A 3 MWh battery container on a ten-year lease. €500K in, up to 20% gross per year.

Your EU company buys a 3 MWh lithium-ion battery container for €500,000. The same company leases the container to a licensed Romanian grid operator on a ten-year fixed-rent contract. Up to 20% gross per year (EUR, ~€100K on a single container) lands quarterly on your company bank account. At year ten, you renew the lease at a reduced rate reflecting cell degradation, re-lease to a different operator, or sell the container on the secondary market.

Three things make this structurally different from most energy investments.

First, the rent is fixed and contractual. Not a forecast. The lease specifies the quarterly payment for the full ten years. The grid operator captures the Romanian day-night price spread, takes the spread risk, and pays you a fixed rent regardless of how that spread moves.

Second, the asset is yours. The container sits on your EU company's balance sheet from delivery onward. You hold a physical, insured, warranted piece of equipment with a defined market value. 10-year equipment depreciation typically provides a useful tax shield against the rental income.

Third, the operating risk is one layer removed. Your job is to own the asset and collect rent. The operator's job is to make the asset productive and pay the rent. Day-night arbitrage, grid-services contracts, dispatch optimisation, regulatory licensing, all of that is the operator's concern, not yours.

Standard equipment leasing applied to a battery. Same legal pattern leasing companies have used for fifty years for trucks, generators, factory equipment.

The asset

A 3 MWh lithium-ion battery container in a 40-foot industrial form factor, configured for 4-hour discharge (typical day-night arbitrage profile). Hardware cost approximately €150,000 per MWh installed at current 2026 prices. Manufactured by a Romanian battery manufacturer in Brașov on the same production line as the two operating 250 kW units already deployed in the same industrial park. Tier-1 EU insurance (Allianz or Generali class carriers) provides full-replacement cover for the lease duration. 10 to 15-year manufacturer warranty on the cells.

The vehicle

Your EU-domiciled company is the buyer of record. For VAT efficiency, the company is typically domiciled outside Romania so the intra-EU acquisition is handled under reverse charge (zero VAT cash impact at purchase). If you already have an EU company in a treaty-friendly jurisdiction (Austrian GmbH, Dutch BV, Cypriot Ltd, Luxembourg SARL), it can be the buyer. If not, the structuring covers formation of a fresh vehicle in the right jurisdiction.

The lease

A standard EU equipment lease between your company (lessor) and a licensed Romanian grid operator (lessee). Fixed quarterly rent. Ten-year term with renewal optionality at year ten. Operator covers all site costs (grid connection, substation interface, maintenance, dispatch, regulatory licensing). Your company collects rent, holds the asset, pays the local accountant.

Insurance is structured as a standard equipment-lease covenant: the operator is contractually required to keep the container insured under the tier-1 policy for full replacement value throughout the lease, with your EU company named as loss payee. The premium is paid by the operator as part of their site operating cost, not invoiced back to you.

Single-container entry economics. The cascade below assumes profits are distributed each year (worst tax case); reinvesting into a second container defers the dividend WHT and compounds at the company-level net.

The 20% headline is the contractual gross rent on the lease, before any company overhead or tax. The numbers above walk the cascade so there are no surprises in year one. Three variables shape where in the net range you land.

EU company jurisdiction. A Romanian SRL keeps overhead low (~€2K-€3K/yr) and CIT at 16%. Other EU jurisdictions trade off: Hungary lower CIT but higher accounting cost, Austria higher CIT but stronger institutional credibility. At the €500K ticket size the per-deal overhead is small as a percentage either way.

Dividend distribution strategy. Tax only crystallises when profit distributes to you personally. If the rent is rotated into a second container rather than distributed, you defer the dividend WHT and compound the position at the company-level net yield. For a multi-container position scaling toward €5M, this is the standard pattern.

