Here’s a breakdown of what each of the merit order stack parameters cover.

The market operator defines the market location - which can be from country wide to street level - including one or many locations.

Start Date and End Date specify the date of the request.

The Time element allows market operators to specify the time window, which can be for specific hours of the day.

For example, if the market is configured to run weekly, the Market Operator could request:

This request lasts for seven days, between the hours of 16:00 and 19:00. The request doesn't apply for hours outside of this range, which means that it isn't continuous.

Days of the Week allows market operators to specify the days of the week for which the request applies, within the date range specified above.

The days of the week are defined as part of the market.

Using the example time window as above:

The market operator can then specify Days of the Week, Monday to Sunday, within this date range.

For example, if the market specifies Monday, Wednesday, Friday, Sunday the request will then cover the following dates and times:

The Utilisation Ceiling Price parameter specifies the maximum utilisation price that the Market Operator is willing to pay for the flexibility service, where applicable.

If the utilisation price you require is higher than the price ceiling indicated by the Utilisation Ceiling Price parameter, you will not be awarded the contract.

In markets that pay for both availability and utilisation, the Availability Ceiling Price parameter specifies the maximum availability price that the Market Operator is willing to pay for the flexibility service, where applicable. If the availability price you require is higher than the ceiling indicated by the Availbility Celing Price parameter, you will not be awarded the contract.

Total Price determines the order of DERs in the merit order stack. In markets that pay for utilisation only, the Total Price is equal to the utilisation price.

In markets that pay for both availability and utilisation, the Utilisation-weighting factor (%) is used to adjust the importance of the utilisation price component in the Total Price calculation.

This helps market operators account for scenarios where the expected availability hours are higher than expected utilisation hours. The weighting is applied in the following way to calculate the Total Price, which is used to order DERs in the stack:

This adjustment only affects the order in which DERs appear in the stack, not the price they are paid, which is the “Accepted Price”.

The market operator can set the Utilisation-weighting Factor anywhere between 0% and 100% by default. Different factors can be used for different markets.

The flexibility volume parameter specifies the total volume needed. DERs are selected based on their merit order (lowest Total price) until this volume requirement is met.