Mossy Hill Substation

Exhibition Sessions

In May 2024, exhibition sessions were held for the Mossy Hill substation. All information from the local exhibitions has been reproduced here to allow easy access. 

Mossy Hill Substation

Site Location 

The substation site is located at the northern end of the consented wind farm, south of, and close to, the main A970 road running through the wind farm site. Access will be via the junctions already consented for the wind farm. 

A large area has been defined in the Proposal for Application Notice (PAN) submitted to Shetland Island Council. This allows plenty of flexibility for the final layout and exact location to be defined following further studies and feedback from stakeholder engagement. 

About the Proposal

The new substation is required to connect the consented Mossy Hill Wind Farm into new electricity grid infrastructure that Scottish and South Energy Network Transmission (SSENT) are installing through the site, from Kergord to Gremista. This infrastructure comprises two 132kV underground cables, with the connection for Mossy Hill connecting into one of these cables. The wind farm operates at 33kV and the new substation operates at 132kV. The substation will transform the voltage from 33kV to 132kV. 

The Kergord to Gremista cables form a key part of the new electricity network in Shetland and will allow customers to be supplied directly from the Scottish Mainland via the new subsea cable. The new substation will therefore include switchgear and associated protection equipment to ensure both supplies to customers and the wind farm operate reliably.

Statkraft has a grid connection agreement with National Grid ESO which is the licenced energy system operator for Great Britain. Under this agreement it is required to consent the new substation.

Proposed Development

This substation development is to replace two smaller substation buildings that were consented as part of the Mossy Hill Wind Farm approval.

The majority of the new substation will be built, owned and maintained by SSENT and operated by National Grid ESO. It is expected that the substation will comprise of two main buildings: the larger one for SSENT and the smaller one for Statkraft. The SSENT building will contain most of the electrical; switchgear to allow Mossy Hill to connect into one of the Kergord to Gremista cables. The Statkraft building will contain a transformer to step up the voltage from 33kV to 132kV.

There will also be two smaller buildings, a control and welfare building for SSENT and a building for Statkraft which will bring together the cables from the wind turbines. The latter will also include Statkraft’s local control room and welfare facilities for staff working on the wind  farm.

During construction, each of the two main buildings will have its own dedicated construction compound that will be removed upon completion of the substation.