In implementing the provisions of Article 18, of Legislative Decree No. 210/2011, ARERA - with Resolution No. 247/2023 - introduced the Mechanism for the Procurement of Electric Storage Capacity ("MACSE"), approving the criteria and conditions for its operation, at the proposal of Terna, in order to regulate the procurement of storage capacity by the grid operator.
The widespread diffusion and incidence of energy production from renewable sources has made the introduction of a storage system for energy production and, therefore, centralised storage capacity essential to ensure flexibility and maximise the use of renewables.
The Mechanism, the rules of which Terna published on 22 October 2024, subject to the approval of the Ministry for the Environment and Energy Security with Ministerial Decree No. 346 of 10 October 2024, is based on the opportunity of entering into standard contracts for the procurement of electricity storage capacity with counterparties selected through competitive procedures, who receive a determined premium expressed in euro/MWh per year: in exchange for the premium, the awarded producer only has to make the contracted capacity available to third parties who have purchased, through Terna, the so-called time-shifting products, i.e., the right to store the energy produced at a specific time in one or more storage plants that were awarded the auctions in the previous phase, and then feed it into the grid at a later time.
These standard contracts prescribe specific obligations for the subscribers, i.e. (i) the actual realisation of the committed storage capacity within the terms provided for by the same contract; (ii) the obligation to make the committed storage capacity available to Terna, for the entire delivery period, in order to allow third-party market operators to exercise time-shifting contracts (iii) the obligation to make available to Terna on the Dispatching Services Market ("DSM"), for the entire delivery period, individually or through aggregates defined by Terna in the Grid Code, the committed storage capacity, complying with the minimum technical performance defined in the contract and the economic constraints.
As mentioned above, therefore, in order to enter into standard contracts, Terna organises special competitive procedures, periodically making available incremental capacity quotas to guarantee the availability of certain quantities of electricity storage in different and future periods, taking into account various variable components: such competitive procedures may only be attended by storage facility owners who meet appropriate subjective and objective requirements, but not limited to.
1.1 About the guarantee system
As part of the above-mentioned competitive procedures, in compliance with the provisions of the ARERA Resolution, Terna organises and manages a system of guarantees to which the participants are required to join, under penalty of being excluded from the same procedures or preventing the participant from proceeding with the stipulation of the standard contract for the procurement of electricity storage capacity. This guarantee system consists of (i) pre-auction guarantees; (ii) post-auction guarantees; and (iii) the guarantee fund.
1.1.1. Pre-auction guarantees
Pursuant to the provisions of Chapter II of the Terna Rules, for each auction the participant must, at least 40 (forty) days prior to the date of execution of the auction for which it intends to qualify the storage system, provide a pre-auction guarantee in an amount equal to the sum of
(i) the qualified capacity[1] of each qualified storage system, expressed in MWh;
(ii) the reserve premium[2] of the open auction to the reference technology with the shortest planning period[3] among those admitted to the competitive procedure;
(iii) a percentage equal to 10 percent.
Said pre-auction guarantee, in the form of a non-interest deposit, will be returned by Terna to each successful participant within 15 (fifteen) days from when Terna sends a countersigned copy of the contract and/or implementation agreement, and to each unsuccessful participant within 15 (fifteen) days from notification of the auction results.
If the assignee participant fails to fulfil the obligations of the assignees identified by Terna, and/or if, following specific checks carried out prior to the signing of the contract and/or the implementation agreement, it emerges that the declarations made and/or the documentation provided are not truthful, Terna may enforce the pre-auction guarantee provided by the participant.
1.1.2. Post-auction guarantees
In the same manner as the pre-auction guarantee, for each contract, the successful participant shall, within 15 (fifteen) days from the communication of the auction results, set up or supplement one or more post-auction guarantees, for a total amount equal to the sum between:
(i) the committed capacity[4] of each contracted storage system, expressed in MWh;
(ii) the reserve premium of the open auction to the reference technology with the shortest planning period among those admitted to the competitive bidding process in which the storage system was contracted;
(iii) the number of years, rounded down, of the planning period of the reference technology with the shortest planning period among those admitted to the competitive bidding process in which the storage system was contracted;
(iv) a percentage equal to 15 percent.
This post-auction guarantee, in the form of a non-interest deposit or a first-demand bank guarantee, will be returned by Terna, at the request of the assignee, following the complete settlement of the economic items arising under the contract and related implementation agreements.
Even in the case of post-auction guarantees provided by the assignee, if the latter fails to fulfil its payment obligations under the contract and related implementation agreements, Terna may enforce the post-auction guarantee provided by the assignee.
1.1.3. The guarantee fund
For each contract stipulated with Terna, the assignee is obliged to pay to Terna, within 15 (fifteen) days from the communication of the auction results, a contribution to the guarantee fund equal to the sum of the products between:
(i) the committed capacity of each contracted storage system, expressed in MWh;
(ii) the reserve premium of the open auction to the reference technology with the shortest planning period among those admitted to the competitive procedure in which the storage system was contracted;
(iii) a percentage equal to 15 percent.
The contribution to the guarantee fund, like the pre and post-tender guarantees, in the form of an interest deposit, will also be returned, at the request of the assignee, following the complete settlement of the economic items arising from the contract and its implementing agreements.
Terna's recourse to the guarantee fund is subject to the prior enforcement of all post-auction guarantees set up by the assignee under the contract to which the performance refers, resorting, in an orderly manner, first to contributions to the guarantee fund paid by the defaulting assignee, then to contributions to the guarantee fund paid by the other assignees.
1.2. The first auction
On 7 March 2025, through an appropriate notice for operators, Terna announced the timeline for the first MACSE auction: in fact, the auction for 2028 for the forward procurement of new storage capacity related to lithium-ion batteries and electric storage technologies other than lithium-ion batteries and hydro storage will take place on 30 September 2025.
Therefore, according to the schedule set by Terna itself, participants are required to apply for admission, in the manner defined by Terna, by June 3 and submit the necessary data and documentation on the MACSE portal by July 17, with payment of the deposit as a pre-auction guarantee by August 21 and uploading of the authorization documentation by the following August 26.
As an estimate, the current authorized capacity is expected to be about 9 GWh, thus below the demand of 10 GWh, but still having to consider that all finally authorized plants will be able to participate by the end of August 2025.
The above and other aspects related to investments in Storage and the associated cash flows in the context of bankability will be discussed with our guests at the conference BESS: profili di bancabilità tra regole e mercato, to be held at our Milan office. Through the link you can register. Places are limited and we suggest you register as soon as possible.
[1] Pursuant to Article 2, para. 1, letter i) of Terna's MACSE Regulation, for each storage system, this is the capacity, expressed in whole MWh values, that Terna qualifies for auction.
[2] Pursuant to art. 2, para. 1, letter aaa) of Terna's MACSE Regulation, this means the maximum value that can be taken by the adjusted premium (i.e., for each storage system, the amount equal to the product between the premium and precise coefficients referred to in the same regulation adopted by Terna), as defined by the Authority in relation to a competitive procedure.
[3] Pursuant to Article 2, para. 1, letter jj) of Terna's MACSE Regulation, this means the period, defined in the technical report, between the date of communication of the auction results and the start of the delivery period (i.e., the period during which the contracted storage system is subject to the availability obligation and the restitution obligation, beginning on January 1).
[4] Pursuant to Article 2, para. 1, letter g) of Terna's MACSE Regulation, for each storage system is the capacity, expressed in whole MWh values, that is contracted as a result of participation in the auction.
