Lark Energy Connects UK's First 'Plug And Play' Rooftop System

The UK's electricity system was originally conceived and built around large centralised power stations, mainly in the industrial heartlands of the country, sending power across the regions along high voltage networks terminating in large regional sub-stations. Industrial and domestic customers are then fed power from the sub-stations through lower voltage networks in the local area.  Renewable energy has provided a significant challenge to the conventional system by generating electricity in smaller, local power stations and requiring power to travel in the opposite direction through the transmission lines.

Lark Energy, as a major solar developer, is working closely with the distribution network operators (DNOs) to address these challenges and its project at G's provides an example of an innovative solution to local grid constraints, resulting in the UK's first 'Flexible Plug & Play' scheme through UK Power Networks (UKPN).

G's have been growing, packing and marketing fresh vegetables for over 60 years. They are an intensive energy user but take their commitment to the environment seriously.  They are committed to a 30% reduction in carbon emissions by 2020. In 2013, the Ramsey site won the prestigious Marks and Spencer Plan A environment award.

They have been implementing energy efficiency and renewable energy measures for some time and in 2013 they awarded Lark Energy a contract to install solar panels on their cold store. 

On the face of it this was a straight forward roof-top installation on a site with a large, incoming high voltage grid connection. However, due to local generation and grid constraints UKPN, the local electricity network operator, refused to provide a conventional connection fearing adverse impacts on the network. This was despite the fact that the cold store operates 365 days a year and all the energy generated by the solar system will be used within the cold store rather than exported to the grid.

Instead, UKPN proposed to replace the existing sub-stations to enable connection at a cost of nearly £70,000 which would have involved extensive trenching across the entire frontage of the site. This solution was not financially viable to G's and the proposed disruption was unacceptable.

Fortuitously, UKPN had just launched a government-funded pilot project designed to find new ways of connecting renewable energy in areas of constrained grid.  The "˜Flexible Plug and Play' pilot scheme seeks to overcome these constraints by allowing the DNO to remotely manage exported energy to the grid. It aims to enable cheaper and faster integration of distributed generation, such as solar, into the electricity distribution network.

Lark Energy suggested that G's installation would be a good candidate for the pilot. However, as the first project of its type in the UK, Lark Energy had to navigate extensive design and contract requirements to even have the project accepted. Once accepted, Lark Energy then had to come up with the appropriate technical solutions required by UKPN, including limiting the size to 250kWp, and designing and installing specialist active network monitoring and power management systems. 

Once the solar system was installed, it took many weeks for the monitoring and management system to be perfected so that all data could be accessed remotely in real time and connection could be controlled by UKPN. It is now, however, fully functioning and providing significant clean power to G's cold store.

The project will feed into research that will be shared with all DNOs in the UK who face the challenge of connecting high levels of renewable generation over the coming years. It will enable them to explore cheaper "˜interruptible' connections using new control and monitoring smart technologies to improve the utilisation of existing networks instead of incurring expensive reinforcements.

Jonathan Selwyn, Lark Energy's Managing Director, stated that 'we were delighted to work with such a forward thinking company as G's on this innovative project. They needed to be extremely patient and understanding whilst we worked with UKPN to come up with the appropriate solution that suited all parties. We hope it can be the first of many such trial projects that eventually opens up the electricity network to a much greater volume of renewable energy generation.'