CER after the GSE rules: what to actually plan for

The operating rules for Comunità Energetiche Rinnovabili (CER, renewable energy communities) have moved from policy debate to the first wave of real projects under the CACER decree (DM 414/2023), which replaced the 2020 transitional scheme and has since been amended.

Framework as of 2 October 2026: Legislative Decree 199/2021, the CACER decree (MASE ministerial decree 414/2023, amended by decree 127/2025), ARERA’s TIAD and the GSE operating rules in the version of 16 July 2025.

This note is for people who have to deliver against a deadline. The GSE operating rules do not describe a plug-and-play incentive: the operational reality sits between "revenue-bearing asset" and "compliance programme". Five things to plan for.

1. The incentive is predictable. The cash flow is not.

The tariff mechanics, once you sit down with them, are predictable: for 20 years the premium tariff follows a formula fixed by the CACER decree, with a base of €60, €70 or €80/MWh depending on plant size, a component that rises when the hourly zonal price falls below €180/MWh, a cap of €100, €110 or €120/MWh, and an uplift for solar PV in Central (+€4/MWh) and Northern (+€10/MWh) Italy. The problem is that the incentive is allocated ex post, on shared energy calculated hour by hour (in each hour, the lower of the energy fed into the grid by the configuration’s plants and the energy drawn by its consumption points), and it depends on every member’s behaviour, not just the plant.

During the year the GSE pays monthly advances on an estimate that assumes a coincidence factor of 0.60 between injection and withdrawal. The actual amount arrives with the true-up, from the following year, calculated on the metering data sent by the grid operators.

The banking question is therefore not "is the tariff real?" but "how much shared energy do we assume for this membership profile?" The answer varies materially by use case. A residential-heavy CER looks different from a CER anchored by the continuous load of an industrial SME: large companies cannot be members of a CER.

2. Governance matters earlier than you think.

The CER statute (who admits new members, how surplus is distributed, how the legal entity handles disputes) is not just a compliance artifact, even though the GSE operating rules set its essential elements, from open and voluntary participation and the right to exit to how the excess premium tariff is allocated. It is the architecture that determines whether the project can be financed, expanded or transferred.

A generic template copied from an aggregator needs reworking before the first serious member joins. Better to design it once, properly, up front.

3. The ESCo role needs rethinking.

The GSE operating rules allow an ESCo certified under UNI CEI 11352 to act as the CER’s referent (soggetto referente) without being a member, provided it is the producer of a plant in the configuration. In our reading, the commercial case is shifting from "we do everything" to "we do the things that actually require a balance sheet and an engineering team": statute drafting, community engagement, monitoring and reporting tend to move to specialists.

For mid-size ESCos that is good news: they can concentrate on the profitable parts and coordinate specialists for the rest.

4. Data governance is where projects break.

The GSE rules presuppose a configuration kept in order: an up-to-date register of members and connection points (additions and removals of plants and withdrawal points must be notified to the GSE within 120 days), an annual report to the GSE on the benefits and how they were allocated, and separate accounts for each type of contribution. Injection and withdrawal data are sent to the GSE every month by the grid operators; the referent finds them on the GSE portal, hour by hour and point by point, and those are the data the internal allocation should start from. A plant and a member list do not make a CER, from an auditability standpoint.

In our view this is the dimension on which projects will separate. Promoters who treat monitoring as a core part of the project will move faster; those who add it after the fact will spend more time in remediation than in expansion.

5. "One plant, one community" is not a strategy.

It pays to treat the first CER as a proof of concept: one plant, one municipality, one anchor load. What matters is the second one.

The reusable parts (statute, incentive model, monitoring stack, member onboarding) are where the programme compounds: promoters who design for reuse from the start reach the second CER without starting from scratch.

What the GSE does in a CER

The GSE provides the distributed self-consumption service, which a CER accesses through one application per configuration, filed by its referent. In its review it checks the requirements, including that every connection point of the configuration lies in the area of the same primary substation, and only if the outcome is positive does it activate the contract with the referent. It calculates the hourly shared energy of each configuration on the metering data from the grid operators and pays the referent the premium tariff and the valorisation contribution, where due: monthly advances during the year, then the true-up by 15 May of the following year (see point 1). Throughout the incentive period it may audit the configuration through document checks and site inspections, including unannounced ones, to establish that the requirements are met and continue to be met.

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For clarity: Altheon is not an ESCo and does not take the role of referent (soggetto referente) of a CER. If you are setting up a CER, or advising on one, and any of this is relevant to you, write to us.

Sources

Premium tariff, duration, requirements for companies and the threshold on the excess premium: MASE ministerial decree 414 of 7 December 2023 (CACER decree) ↗, articles 3 and 4 and Annex 1, as amended by MASE ministerial decree 127 of 16 May 2025 ↗. Statute, members, referent, one application per configuration and its review, advances and true-up, reporting, metering data, changes to configurations and audits: the GSE CACER operating rules (version of 16 July 2025) ↗, Part II, sections 1.2.2, 1.2.2.1, 1.2.2.2, 1.2.2.3, 2.1.3, 2.2.2, 2.2.2.1.1, 2.2.2.1.2, 2.2.2.1.3, 2.2.2.2.2, 2.2.3, 2.3 and 2.4.1; chapter 3 of Part II governs the transition from the transitional scheme of article 42-bis of Decree-Law 162/2019 to the CACER decree. Shared energy and the tasks of the GSE in the distributed self-consumption service (application through the referent, check of the requirements and contract, calculation of shared energy, contributions to the referent, data from the grid operators, audits): TIAD, Annex A to ARERA resolution 727/2022/R/eel of 27 December 2022, as amended by resolution 15/2024/R/eel ↗, article 1, letter t), and articles 4, 6, 7, 8 and 12. Shareholders and members of a CER: Legislative Decree 199 of 8 November 2021, article 31 ↗ (text in force, consulted on 2 October 2026).

Update of 2 October 2026: the framework is no longer described as final, because the CACER decree was amended by decree 127/2025; the incentive is described on hourly shared energy, with estimated advances and a true-up; the premium tariff parameters, the mandatory elements of the statute, the exclusion of large companies, the case in which an ESCo can act as referent and the data obligations have been added; market observations without a source are now stated as our reading or removed, including the 12-month forecast; sources have been added.

Update of 3 October 2026: added the section "What the GSE does in a CER", with its sources. This article is not legal advice.