11kV Network Heat Map

Since the introduction of increased Renewable Obligation Certificate (ROC) incentives for small scale generation in April 2010, there has been a large increase in the amount of small scale generation either connected to, or committed to connect to, the 11kV network.

This increase in small scale generation is leading to increased 11kV connection costs and the requirement for 33kV reinforcement work to facilitate generation from the 11kV network to the 33kV network.

The main purpose of the network heat map is to provide guidance on the capability of the 11kV network to accept further small scale generation.

An online mapping tool of the 11kV network is also available to view.

As generation connection costs, and potential 33kV reinforcement costs detailed below, are significantly influenced by the quantity of generation already committed, the network heat map is intended to provide a simple visual representation of those areas now either at or reaching saturation point.

While all reasonable care has been taken to ensure the accuracy of the Network Heat Map, it should be noted that this map will change over time as further generation is committed and should therefore be used as a guide only.

Actual connection costs can only be established following receipt of a formal application by carrying out a detailed network analysis on the specific circuit to which the generation will connect.

Primary substations requiring 33kV Investments

Due to the high level of small scale generation either connected or committed to connect, 33kV investments are now required to facilitate additional generation on the 11kV network, particularly during periods of low electricity demand.

The 33kV investments required are wide ranging and include installation of voltage control equipment to enable reverse power flow at the primary substations, replacement of older transformers and/or tap-change equipment which cannot accept reverse power flow, and in some cases, rebuild of the upstream 33kV networks.

The latest 11kV Network Heat Map updated in February 2015, identifies primary substations where 33kV investment is currently required and those that are likely to require 33kV investment in the near future.

Heat-Map-February-2015 [link opens in new window]. 
Heat-Map-October-2014 [link opens in new window]. 
Heat-Map-August-2014 [link opens in new window]. 
Heat-Map-June-2014 [link opens in new window]. 
Heat-Map-October 2013 [link opens in new window]. 

For the latest information and proposals on how to deal with these 33kV capacity issues, please click here.

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