Calendar Year 1 lag. A 3 MWh container is more involved to deploy than a mobile trailer: manufacturing, transport, site preparation, grid connection, commissioning. Budget 6 to 9 months from wire to first quarterly rent. Calendar Year 1 effective gross yield lands closer to 5 to 12% depending on commissioning date. From Year 2 onward, four full quarterly payments per calendar year produce the headline 20%.

The deal scales linearly by acquiring additional containers on the same lease structure. The per-container economics are identical; the marginal company overhead is near zero. Larger commitments typically negotiate preferred terms on the unit price and the lease conditions.

On a €500K single-container entry across the full ten-year lease, cumulative gross rent is approximately €1,000,000 against the original €500K capital. Cumulative gross at scale on €5M would land around €10M+. Net of company overhead, corporate tax, and dividend withholding, the in-pocket cumulative is roughly 70-75% of these gross figures depending on jurisdiction and distribution strategy.

Returns are pre-tax in the table above; effective rate depends on jurisdiction. BESS amortisation under 10-year equipment depreciation typically provides a tax shield that reduces the effective CIT burden in years 1-10.

The 20% gross yield on a fixed lease is specifically Romanian. The same container in Germany would lease at 5 to 8% gross. The difference comes from three structural factors that together make Romanian battery storage the highest-yielding regulated grid asset in the EU.

The day-night spread is the widest in the EU. Romanian power prices swing 15 to 25% between day and night. The driver is accelerating residential and commercial solar installation pushing daytime supply up against limited storage capacity to absorb it. The grid operator captures that spread through arbitrage and grid-services contracts. The fixed rent paid to the investor is funded by that spread. In Germany the spread is closer to 5 to 8% and the same arbitrage produces operator economics that cannot support 20% lease rents.

EU funding accelerates the build-out. The Romanian government has earmarked €300M specifically for standalone battery energy storage systems under the EU recovery framework. The subsidy goes to operators, not to investors directly, but it lowers the operator's cost of capital and allows them to commit to fixed rents over ten-year horizons that would otherwise be unaffordable.

The pipeline is committed, not announced. Listed Romanian utilities have 2 GW+ of battery storage in their build pipeline through 2030. That pipeline sustains operator demand for new units at current rent rates and creates an active secondary market for containers at year ten when the original lease matures.

The combination is specifically Romanian. The deal exists where the economics allow it, not where the brand recognition would be more comfortable.

For a fuller treatment of the Romanian BESS landscape across all three private-investor structures (mobile trailer, stationary container, project equity), read the BESS investment pillar.

Honest framing. A ten-year horizon means you should plan for at least one of these to test the structure.

1. Operator counterparty failure during the lease. The fixed rent is contractual but only as good as the operator paying it. Mid-term operator default is the largest single risk on a ten-year lease. The mitigant is physical asset retention: your EU company owns the container, the lease specifies recovery rights, and a stationary container at a known grid site can be re-leased to a different operator on the same site or transported to another. The recovery is more involved than for a mobile trailer (see section 08), but the asset is yours throughout.

2. Day-night spread compression. The 15 to 25% spread funds the operator's economics. As more battery storage is built into the Romanian grid through 2030 the spread will likely compress. The fixed-rent contract insulates the investor from spread compression during the lease term. The risk shows up at year ten in renewal pricing: a compressed spread means lower rents on subsequent contracts.

3. Subsidy and regulatory shifts. The €300M Romanian support scheme drives the build-out pace. A change in subsidy terms changes operator economics and, over time, lease renewal rates. EU-wide regulatory shifts on grid services (capacity payments, frequency reserve markets) can also affect operator revenue mix without affecting your fixed rent during the lease term but with material impact at renewal.

4. Residual value at year ten. Lithium-ion cell capacity at end of warranty is typically 70 to 80% of original. The container is still operational but produces less revenue, and the secondary market price reflects that. Cumulative rent during the original lease (~€1M against €500K entry on a single container) covers principal with margin, so residual is upside, not downside, but the upside is meaningfully smaller than year-one asset value.

