27 September 2021

On 1st October 2021 modification UNC0745S will be implemented for short-term GB capacity auctions, as per the Joint Office notice published 20th September 2021.

This modification mandates the use of existing bid parameter functionality in Gemini / Gemini Exit for short-term GB capacity auctions listed below. 

For Users participating in these auctions, price AND capacity (volume) Upper Limit parameters must be in place prior to auction participation, from 00:00 1st October 2021*.

Our recent analysis shows a number of Users don’t yet have both parameters in place – it’s important that Users have both price AND capacity parameters in place prior to 1st October 2021.

Without both parameters in place, an error message will be generated at the point of bid submission and participation will not be possible until bid parameters are set up for the relevant auction. It is the responsibility of all Users who participate in short-term auctions to set up bid parameters ahead of UNC0745S implementation. Neither National Grid nor Correla/Xoserve are able to do this on behalf of Users.


 * To clarify, using the example of within-day Firm, bids placed up to 23:59 31st September 2021 for gas day 1st October 2021 will not be subject to mandatory parameters, though bids placed from 00:00 1st October 2021 for gas day 1st October 2021 (and onwards) will require these to be in place prior to auction participation.


Short-term capacity auctions mandating the use of Bid Parameters from 1st October 2021

Gemini Entry

  • Day-Ahead Daily Entry Capacity (DADSEC)
  • Within-Day Daily Entry Capacity (WDDSEC)
  • Daily Interruptible System Entry Capacity (DISEC)

Gemini Exit

  • Day-Ahead Daily Exit Capacity (DADNEX)
  • Within-Day Daily Exit Capacity (WDDNEX)
  • Daily Off-Peak Exit Capacity (DONEX)

What do I need to do and by when?

By 00:00 1st October 2021, Users who participate in short-term GB auctions (listed above) need to ensure both price AND capacity (volume) Upper Limits are in place in Gemini / Gemini Exit, prior to participation in the relevant auction.

Screen pack – A detailed technical screen pack outlining all system changes (including simplifying the bid parameters in Shipper/User Preferences screens) can be found  here - UNC0745 - System Screen Pack

Overview  – A high-level guide on bid validation parameters, prior to the screen pack changes, can be found here:  September 2020 Ops Forum Pack (slides 60-70).

Please note: to further support this change we have granted Gemini (Entry) Shipper Analysts (role IGMS020) the ability to set up bid validation parameters (previously restricted to Shipper “Super Users“, role IGMS019). This is in line with Gemini Exit, in which all Users can set up parameters.

If you are unsure as to whether you have bid parameters (Shipper/User Preferences) set up in Gemini/Gemini Exit, or need any further information on this change, please contact capacityauctions@nationalgrid.com (re “MOD 745 query”).

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