Grid-Approved Solar Italy | TICA, STMG & Terna pathway

Grid-Approved Solar Projects in Italy: TICA, STMG and Terna pathway guide

Grid connection is, in fact, the single most material risk driver in Italian utility-scale solar acquisitions. Even when permits are fully secured, an unresolved grid connection pathway can delay COD by 12-24 months and, consequently, undermine bankability. Therefore, understanding the Italian grid connection process — and specifically the TICA, STMG, STMD workflow — is essential for any institutional investor evaluating Italian PV opportunities.

RTB.SOLAR operates as an independent Italian advisor. Specifically, we support investor clients during the grid connection due diligence: pathway identification, milestone verification, Terna/DSO records check, residual constraints analysis. However, we do not act as the technical advisor of record on grid matters. Instead, we coordinate with the technical advisor commissioned by the client.

🔌 What this page covers: the 5 milestones of the Italian grid connection process (STMG, STMD, TICA, payment, energization), the technical difference between Terna and DSO scope, typical connection costs by voltage level, and grid bottleneck zones in 2026. For the parallel authorization pathway see fully authorized solar projects in Italy.

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Grid-approved solar projects Italy - TICA STMG Terna pathway

Why grid connection is the critical bankability gate

Investors often experience “project slippage” not because permits are missing, but because the grid connection pathway is uncertain, constrained, or simply slower than expected. In particular, three recurring patterns emerge in Italian utility-scale PV:

  1. STMG accepted but TICA not yet signed: the investor inherits a project marketed as “grid-approved” but, in fact, the connection contract is not finalized. As a result, costs and timeline remain uncertain.
  2. TICA signed but grid operator works delayed: even when the asset side is ready, the Terna or DSO side (substation upgrades, line reinforcements) can be the critical path. Consequently, COD slippage is significant.
  3. Grid zone constraints: even when individual project status is clean, the broader zona di rete may have congestion that limits effective injection. Therefore, due diligence must extend beyond the individual TICA to the systemic context.

For bankability purposes, lenders typically require all three issues to be addressed. Otherwise, the asset cannot be safely classified as investment-ready, regardless of the permitting status.

The Italian grid connection process: 5 milestones

The Italian grid connection process follows a regulated workflow defined by ARERA (the Italian energy regulator) and managed operationally by Terna for HV connections and by the local DSO for MV connections. Specifically, the process develops across 5 sequential milestones:

🔌 Milestone 1 — Richiesta di connessione

The proponent (developer) submits the connection request to the grid operator. Specifically, the request goes to Terna for HV (alta tensione) connections, typically required for projects >10 MWp. By contrast, the request goes to the local DSO (e-Distribuzione, Areti, Acea, etc.) for MV (media tensione) connections.

Typical duration: request is processed within 60 working days. Furthermore, payment of the istruttoria fee is required at submission.

🔌 Milestone 2 — STMG or STMD issuance

The grid operator issues the STMG (Soluzione Tecnica Minima Generale) or STMD (Soluzione Tecnica Minima di Dettaglio). In particular, the STMG defines the connection point, voltage level, capacity allocated, indicative costs and required grid works. Additionally, the document specifies whether the costs are at the proponent’s expense or split with the operator.

Validity: the proponent has 45 days to accept the STMG. Otherwise, the request lapses.

🔌 Milestone 3 — TICA acceptance and signature

Once the proponent accepts the STMG, the operator issues the TICA (Testo Integrato Connessioni Attive): a formal connection contract that defines specific costs, payment schedule, deadlines, technical responsibilities, and milestones for grid works. Moreover, the TICA is the legally binding instrument that crystallizes the connection rights.

Action required: the proponent must sign the TICA and pay the first tranche of connection costs (typically 30%) within the deadline. As a result, the connection rights are secured.

🔌 Milestone 4 — Payment progression and grid works

During the construction phase, payment of remaining connection cost tranches occurs against milestones. In parallel, Terna or DSO execute their scope of works: substation upgrade, line reinforcement, switchgear, metering. Furthermore, this stage is often the critical path, especially when a dedicated substation is required.

Typical duration: 12-24 months from TICA signature to grid readiness, depending on the scope. By comparison, projects connecting to existing infrastructure (no new substation) are much faster.

🔌 Milestone 5 — First parallel and commercial operation

When the plant is built and tested, the grid operator authorizes first parallel (primo parallelo): the plant is connected and synchronized to the grid. Subsequently, after final testing and commissioning, the plant reaches COD (Commercial Operation Date). Indeed, this is the date when commercial energy production starts and revenue accrual begins.

