Council’s rural education centre beats power export limit

19  Hagg Farm 2Nottinghamshire County Council has become one of the first organisations in the UK to use an export power limiting system on a solar PV system.

Hagg Farm, an outdoor education centre for Nottinghamshire young people in the Peak District, was fitted with a 32 kWp system by EvoEnergy in September as part of the council’s wider efforts to reduce energy costs and cut its carbon footprint.

Because of the centre’s remote location, powered only by overhead lines, it is subjected to an export limit of 7 kWp set by the Distribution Network Operator (DNOs) on the amount of self-generated power it exports to the National Grid.

As a result, the array would have been limited to less than 25 per cent of its intended size were it not for the idea from EvoEnergy ( of fitting an Export Power Control (EPC) system at the site.

This solution, developed in partnership with Moody Automation, helps overcome one of the biggest barriers to the future integration of renewables systems into the existing power network.

The EPC system is comprised of conventional controls used worldwide in industrial automation. It can be implemented on virtually any size of solar array with inverters from a variety of leading manufacturers.

With the EPC now in place, the centre can now benefit from an estimated 25,000 kWh of self-generated energy per year, equivalent to a 13-tonne annual saving in CO2 emissions.

Tim Hickman, technical manager for EvoEnergy, said: “There was no ‘off the shelf’ solution to the export limit problem at Hagg Farm so our technical team had to develop something new to meet the needs of this project and others where we’re faced with similar limitations.

“The EPC ensures that the export power never exceeds 7kW for more than a few seconds – it’s an inventive answer to what is becoming a common requirement of the electricity network operators.

“As the Grid becomes increasingly congested with renewable systems, the issue of managing diversified power generation across the network isn’t going away’.

“We expect many more businesses and organisations to be faced with a limit on the size of their next array because of export limits, despite the fact that many will consume the majority of the power their solar system produces.

“An EPC, however, allows firms to still install large solar arrays by reassuring DNOs that the level of exported power is controlled and the electricity network will not be put at risk. This way the business can still benefit from the significant offset of imported energy costs during the daytime.”

The install was completed in less than two weeks and involved a team of five working on fragile slate roofs; some more than a century old. By using the SolarFlash™ system for slate roofs, the integrity of the roofs could be maintained to ensure compliance with the Microgeneration Certification Scheme.

Phil Keynes, energy team manager for Nottinghamshire County Council, said: “We were really pleased that EvoEnergy found a solution which enabled this installation to go ahead successfully. The centre was very keen to have PV as a showcase for renewable energy technologies.

“The PV at Hagg Farm are part of the Council’s £1.8million investment programme in solar panels, which is itself part of a wider programme of investment in renewable energy and energy efficiency across its estate.’’