5. FX and tax-residency considerations. Rent is denominated in EUR. For USD, GBP, or other base currencies, quarterly distributions translate at the prevailing rate. A 5 to 10% EUR weakening across the lease compresses returns measurably. FX hedging is available for sustained positions and adds 0.5 to 1.5% per year in cost. Tax residency of the holding company shapes the dividend WHT and the available treaty relief.

The original ten-year lease ends at year 10. Three realistic paths beyond, all at a lower economic level than years 1-10 because cell capacity has degraded to 70 to 80% of original. None of them continue at the original 20% headline rate.

1. Renew with the same operator at a reduced rent reflecting cell degradation. Typically 60 to 70% of original rate, which is roughly 12 to 14% gross on the original €500K ticket. Real income, but below the original lease rate. Plan for this in your model rather than assuming 20% continues.
2. Re-lease to a different operator through the standard recovery mechanism (site change requires container transport plus new grid connection at the destination). Fresh lease at a renegotiated rate, typically in the same 12 to 14% gross range given the same underlying cell degradation.
3. Secondary sale of the container to a new owner-operator at approximately 30 to 50% of original price (€150K to €250K on a €500K original ticket). Realises residual rather than continuing income, useful if you want to redeploy the capital elsewhere.

The math works out: cumulative gross rent across the original ten-year lease (~€1M) already exceeds the €500K entry capital by year five. Everything from year five onward is positive carry. The year-10 paths are upside relative to the principal, not the case for the deal.

The case for the deal is the contractual ten-year rent stream at 20% gross. The case beyond year 10 is whatever the Romanian BESS market looks like in 2036, which neither of us can fully forecast today.

The mobile BESS trailer and the stationary BESS container are the same lease economics applied to different form factors. The choice is about ticket size and downside design.

The stationary container is the right deal for an allocator with €500K+ who wants the higher 20% gross yield and is comfortable owning a single asset on a single site for ten years. The mobile trailer is the right deal for an allocator with a smaller ticket (€80K) or who values the relocation optionality of a road-legal asset.

Both deals are sourced from the same manufacturer (Romanian battery manufacturer in Brașov), structured through the same EU company pattern, and leased to operators in the same regulatory class. The asset choice is the deal choice.

For the full mobile BESS walkthrough, read the mobile BESS guide. For comparison across all five live deals at your specific ticket and horizon, the calculator filters the live shelf and shows which deals fit.

Stationary containers take longer to deploy than mobile trailers because of the site preparation and grid connection. The sequence:

1. Thirty-minute investment call. I walk you through the container specification, the lease contract, the operator counterparty, the scaling table for larger commitments. Fit for your ticket size, your jurisdiction, and your tax residency.
2. Brașov site visit and data room. Inspect the two operational 250 kW units in the same industrial park, the manufacturer facility, and the grid connection setup. Lease draft, manufacturer documentation, insurance terms, operator references. Typically arranged within 2 to 3 weeks of the first call.
3. EU company setup if needed. If you already have an EU company in a treaty-friendly jurisdiction, skip this step. If not, the operator handles formation in 1 to 3 weeks depending on jurisdiction.
4. Container order and capital wire. €500,000 wired from your EU company to the manufacturer. Container enters the production queue.
5. Manufacturing, transport, site prep, grid connection (4 to 6 months). Container manufactured, transported to site, installed in the industrial park slot, connected to the grid, commissioned. Operator-managed; investor receives updates at each milestone.
6. Lease commencement and first quarterly rent (~90 days after commissioning). Lease starts on commissioning. First payment lands on your EU company bank account three months later. Quarterly pattern continues for ten years.

Total elapsed time from first call to first rent payment is typically 6 to 9 months. After the first cycle, subsequent quarterly payments continue automatically per the lease schedule. Adding additional containers later runs faster (the EU company is already set up, the manufacturer slot is queued).