STMG vs STMD: what investors need to understand

STMG and STMD are often used interchangeably in marketing materials. However, they have distinct technical implications:

Feature STMG STMD
Full name Soluzione Tecnica Minima Generale Soluzione Tecnica Minima di Dettaglio
Typical applicability Standard procedure for most cases Complex cases requiring detailed engineering
Level of detail General connection solution Detailed engineering specifications
Cost certainty Indicative, subject to detail design Higher certainty
Typical issuance time ~60 working days 90-180 days for complex cases

From an investor perspective, an asset with STMG accepted but TICA not signed still carries cost and timeline risk. By contrast, an asset with TICA signed and paid has substantially crystallized its connection rights. Consequently, the practical bankability threshold is TICA signature, not STMG acceptance.

Terna vs DSO: scope and responsibilities

The Italian grid operator landscape splits responsibilities between Terna (the national TSO) and the local DSO (Distribution System Operator). Therefore, the relevant interlocutor depends on the connection voltage level and on whether new infrastructure is required.

Terna scope (TSO — Transmission System Operator)

Terna manages the Italian transmission grid: high voltage (HV, >132 kV) lines and substations. Specifically, Terna handles connections of large utility-scale projects typically above 10 MWp that require direct HV interconnection. Furthermore, Terna is responsible for the underlying transmission infrastructure capacity, including reinforcement plans (PdS — Piano di Sviluppo).

DSO scope (Distribution System Operator)

The DSO manages medium voltage (MV, typically 15-20 kV) and low voltage distribution. In particular, e-Distribuzione is the largest DSO covering ~85% of the Italian territory; additionally, there are local DSOs such as Areti (Rome), Acea, Inrete (parts of Emilia-Romagna). The DSO handles connections of medium-size projects typically below 10 MWp via cabina primaria.

Hybrid scenarios

For projects in the 10-50 MWp range, the connection can be either MV via cabina primaria or HV via dedicated substation. As a result, the choice depends on local grid availability, distance to existing infrastructure, and economic considerations. Moreover, in some cases the project triggers a Terna upgrade even when the formal connection point is at MV level.

Typical connection costs by voltage level

Connection costs vary significantly by voltage level, distance to existing infrastructure, and the scope of works required. The following ranges are indicative for the Italian market in 2026:

Connection type Typical cost range Typical scope of works
MV via existing cabina primaria €100k-500k Standard MV connection, switchgear
MV with dedicated cabina primaria €500k-2M New cabina primaria, transformer
HV connection to existing substation €1M-5M Bay extension, HV line
HV with dedicated substation €3M-10M+ New substation, HV line, switchgear

📌 Cost ranges are indicative and vary by region, distance, and specific scope. In particular, the HV transformer alone can cost €1-3M with lead times of 40+ weeks. Consequently, this is often the critical path for new substations.

Grid bottlenecks in Italian zones: 2026 picture

Despite increasing investment in grid reinforcement, several Italian zones experience congestion that limits effective injection capacity. As a result, even projects with valid TICA may face curtailment risk. The most relevant constraints in 2026 are concentrated in the following zones:

  • 🚩 Apulia: high concentration of renewable generation (PV + wind) leading to local congestion in specific portions of the HV grid. Notably, Terna’s PdS includes major reinforcements but the timeline is multi-year.
  • 🚩 Sicily: limited interconnection capacity between Sicily and the mainland via the new Tyrrhenian Link (still in development). Therefore, internal grid management has stricter capacity constraints.
  • 🚩 Sardinia: similar limitations on interconnection. However, the Tyrrhenian Link will substantially improve the situation when commissioned.
  • 🚩 Basilicata, Calabria, Molise: emerging renewable concentration creating localized constraints, particularly during high-irradiation summer hours.
  • 🚩 Lazio, Abruzzo: generally less constrained, although specific sub-zones have HV bottlenecks.
  • ✅ Northern regions (Lombardy, Piedmont, Veneto, Emilia-Romagna): typically less congested, although grid capacity is being increasingly allocated. By comparison, irradiation is lower than the South.

Macse mechanism: BESS as grid solution

In response to growing grid congestion and increasing PV/wind penetration, Terna has launched the Macse (Mercato della Capacità di Stoccaggio Elettrico) mechanism. Specifically, Macse incentivizes battery storage systems to provide grid services and time-shift renewable production. As a result, BESS co-location is becoming increasingly relevant for new PV projects, especially in congested zones.

