22 / 272
22 |
TAR NC Implementation Document – Second Edition September 2017
Chapter III ‘Reserve prices’
Scope: IPs
Application date: 31 May 2019
Reserve prices serve as a floor in the relevant capacity auction. The previous Chapter
sets out how to calculate a reference price; this Chapter addresses the next steps for
defining the reserve prices: the capacity-based transmission tariffs used in the
auctions.
The reserve price for firm yearly capacity is equal to the reference price. The reserve
prices for firm non-yearly capacity products involve the application of formulas with
multipliers
based on the reference price and, optionally,
seasonal factors
.
Reserve price = time proportion of reference price x multiplier x seasonal factor
The TAR NC defines the ranges for the respective multipliers, and a detailed
methodology for calculating seasonal factors.
\\
The range for quarterly and monthly multipliers is between 1 and 1.5.
\\
The range for daily and within-day multipliers is between 1 and 3.
The range for daily and within-day multipliers may be extended in ‘
duly justified
cases
’ to less than 1, but higher than 0, or higher than 3.
The same ranges apply to the arithmetic mean over the gas year of the product of
each separate multiplier and its seasonal factor.
Depending on ACER’s recommendation by 1 April 2021, the range for these
multipliers may narrow to between 1 and 1.5 by 1 April 2023.
The reserve prices for interruptible capacity products involve discounts to the
reserve prices for the corresponding firm capacity products. There are two alterna-
tives for such discounts:
\\
An
ex-ante discount
calculated upfront, based on the formula set out in the
TAR NC, using the probability of interruption and the estimated economic value
of the product;
\\
An
ex-post discount
, which constitutes compensation paid to network users af-
ter the actual interruption has occurred; such a discount is an option only if
physical congestion did not prompt any interruptions in the preceding gas year.
The multipliers, seasonal factors and discounts are subject to NRA
consultation
with adjacent NRAs and relevant stakeholders
every tariff period
.