"Utilisation Payment" means any payment in respect of Sustain, Secure or Dynamic services calculated in accordance with 2.2 of this below, or any payment in respect of Restore services calculated in accordance with 3.1 below;

"Utilisation Settlement Period" means each full one (1) minute period during a Utilisation event, as described in 1.2 below, with the first Utilisation Settlement Period being the minute in which the Response Time ends.

1 GENERAL

1.1 For Secure and Dynamic services, there are two primary payments: Availability Payments and Utilisation Payments. For Sustain and Restore services, there is one payment: the Utilisation Payment. Availability Payments are paid for every Accepted Availability Window. Utilisation Payments are made for every instance of Utilisation.

1.2 Availability Payments and Utilisation Payments are calculated at a different granularity called the Availability Settlement Period and the Utilisation Settlement Period. The constants used to convert between MWh values and the individual time segments are (SPu) and (SPa), which correspond to the fraction of an hour for Utilisation and Availability. The Utilisation Settlement Period is 1 minute. The Availability Settlement Period is 30 minutes i.e.:

SPu = 1/60 and SPa = 0.5

1.3 In respect of each Dispatch Group there are three key values:

• a)The Contracted Capacity (CCs), given in MW;
• b)An Utilisation Cost (UCs), which is the price per MWh for Utilisation. The Utilisation Cost for each of the Company Dynamic Services, the Company's Secure Services and/or the Company's Restore Services for each Zone shall be as set out in the relevant Contract Award;
• c)An Availability Cost (ACs), which is the price for Availability in respect of an Accepted Availability Window at a Dispatch Group. This is a price per MW per hour of Availability. The Availability Cost for a CMZ shall be as set out in the relevant Contract Award.

1.4 Payments are calculated on a month-by-month basis. The calculations in this document determine the Utilisation Payments and the Availability Payments due for a Dispatch Group for a given month.

1.5 For the Secure and Dynamic Services, after each operational month, (m), there is a list of Accepted Availability Windows and a list of Events, which are written as (APm) and (Em). The top-level calculations will loop through these lists, but the bulk of the work is performed for an individual Accepted Availability Window and an individual Event.

2 SUSTAIN, SECURE AND DYNAMIC SERVICES

2.1 Availability Payments (Secure and Dynamic Services)

2.1.1 Availability Payments for an Accepted Availability Window are determined as the sum for all Availability Settlement Periods in that Accepted Availability Window, based on binary values of Dispatch Group availability during each Availability Settlement Period.

2.1.2 STaw and FTaw are written for the start and finish time of the given Accepted Availability Window.

2.1.3 The raw Availability Payment given to a Dispatch Group for an Accepted Availability Window is as follows:

Where the Availability Cost is a payment per MW per hour:

SSEN Flexibility Services