For investors, co-located BESS can improve project bankability by reducing curtailment risk and capture rate erosion. Furthermore, BESS revenue from Macse can complement the PPA/merchant revenue from PV. However, the BESS-PV integration requires technical and contractual coordination that adds complexity to construction setup.

How our advisory supports grid connection due diligence

For investors evaluating grid-approved Italian PV opportunities, our advisory typically covers:

  • 🔍 Pathway identification: confirmation of voltage level (HV/MV), operator (Terna/DSO), milestone status (STMG/STMD/TICA)
  • 📋 Document verification: STMG/STMD content review, TICA terms analysis, payment status, deadlines
  • ⏱️ Timeline realism check: cross-check of Terna/DSO works schedule with realistic construction planning
  • 📊 Grid zone analysis: assessment of broader zone constraints and curtailment risk based on public Terna data
  • 🔋 BESS co-location feasibility: preliminary assessment of Macse opportunity for the specific asset
  • 🤝 Technical advisor coordination: liaison with the investor’s technical advisor on grid matters during DD

We do not act as technical advisor of record on grid matters or as legal counsel on TICA disputes. Instead, those engagements remain with qualified Italian technical advisors and law firms commissioned by the investor.

Frequently asked questions

What is the difference between STMG and TICA?

STMG (Soluzione Tecnica Minima Generale) is the technical proposal issued by the grid operator (Terna or DSO) defining the connection point, voltage level and indicative costs. TICA (Testo Integrato Connessioni Attive) is, by contrast, the binding connection contract signed after STMG acceptance, which crystallizes connection rights, specific costs, payment schedule and deadlines. Bankability typically requires TICA signed and paid, not just STMG accepted.

Who manages grid connections in Italy: Terna or the DSO?

It depends on the voltage level. Specifically, Terna (national TSO) manages high voltage (HV) connections, typically for projects above 10 MWp requiring direct HV interconnection. By contrast, the local DSO (e-Distribuzione, Areti, Acea and others) manages medium voltage (MV) connections via cabina primaria for medium-size projects. Moreover, for projects in the 10-50 MWp range, either pathway may apply depending on local grid availability.

What are typical connection costs for utility-scale solar in Italy?

Indicative ranges in 2026: €100k-500k for MV connection via existing cabina primaria, €500k-2M for MV with dedicated new cabina primaria, €1M-5M for HV connection to existing substation, and €3M-10M+ for HV with dedicated new substation. Costs vary significantly by region, distance to existing infrastructure, and specific scope of works. In particular, the HV transformer alone can cost €1-3M.

Which Italian regions have the most grid congestion?

The most congested zones in 2026 are Apulia (high PV+wind concentration), Sicily and Sardinia (limited mainland interconnection), and parts of Basilicata, Calabria, Molise (emerging renewable concentration). By comparison, Northern regions (Lombardy, Piedmont, Veneto, Emilia-Romagna) are typically less congested, although they have lower irradiation. Terna’s Piano di Sviluppo (PdS) includes major reinforcements, but the timeline is multi-year.

What is the Macse mechanism and how does it affect PV investments?

Macse (Mercato della Capacità di Stoccaggio Elettrico) is a Terna mechanism that incentivizes battery storage systems to provide grid services and time-shift renewable production. As a result, BESS co-location is becoming increasingly relevant for new PV projects, especially in congested zones. Furthermore, BESS revenue from Macse can complement PPA or merchant revenue from PV, reducing curtailment risk and improving project bankability.

How long does grid connection typically take after TICA signing?

Typically, 12-24 months from TICA signature to grid readiness, depending on the scope of works required. Specifically, projects connecting to existing infrastructure (no new substation) are significantly faster, often 6-12 months. By contrast, projects requiring a new dedicated HV substation can take 18-24+ months due to HV transformer lead times (40+ weeks). Furthermore, the operator side works are frequently the critical path.

Related advisory pages

📞 Validate the grid connection status of your Italian PV opportunity

Before submitting an asset to IC, our pre-IC screening verifies milestone status (STMG/STMD/TICA), payment progression, Terna/DSO works schedule, and zone-level constraints. Available within 5-10 working days after NDA.

📞 For Italy-based callers: green number 800 955358 (Monday-Saturday, 8:00-19:00 CET)

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