BSC Modification P455 on On-Site Aggregation for Third Party Access implemented in Great Britain

Elexon's BSC Modification P455 introduces On-Site Aggregation as a method to facilitate Third Party Access on private networks with domestic and small business customers, allowing aggregated sub-meter data to be submitted into Settlement instead of data from Boundary Point Settlement meters. The modification completed the full BSC governance process and was implemented on 24 September 2024 as part of a Special BSC Release, following Ofgem's approval on 17 September 2024.

This changes how settlement data is sourced for private network sites with multiple domestic/small business customers, potentially lowering metering costs and enabling more cost-effective third-party supply arrangements on private networks, which affects supplier participation and metering infrastructure requirements at these sites.

P455 represents a targeted settlement-methodology reform addressing a specific technical barrier: the cost of installing Boundary Point Settlement meters on private networks serving domestic/small business customers under Third Party Access arrangements. By permitting aggregated sub-meter data as an alternative settlement input, the modification reduces metering infrastructure costs and could increase the viability of competitive supply arrangements on private networks (e.g., private wire estates, multi-occupancy developments). The full governance lifecycle—from Workgroup assessment through Report Phase consultation to Authority decision and Special Release implementation—was completed within approximately 15 months (June 2023 to September 2024), indicating a relatively streamlined SCR-exempted process (Ofgem granted an SCR suitability exception on 9 October 2023). As the modification is now implemented, the primary forward-looking analytical interest shifts to monitoring uptake and any operational or data-quality issues arising from aggregated sub-meter submissions in Settlement.

Balancing and Settlement Code (BSC) Modification P455; approved under Ofgem Authority decision; implemented via Special BSC Release

—

Primary sources