The Macse auction with a 2029 delivery year has reached its most significant operational milestone ahead of the tender. Terna has published the national quota along with the minimum and maximum thresholds allocated to individual zones of the electricity system, fully confirming the requirements outlined by the transmission system operator on 28 May. The overall volume remains set at 16 GWh.
The announcement therefore does not alter the size of the initial schedule disclosed in the spring, but makes available to the market the territorial parameters that storage projects will have to navigate in the auction scheduled for 24 November. It is a step that reduces uncertainty for developers, financiers, and storage system suppliers: capacity demand is not being revised at the last minute, and the geographic distribution of the auction remains the one mapped out months ago.
In Terna’s design, the largest share of flexibility is allocated to the Sud e Calabria zone. For this area, the minimum quota is 3 GWh, while the maximum reaches 11.5 GWh—the highest figures among the evaluated zones. This is by no means a neutral indication regarding the location of investments. Storage capacity is called upon to operate where the grid most urgently needs to absorb, inject, and time-shift electricity, and the geographical scope of the procedure forms an essential part of the economic signal sent to operators.
What the quotas define
Macse is the Meccanismo di approvvigionamento di capacità di stoccaggio elettrico. Through this mechanism, Terna identifies and procures storage resources deemed necessary for the system, aiming to support the expansion of renewable generation and maintain grid adequacy and security over the medium to long term.
The 16 GWh figure must be read as energy storage volume, not merely as an indication of the instantaneous power capacity of the facilities. In practical terms, it expresses how much energy the selected assets must be able to store and make available under the rules of the mechanism. In a market dominated by the growth of solar PV and wind, this distinction is critical: generating electricity from renewable sources does not necessarily mean having it available at the hours and grid nodes where it is needed.
The minimum and maximum limits per area are specifically designed to prevent selection from being driven solely by short-term economic convenience or the concentration of supply in just a few areas. Storage capacity installed far from the points where the grid experiences the greatest demand can have a different value for the system compared to a technically equivalent facility located in the required area. For this reason, Terna combines a national target with geographical constraints.
The confirmation of the figures published in May takes on added significance as the auction draws near. After months of permitting development, technical definition, and financial structuring of projects, a change in quotas could have altered operators' assessments. The decision to keep the framework unchanged instead provides a more stable foundation for the November 24 bids, without eliminating the competitive uncertainties that will only become clear with the outcome of the procedure.
The premium set by ARERA and the test for the supply chain
Another element already established concerns the reserve premium. In September, ARERA set it at 27,000 euros per MWh, raising the value from the 22,000 euros per MWh that emerged during the July consultation. It is one of the tender's core economic parameters, as it helps define the framework within which participants can formulate their bids.
The level of the premium should not be confused with the outcome of the auction or with revenue automatically granted to all projects. Competition will show which economic conditions operators deem sustainable to build and deliver the required capacity. For this very reason, the procedure will be closely monitored across the entire supply chain: battery manufacturers, system integrators, EPC, developers, investors, and parties active in plant operations.
Dedicated storage auctions have become a testing ground for the transformation of the Italian electricity system. Indeed, the penetration of variable renewables alters both network flows and the profile of flexibility demand. During hours of high solar generation, the value of resources capable of absorbing energy can increase; in other time slots, that same energy can become useful if fed back into the grid. Storage does not single-handedly replace infrastructure upgrades, market rules, or other flexibility tools, but it can help bridge generation and consumption across different timeframes.
The central focus placed on Sud e Calabria must be viewed from this industrial and grid perspective. Facility siting decisions do not depend solely on land availability, proximity to new renewable plants, or the speed of permitting procedures. Signals from the national transmission system operator and the ability to connect new infrastructure without exacerbating local constraints also play a critical role. The quotas make this hierarchy of needs explicit.
From requirements to delivery in 2029
The timeline clearly separates the selection phase from the point at which capacity must become available. The auction will take place in 2026, while delivery is scheduled for 2029. Between these two dates lies the most complex phase for the selected projects: completing development, permitting, grid connections, equipment procurement, construction, and commissioning in line with the commitments made.
This is where the gap between an announced pipeline of initiatives and genuinely operational infrastructure is measured. The storage sector can rely on mature technologies and an expanding supply chain, but it remains exposed to tangible variables: connection timelines, site availability, technical requirements, contractual conditions, and companies' ability to turn a project into an active construction site on schedule. The Macse auction does not automatically resolve these issues; however, it defines the capacity perimeter from which deployment must begin.
For the electricity system, what is at stake is the ability to plan sufficiently in advance the tools needed for a grid increasingly powered by non-programmable sources. The fact that Terna has not modified the national requirement and territorial quotas compared to May provides continuity to this planning. The next truly significant data point will be the auction outcome: it will reveal how much supply comes forward, under what conditions, and to what extent the market will be able to respond to the signal mapped out by Macse.
Until then, the figure to watch remains 16 GWh, along with the weight assigned to Sud e Calabria. These figures do not yet represent built batteries or energy already available to the grid, but they define the institutional demand that will guide upcoming investment decisions in Italian storage.
