Working with a distribution network operator (DNO): five lessons for your next energy efficiency project

From heat pumps and EV charging infrastructure to wider estate energy efficiency and decarbonisation programmes, many projects depend on access to electricity network capacity. 

Inadequate planning for this dependency can lead to unexpected costs, design changes and delays to delivery.

Through our DNO workgroup, we regularly bring together grant recipients and distribution network operators from across the country to share practical learning from real projects.

To help organisations navigate common challenges, we recently brought together Perth and Kinross Council and Scottish and Southern Electricity Networks (SSEN) to discuss their experiences managing network constraints, reviewing capacity requirements and delivering low-carbon projects.

The organisations worked together to deliver a project funded through Scotland’s Public Sector Heat Decarbonisation Fund, which is delivered by our teams at Salix on behalf of the Scottish Government.

Drawing on insights from both organisations, here are five key lessons that could help keep your next project on track.

1. Engage with your DNO as early as possible

Early engagement can help identify network constraints, upgrade requirements and potential costs before designs are finalised. 

Having this information early enables project teams to make informed decisions and avoid unnecessary redesign later in the process

SSEN highlighted the value of pre-application discussions, which can help organisations understand local network conditions and choose the most appropriate route through the connections process.

2. Plan for change 

Connection costs and timescales can change as projects develop. 

Network upgrades, equipment availability and third-party permissions can all affect delivery schedules.

Perth and Kinross Council shared its experience where network constraints affected heat pump projects at two rural schools, with upgrades taking more than a year following the initial application.

Building contingency into budgets and programmes can help manage this uncertainty. 

3. Combine desktop studies with site knowledge

Desktop assessments provide a useful starting point, but they do not always reflect site conditions. 

Perth and Kinross Council found that site visits helped to validate assumptions and identify practical constraints relating to access, land and existing infrastructure. 

Combining network information with local knowledge can help to uncover risks earlier and reduce the likelihood of costly changes later in the project.

4. Challenge your capacity assumptions

One of the most valuable lessons shared during the discussion related to electrical capacity planning.

Working with SSEN, Perth and Kinross Council reviewed demand assumptions across several sites and identified opportunities to significantly reduce capacity requirements while still meeting operational needs.

Examples included:

• New Perth High School: 1300 kVA reduced to 500 kVA
• Riverside Primary School: 400 kVA reduced to 199 kVA
• Auchtergaven Primary School: 218 kVA reduced to 110 kVA
• Bertha Park: 650 kVA reduced to 250 kVA 

The result, which is explained further in the webinar recording below, was reduced infrastructure requirements and estimated annual energy bill savings for the council of around £100,000.

5. Explore your options when constraints arise

Limited network capacity doesn’t automatically mean a project can’t proceed. 

Options could include reviewing capacity requirements, phasing installations or exploring alternative approaches.

Collaboration between Perth and Kinross Council and SSEN helped identify a solution involving substation upgrades, enabling projects to move forward despite the challenges encountered.