Questions and answers on TERRE and Wider Access

We have compliled a number of questions and answers about participating in the TERRE and wider access arrangements. These are not exhaustive but will go some way in explaining key facts that will help you understand how the new arrangements will impact interested companies.

If you have any other questions that are not listed here, please contact

How can I Participate in TERRE?

You can participate in TERRE through the BSC framework in a number of ways, as outlined below:

  1. A Virtual Lead Party (VLP) may register Secondary BM Units for the purposes of bidding into the TERRE product. One function of Secondary BM Units is to allow Virtual Lead Parties to aggregate a number of sites across multiple Suppliers in order to provide balancing services. Therefore, Secondary BM Units may be a single site, or a collection of sites whereby the minimum generation level exceeds 1MW. Secondary BM Units will also be able to be bid into the Balancing Mechanism by the VLP.
  2. A Supplier may register Additional BM Units for the purposes of bidding into the TERRE product, alongside bidding into the BM as per the current arrangements. Further, current arrangements within the BSC allow a Supplier to aggregate a number of sites, within an Additional BM Unit, so long as these sites are all within that Supplier’s portfolio. This is commonly known as a Supplier aggregator function.
    Should a Supplier wish to aggregate a number of sites that have different Suppliers, it will need to register as a VLP and hence participate in TERRE through Secondary BM Units in these instances.
  3. A Trading Party that is not a Supplier may use its existing BM Units for the purposes of bidding into the TERRE product, alongside bidding into the Balancing Mechanism as per the current arrangements. However, a Trading Party that is not a Supplier cannot aggregate sites. Should a Trading Party that is not a Supplier wish to aggregate sites, they would have to register as a VLP.

Why has the go live of Project TERRE been delayed?

Project TERRE was due to launch across nine European countries this autumn. We were made aware on 21 June that National Grid ESO has raised a derogation request with energy regulator Ofgem to delay its participation in the Project TERRE balancing product to no later than December 2020.

The request has been made because French electricity transmission system operator RTE has announced that it will not go live in December 2019, which means there will not be a market in which GB can participate.

What is ELEXON’s view on the delay?

We are committed to supporting wider market access to the GB Balancing Mechanism (BM) and GB market participation in TERRE. We still intend to make wider BM access available this year, regardless of whether GB participation in TERRE is deferred.

This is to ensure that independent aggregators have access to the GB BM (as part of, and set out in Modification P344 ‘Project TERRE implementation into GB market arrangements).

ELEXON will continue to work closely with National Grid ESO to ensure that we play our part in enabling GB’s participation in Project TERRE on the date approved by Ofgem.

Can other BSC parties have aggregated Secondary BMUs?

Only a VLP is able to register Secondary BM Units (i.e. aggregate Half Hourly Metering Systems (HH MS) in order to provide balancing services to RR & BM whilst not being responsible for settling the volumes from those meters in regards to contracted v metered volumes).

A Supplier can register an additional BM where they can aggregate HH MS in order to provide balancing services to TERRE and BM, but remains responsible for settling the volumes from those meters in regards to contracted and metered volumes).

Can I register in multiple roles?

A BSC Party can have multiple roles under the BSC. For example, a Supplier can qualify as a VLP (and vice versa) and under, the VLP role, register Secondary BM Units

Where can I find a list of all the charges VLP face?

The Schedule of Main and SVA Specified Charges guidance note detail the costs and charges for 2019/2020. You can find the guidance on the following webpage:

Can VLPs register assets on behalf of a third party (i.e. a client’s assets)?

A VLP can allocate a client’s asset metering systems (MPAN or MSID) to a Secondary BM Unit where they can aggregate the changes in those client’s sites loads or distributed generation output for sale in the Balancing Mechanism or Replacement Reserves markets. A VLP does not need to be the asset owner.

Can VLPs use a trading agent to participate in BM and TERRE?

The obligations under the BSC (and CUSC) remain with the registered Party. How Parties choose to ensure compliance is a business decision. To clarify as a VLP you will not be able to ‘trade’ on the wholesale market. Through the BSC, a VLP can offer balancing services to TSO for the BM and RR markets.

What are the penalties for over and under delivery in TERRE, and how does this compare to those in the BM?

For over delivery (in the BM or TERRE), there is no financial penalty in the trading charges (though you will have expended resources at site that you are not being paid for).

For non-delivered volume (BM or TERRE), a party will be exposed to the imbalance price. An additional non-delivery charge may be levied if the party is benefitting from non-delivery (e.g. the party paid £50, but the imbalance price is £40, which results in a £10 gain. In this case, the party will be levied an additional charge of £10).

Is there a limit to the size in MW of secondary BMUs?


In the case the BMU is larger than 50MW or 100MW, are there any additional requirements on the BMU (metering etc.)?

Not under the BSC.

What data does a VLP need to send to Elexon for a Secondary BMU on a daily basis?

For their Secondary BM Units, VLPs do not need to send FPN nor live generation data to ELEXON. BSC does require however that a VLP is compliant with the Gridcode (administered by the NGESO) which has a number of data requirements that a VLP needs to send to NGESO.

  • Please refer to Section Q for BSC requirements.

For NGESO requirements please refer to Grid Code (note some will be the same as BSC).

BSC does require that a VLP inform us of the MSID (via MSID Pairs) that they wish to allocate to a Secondary BM Unit prior to offering Balancing Services. After delivery of balancing Service the BSC requires a VLP send ‘Delivered Volumes’ (i.e. the physically delivered balancing volumes) per site.

  • Please see Section S and BSCP602 for process details

When will relevant data be published?

The P344 solution includes provisions for TERRE data (relating to balancing service providers in GB) to be published on the BMRS:

  1. Following Gate Closure for each auction period, National Grid will send details of Replacement Reserve Bids to BMRA, who will publish them on the BMRS. The legal text allows up to fifteen minutes for National Grid to provide this data.
  2. By thirty minutes after Gate Closure for each auction period, National Grid will send the results of the auction (as received from the LIBRA platform) to BMRA, who will publish them on the BMRS. These results include price and MW level data for all the Replacement Reserve Activations issued to GB balancing service providers; the Level of GB Need Met; and flows scheduled by LIBRA on Interconnectors.
  3. BMRA will also include the results of the auction in the indicative imbalance prices, published (as currently) within 45 minutes of the end of the Settlement Period


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