EvoEnergy was commissioned by the University of Cambridge to design and install a 4.64kWp system consisting of 16 bespoke 290Wp mono-crystalline panels, installed on four custom fabricated solar ‘tree’ frames. The system has a predicted yearly output of 3,868 kWh/year, saving 2,197kgCO2/year. The project was the result of an open tender which EvoEnergy won due to their innovative and creative system design.
The brief for the project was to design a system that was innovative, attractive and vandalism resistant. The system was sized to offset 10% of the University Library’s CO2 emissions (1767.1 kgCO2p.a.). EvoEnergy proposed three options, including the solar trees, although only three trees were originally proposed at 1.33kWp each, to meet the brief.
The solar trees were installed adjacent to the University library in the car park. As with any ground mounted system planning permission was required, therefore the trees were set away from the public roads to minimise
Concrete foundations were laid down prior to the installation of the solar trees, into which the frames were fixed. The panels were then lifted by cranes onto the trees and fixed to mountings. Although previous ‘Solar Tree’ designs had been successfully installed, tests were undertaken by EvoEnergy to ensure sufficient strength of both the welds and fixing points that hold the frame together.
The four trees each comprise of four 290Wp panels, giving a kWp of 1.16 per tree. By custom fabricating the trees, it was possible to use the optimum orientation and angle for the panels, which is a south facing fixing at 30 degrees. Each tree has its own SMA Sunny Boy inverter, meaning the system runs in parallel loops, and has a Sunny Webbox, which measures the output hourly.
The system was up and running on the 22nd March, and in the first 12 weeks of operation, it has generated 1622kWh of electricity. This amounts to a feed-in tariff payment of £694, on top of a reduction in electricity costs.
