STA Launches Industry’s First-ever Best Practice Manual On Distribution Network Outages

The Solar Trade Association (STA) today launched the UK solar industry’s first-ever best practice manual on the management and mitigation of network outages for Distribution Network Operators (DNOs), and for solar farms connected to their networks.

Constraints on PV generation due to both planned and unplanned network outages, typically for maintenance work, are the most significant cause of lost power production, and hence lost revenue, for solar generators in the UK. Between 2015 and 2017, these generation losses were equivalent to approximately 1% of total installed solar capacity, or £10m per year in foregone revenues across the solar industry.

STA Chief Executive Chris Hewett said:

“The UK electricity system is in the midst of a period of profound and unprecedented transformation, with important implications for managing the distribution networks in particular.

“With nearly 13GW of solar capacity on the system and strong potential for growth in the next decade, it is important that solar generators are managed as efficiently as possible. This new manual will help DNOs and the industry to understand how best to do that and we hope all DNOs will want to adopt the recommendations in the manual as the industry standard as quickly as possible.”

This technical document was authored by power systems engineering consultancy EA Technology and sponsored by Quintas Energy, with additional support provided by Lightsource BP, Wise Energy, Foresight Group and Bluefield LLP. The manual has now been officially endorsed by the DNOs Western Power Distribution (WPD) and UK Power Networks (UKPN), both of whom were actively engaged throughout the process and contributed to developing the best practice guidance.

The STA will be presenting the document to the other DNOs, the Energy Networks Association and to relevant stakeholders, with the goal of encouraging the adoption of the best practices described, and of enabling broader participation in developing future editions of the manual.

The manual ensures that for the first time both generators and network operators can access the best guidance advice on:

The legal and regulatory requirements that the DNOs must satisfy and the process they undertake to develop an annual programme of planned outages
The relative impact of constraints for solar generators at different times of the year and in all different areas of the country
Responsibilities and optimal processes for information-sharing between parties and notification of network outages, including a detailed glossary of terminology for physical network infrastructure

The guide also includes several real-life case studies, illustrating how advance notification of planned outages enabled PV generators to take steps to remain connected whilst the grid repairs or upgrades took place, and thus avoid the loss of hundreds of thousands of pounds.

One case study describes how a 5 MW solar farm was due to be constrained for 24 days over April and May of this year, resulting in a potential loss of up to 450 MWh. Upon notifying the site owner, more than two months before the network upgrade was scheduled to begin, the DNO provided an option to reduce the outage affecting the site by installing a 33kV isolator on the affected line, reducing the potential outage length from more than 3 weeks to just 2 days. In this case, the advance notice and detailed information provided by the DNO on mitigation options enabled the owner to make an informed decision and avoid nearly all the potential impact of the constraint.

The STA’s Best Industry Practice Manual – Management of network constraints on solar PV generation (Version 1.0) is freely available for download on the STA website.

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