can be consumed (for example, on a sunny Sunday outside of the academic term) then the generation can be scaled down to comply with the G100 stipulation. Manually turning the generator off in these situations provides the same effect, but we wanted to avoid the unnecessary wear this would create on the system.

Like all our projects, the system we created for Cranfield is bespoke. We configured this ground array in a four-high landscape arrangement with row spacing limiting overall inter-row shading losses. To negotiate the presence of ordinance, a single pile frame provided the most flexibility for row placement. The array features 3,508 Hanwha Q-Cell QPLUS 285w PV Modules and 35 Fronius Eco/Symo String Inverters.

This was one of our most challenging installations, but we’re proud to say that Cranfield University is satisfied with the results. As well as providing the university with clean, cost-effective energy, it also creates an on-site renewable energy research facility for students. A further partnership between RenEnergy and Cranfield University is now in the pipeline.