How should SOC be managed prior to FCR delivery?

The technical requirements state: "When providing reserve from LER entities, the SOC must be close to 50% at the start of a period of symmetrical provision, and close to 0 or 100% at the start of a period of asymmetrical provision."

A "period of provision" refers to a continuous period of FCR delivery spanning one or more hours. A new delivery period for an FCR product begins when the activated volume of that product increases compared to the previous hour.

The values 50%, 100%, and 0% refer to the percentage of the energy storage capacity required for FCR delivery.

• In symmetrical delivery (i.e. FCR-N or FCR-D in both directions), energy storage capacity equivalent to at least 1 hour × activated FCR-N volume and 20 minutes × activated FCR-D volume must be available in both directions.
• In asymmetrical delivery of FCR-D, energy storage capacity equivalent to at least 20 minutes × activated FCR-D volume must be available in the relevant direction.

In the special case where the activated FCR volume increases from a non-zero value—i.e. the actor has delivered the same FCR product with a smaller volume in the previous hour—the actor may deviate from the SOC requirement if they can demonstrate that the deviation was caused by FCR delivery during the previous delivery period.

Example:

The actor is activated for 10 MW FCR-D up from 05:00–12:00, 5 MW from 12:00–14:00, and 10 MW from 14:00–18:00.

This results in one delivery period from 05:00 to 14:00, and a new delivery period from 14:00 to 18:00.

The general rule requires that SOC at 05:00 must be at least 10 MW × 1/3 h = 3.3 MWh, and SOC at 14:00 must also be at least 3.3 MWh.

However, if FCR-D up is activated at 13:55 and the NEM function has not yet restored SOC to 3.3 MWh by 14:00, the actor is not required to take corrective action—even though the SOC at the start of the new delivery period does not meet the requirement—because the deviation is due to FCR-D up delivery during the previous period.