Summer of free power for dairy farm

A dairy farm in Cornwall has enjoyed a summer of free electricity to power its milking machine and water heating thanks to a solar PV array fitted to the roof of its cow shed by Photon Energy.

Photon Energy, one of the UK’s leading independent installers of micro-generation technologies, was tasked in December 2011 to fit a 50kW system to the building at Trengwainton dairy farm in Penzance.

The array was estimated to bring in about £21,200 annually through savings and Feed-In Tariff payments. Over a year it is projected to generate around 39,000 kWh of electricity and save over 21 tonnes of CO2 emissions.

Photon Energy was responsible for the design, project management, installation and
commissioning of the system. It put its top team on the job to ensure the farm got its solar PV array in time to qualify for the higher FIT.

As the clock ticked down towards the date after which the fixed 25-year payments would be lower, the experienced team had to overcome a series of obstacles.

These included the unusual requirement of sourcing PV panels that were ammonia-resistant because of the atmosphere from the barn where the cows were housed below.

The strength of the roof, made up of fibre cement sheets, also had to be carefully assessed to make sure it could carry the extra weight. As a precaution, the installation team worked on boards with a safety net below.

“We are very pleased with our PV installation,” declared Trengwainton Farm owner Stephen Bone.

“During the summer months, the output from the PV system covers our
electricity needs for milking, and we are still a net exporter of

“Whilst the initial cost was higher than for a wind turbine, the PV system is maintenance-free and has very low running costs.”

Rolf Oldach, a director of Photon Energy, added: “It was a challenge to complete the
installation within the time available. Thanks to the co-operation of everyone
involved the work was completed in time.”

The PV modules were installed on the main barn’s roof which faces south-east with a pitch of 15 degrees. They were clamped using an aluminium rail mounting system. The AC cable run was long as the distribution board was in a different building.

The ventilation gaps between the sheets were used to fix the hanger bolts to the purlins below. Scaffolding for safe access to the roof was provided by a local contractor.