Solar plus storage in Italy: designing for a storage-led grid

Italian solar projects now earn more when storage is designed in from day one. Midday curtailment, the risk of falling capture prices, and congested southern grids threaten solar-only revenue, while Terna's fixed-revenue storage auctions and 15-minute trading reward flexibility. Modeling the battery at feasibility avoids later substation redesigns and gives lenders a clearer revenue case.

Italy's storage market is growing quickly, and the grid around it is being rebuilt. Terna, Italy's transmission system operator (TSO), plans to invest over €23 billion in the national grid through its 2025 to 2034 development plan.

Enel brought five major battery energy storage system (BESS) projects online across Italy in 2025, adding close to 4 GWh of storage. The country's storage auction, the Meccanismo di approvvigionamento di capacità di stoccaggio elettrico (MACSE), awarded 10 GWh for 2028 delivery in its first round, with bids topping demand more than fourfold. A second round for 16 GWh is set for November 24, 2026, for 2029 delivery. Across three rounds, MACSE aims to support up to 50 GWh, so much of that capacity is still to be won.

Price volatility gives batteries more ways to earn, which favors developers who pair storage with credible revenue logic.

Why do Italian solar economics now favor storage-backed projects?

In solar-heavy markets, curtailment tends to erode midday revenue first, and Italy's high-irradiation south is starting to see the same pattern. Investors have responded by turning to hybrid projects as a hedge against that cannibalization. Our analysis of utility-scale storage in Italy covers the move toward hybrids in more detail.

Market rules now reward flexibility. The Testo integrato del dispacciamento elettrico (TIDE) reforms cut electricity trading intervals to 15 minutes, which gives batteries more chances to earn from short price swings. MACSE makes financing easier by giving lenders a contractually guaranteed revenue floor. It pays a fixed long-term fee per megawatt-hour of capacity rather than per megawatt of peak output, which favors long-duration BESS.

Storage can earn in more than one market. Developers can split capacity between grid-service contracts and open-market trading, backstopping a project with fixed payments while still capturing merchant volatility. Balancing is opening up too: Italy's energy regulator has approved Terna's work plan to join the Manually Activated Reserves Initiative (MARI), Europe's shared platform for manual frequency restoration reserves.

Designing storage in from the start

That buildout raises the value of solar plus storage projects in Italy that are designed around dispatch flexibility. A solar-only plant can still look bankable on paper if there is guarantee that Italian prices stay high. The risk is that if those prices fade, and a plant built without early storage modeling ends up generating more than it can profitably sell.

Are Italy's high solar prices a reliable long-term signal?

On the surface, the numbers are encouraging. Italy's solar capture price reached €125/MWh in March 2026, and its annual capture rate of around 86% leads Europe. The national wholesale price averaged about €116/MWh in 2025, according to the Gestore dei mercati energetici (GME), Italy's power market operator.

Those figures make a pure merchant strategy look attractive, but they rest on conditions that may not last. Italian power prices are still propped up by gas, and that support could weaken as gas-power decoupling hands more price-setting hours to renewables. Early signs are already visible. In one record month, prices cleared below €1/MWh for a combined 19 hours, mostly on weekends and holidays, when industrial demand fell away but solar output stayed high.

How do grid bottlenecks affect southern Italian solar?

Congestion has long been a problem in southern Italy and Sicily, and it is set to intensify as solar buildout outpaces transmission. The lines running north can't yet carry the surplus to where demand is concentrated. Terna's development plan aims to raise exchange capacity between market zones from about 16 GW to about 39 GW, which gives a sense of the gap. Our piece on adapting Italy's grid looks at the upgrades underway.

Until that capacity arrives, curtailment is likely to climb. Montel News reports that it could rise sixfold by 2030 from the 338 GWh curtailed in 2024. Italy's national energy and climate plan, the Piano nazionale integrato per l'energia e il clima (PNIEC), targets 79.2 GW of solar by 2030. As the fleet grows toward that figure, mandatory export limits and sub-one-euro hours could become more common.

The risks of planning to retrofit

In these congested zones, a solar-only plant with a loose plan to add storage later carries two risks. It may face very low midday prices from its first year of operation, and it may need a substation redesign when the battery finally arrives.

Permitting adds time on top. Italy's Autorizzazione Unica can be slow. A 25 MW battery in Buja, authorized in late 2025, had been in approvals since mid-2023. The much larger 486 MW Fiscaglia project spent more than a year waiting for sign off. Approval times vary by region, as we explored in our look at regional approvals in Italy.

Reforms may not speed up the next wave of storage projects. As of the start of this year, over 70% of renewable and storage projects submitted for environmental review were reportedly still stuck in the administrative pipeline.

Grid connection is a growing schedule risk for Italian projects. Our eBook, How to navigate Italy's TSO connection delays, explains the north-south transmission constraints behind the queue and shows how to design around export limits and curtailment risk from the first submission. Download the guide.

Can you add storage to an existing Italian solar plant?

Yes, and for many operating plants it is a sensible next step. Co-locating a BESS at an existing site can recover curtailed output and open new revenue streams. It works best when the original design left spare land and substation headroom for it. Where the grid connection needs changing, expect new grid studies and possibly extra authorization steps. That is why new-build projects benefit from modeling storage at feasibility. For operating assets, our guide to repowering solar plants in Italy covers the options.

What should developers model before adding storage?

Adding storage later restarts the clock on engineering studies and grid reviews, and the market conditions you planned around may have changed by the time a retrofit is approved. Modeling the battery early is the defensive move. It tells you:

•       How much extra solar capacity is worth building.

•       How much midday output the battery can save.

•       Whether a longer-duration battery earns enough to justify its cost.

For a step-by-step method, see our guide to BESS sizing in Italy.

The answers matter for financing as much as for yield. A battery gives your model something solar alone can't: control over when the power earns.

Frequently asked questions

What is MACSE?

MACSE is Italy's centralized storage procurement mechanism, run by Terna. Winning projects sign 15-year contracts that pay a fixed annual fee per megawatt-hour of capacity, which gives lenders a predictable revenue floor.

How does TIDE affect battery revenue in Italy?

TIDE is Italy's revised dispatching code, and one of its main changes moves trading to 15-minute intervals. Shorter intervals mean more frequent price swings, and each swing is a chance for a battery to earn through trading or balancing.

Should an Italian hybrid project use AC-coupled or DC-coupled storage?

It depends on the site. Direct current (DC) coupling shares the solar inverters and can store energy that would otherwise be clipped, which suits new-build hybrids in high-curtailment zones. Alternating current (AC) coupling is usually easier to add to an existing plant. Comparing both at feasibility shows which returns more.

Why is curtailment higher in southern Italy?

Southern regions and the islands have the strongest irradiation but limited transmission to the north, where most demand sits. When local output exceeds what the grid can export, plants are curtailed or sell into very low prices. A battery can absorb that surplus and discharge it later.

Building storage-led projects in RatedPower

RatedPower lets you test a solar plus storage design for Italian sites from the feasibility stage:

•       Compare AC-coupled and DC-coupled BESS configurations.

•       Design standalone BESS projects.

•       Define and test storage capacity.

•       Place containers or racks within the site layout, using pre-defined BESS layouts.

You can then generate engineering documents directly from the design, including:

•       BESS layouts.

•       Bill of materials (BoM).

•       Design reports.

•       Drawings

•       3D shading scene exports for energy yield studies.

That gives you documentation for internal review and the technical detail lenders and offtakers ask for.

Want to see how a storage-led design performs on your site? Request a demo and we will walk you through a hybrid solar and BESS layout, from feasibility layout to design documentation.