Standalone and co-located batteries earn from more than one source. Understanding which revenues stack — and, more importantly, which a lender will actually credit — is what separates a financeable project from an optimistic spreadsheet. In Romania, the gap between the two is currently wide.
The revenue layers
A Romanian battery can, in principle, address several markets at once. It can sell balancing energy and ancillary services — frequency response and reserves — procured by the transmission system operator, Transelectrica. It can arbitrage the day-ahead and intraday energy markets operated by OPCOM, charging when prices are low and discharging when they are high. And, co-located behind a PV plant, it can shift solar output into higher-price evening hours. The relative weight of each layer shifts with market conditions; the discipline is to model the stack conservatively, not to assume the most aggressive layer persists for fifteen years.
| Revenue layer | Counterparty / market | Character | Lender treatment |
|---|---|---|---|
| Balancing & ancillary services (frequency, reserves) | Transelectrica | Regulated / procured | Partly creditable |
| Energy arbitrage (day-ahead / intraday) | OPCOM markets | Merchant, volatile | Discounted |
| Co-location with CfD-anchored PV | State CfD (15 yr) | Contracted | Underwritten |
| Capacity / contracted tolling (where available) | Offtaker / scheme | Contracted | Underwritten |
What banks actually underwrite
Here is the distinction that decides the debt sizing. Lenders discount volatile merchant revenue heavily and credit contracted or regulated cash flows far more generously. A revenue stack that looks rich on a merchant-arbitrage basis can support surprisingly little senior debt, because the bank sizes its loan against the cash flows it believes will be there in a bad year — not the central case.
The financeable battery is not the one with the highest modelled revenue. It is the one with the most contracted revenue. Arbitrage upside is for equity; debt is sized on what is underwritten.
This is why co-location with a CfD-anchored PV asset, or a contracted ancillary-service position, strengthens the debt case so materially relative to pure merchant arbitrage. The CfD brings a fifteen-year contracted floor into the same project; the battery's merchant arbitrage then becomes equity upside layered on top of a bankable base, rather than the foundation the whole financing depends on.
The policy tailwind
Romania is actively subsidising the capex side of this equation. A dedicated battery-storage support scheme of roughly €150 million from the Modernisation Fund — covering both standalone and behind-the-meter systems — was set in motion for late 2025, following an earlier €103 million storage grant scheme cleared in 2023. Grant support lowers the capex base, which improves the debt-service coverage on whatever revenue stack the project can contract. It does not, by itself, make merchant arbitrage bankable — but it widens the margin for the projects that pair storage with a contracted revenue line.
What this means
For an investor, the Romanian BESS opportunity is real but structurally specific. The projects that finance cleanly are not the merchant-arbitrage plays that dominate investor decks; they are the ones that anchor the battery to something contracted — a co-located CfD PV plant, a procured ancillary position, or a grant-reduced capex base — and treat the volatile arbitrage layer as equity upside, not debt collateral. Knowing which revenues stack is table stakes. Knowing which ones a Romanian credit committee will actually fund is the edge.
Sources: ANRE; Transelectrica (balancing and ancillary services); OPCOM (day-ahead and intraday market documentation); European Commission / Romanian Ministry of Energy, Modernisation Fund battery-storage support scheme (~€150m, 2025) and 2023 electricity-storage State Aid scheme (~€103m). Capex and revenue characterisations are indicative.
This note is general market commentary, not investment advice. Revenue layers and their financeability are indicative and depend on market conditions, contract structure and lender appetite; no return is promised or guaranteed. SolarPlants is the commercial brand of VERDEVOLT PROIECT S.R.L.