Rail-Station ESS 800 kWh EU — Use Case & TCO

Verdict (evidence date 2026-01-15): For an 800 kWh / 500 kW grid-tied stationary BESS at a mid-sized EU rail passenger station over a 15-year horizon at a 6.00% real discount rate, the scenario TCO model returns NPV = −634,384 EUR, PV of costs = 583,121.74 EUR, and LCOS = 0.2566 EUR/kWh. Simple payback = none and discounted payback = none within the 15-year horizon. Equipment family: CATL LFP 280 Ah prismatic cells in a Sungrow ST2752UX string PCS configuration. Limitation: this is a TCO envelope, not a tendered offer; customs duty rates are pending TARIC confirmation and benefit lines assume FCR admission.

1. Application and scope

Application: Grid-tied stationary battery energy storage system (BESS) deployed at a mid-sized EU rail passenger station, sized to support peak-shaving of traction substation feeders, ride-through for platform auxiliaries, and ancillary frequency regulation income where admitted by the relevant TSO.

Scope: TCO envelope only. Hardware and labor lines below are named to a specific public OEM product family. Customs duty rates in Section 7 are flagged PENDING because official TARIC confirmation is required at tender time.

Capacity basis: 800 kWh usable at the DC bus, 500 kW nominal AC power (≈1.6 h duration at nameplate), 1000 V DC battery string, 1 DC-coupled PCS skid with PV oversizing headroom. This is a nameplate reduction from the draft's prior 1.0 MW / 0.5 MW split: the scenario model uses 500 kW AC across the full revenue stack.

2. Named equipment and public sources

3. Model inputs (assumptions and bounded defaults)

4. scenario TCO summary (verbatim from model)

Reading the table: "Cost" is the cash outflow line (CAPEX in Year 0 plus OPEX each year). "Benefit" in this model is reported as a negative number because it is a credit against cost. The net NPV of −634,384.40 EUR therefore means: under the scenario, the 15-year discounted costs exceed the 15-year discounted benefits by roughly €634k — the project does not pay back inside the horizon on these inputs. LCOS = PV of costs / discounted lifetime energy throughput = 0.2566 EUR/kWh.

5. computed year-by-year cash flow (verbatim from model)

Notes on the cash flow:

• Year 0 is the upfront CAPEX line of 469,835 EUR. This reflects a sized equipment + EPC + soft-costs bundle for the named product family and is treated as a sunk cost at t = 0.
• "Cost" rises by ~2%/yr (OPEX inflation in the model's cost-side assumption).
• "Benefit" is negative in this model's sign convention (a credit). Its magnitude decays at the 2%/yr fade rate applied to throughput.
• Discount factors are 1.06^−t for t = 1..15.
• Cumulative discounted net over Years 1–15 ≈ −164,549 EUR; together with Year 0 (−469,835 EUR) this sums to the computed NPV of −634,384.40 EUR.
• Simple payback and discounted payback are both None because the annual net cash flow remains negative in every modelled year — the project does not cross zero.

6. Worked arithmetic (consistent with the computed table)

All figures in EUR unless stated. The previous draft mixed a 1 MW / 0.5 MW configuration with benefit lines tied to removed sources; this rewrite collapses the configuration to 500 kW AC and restates the worked math against the computed table.

Step A — Year-0 CAPEX.
The scenario model uses an upfront CAPEX of 469,835 EUR. This bundles: (a) CATL LFP 280 Ah cell-level hardware + BoS/enclosure sized to the 800 kWh DC bus; (b) Sungrow ST2752UX-class PCS at the 500 kW AC rating; (c) EPC, grid interconnection, and soft costs (permitting, studies). Equipment-specific pricing was not asserted as a sourced fact in this rewrite — the CAPEX value is the computed input to the cash-flow table.

Step B — Year-1 OPEX.
Year-1 cost line is 10,336 EUR, rising ~2%/yr to 13,638 EUR in Year 15. Treat this as a fixed-O&M envelope plus insurance and software/SaaS.

Step C — Throughput and benefit lines.
Year-1 energy throughput = 262,800 kWh. The Year-1 benefit line in the computed table is −5,927.85 EUR (a credit). This is a net figure: gross avoided-demand + load-shift credit, minus the charge cost paid for the energy stored (at asset.ess.charge_cost_per_kwh = 0.07 EUR/kWh assumption), minus an FCR-related credit line at the modelled TSO band. The benefit decays with the 2%/yr fade.

Step D — PV factors and discounting.
Discount factors at 6.00% real for t = 1..15 are 0.9434, 0.8900, 0.8396, 0.7921, 0.7473, 0.7050, 0.6651, 0.6274, 0.5919, 0.5584, 0.5268, 0.4970, 0.4688, 0.4423, 0.4173 (cumulative annuity factor ≈ 9.7122). These are the factors the computed cash flow uses and they match the values reported in the prior draft.

Step E — LCOS.
LCOS = PV of costs / lifetime discounted throughput = 583,121.74 / sum of (Energy × discount factor). Using the computed values, the model returns 0.2566 EUR/kWh.

7. Sensitivity envelope (illustrative, reuses the same computed cost lines)

Each row re-scales only the named variable and re-reads NPV against the computed cost / discount-factor schedule. The base computed NPV is −634,384 EUR. The previous draft's hand-rolled sensitivity (with three benefit scenarios) is replaced by a bounded ±10% / ±0.5 pp envelope on the single scenario, since the audit fixes one operating mode.

In all bounded sensitivities the NPV remains negative and neither simple nor discounted payback is achieved inside 15 years. The project is CAPEX-dominated; OPEX and fade move the headline NPV by single-digit %.

8. Verdict

Base scenario: NPV = −634,384.40 EUR over 15 years; LCOS = 0.2566 EUR/kWh; simple payback = None; discounted payback = None. On these inputs the rail-station ESS does not recover CAPEX inside the 15-year horizon.

Non-financial considerations: the use case maps cleanly to a 0.5–1.6 h discharge duration, aligns with substation peak events, and offers social value (ride-through for safety-critical platform loads, regulated-rail EMC compliance via EN 50121-4) that is not monetised in the numbers above. Under EU Battery Regulation 2023/1542, due-diligence and recycled-content documentation apply to the cell-level procurement.

Recommendation: issue a binding RFQ against the named product family (CATL 280 Ah LFP + Sungrow ST2752UX class PCS) to firm up Year-0 CAPEX and to obtain a definitive TSO admission position on FCR pre-qualification. Re-run this audit once a binding EPC cap and an actual charge-cost tariff are in hand; do not pursue on a stand-alone peak-only basis at this scale without a stacked-revenue path.

9. Certification and compliance to plan for

10. Customs — HS / TARIC block (duty rates PENDING)

11. CTA

This page is a TCO envelope, not investment, legal, or engineering advice. All numbers are illustrative engineering estimates and must be validated against a final issued offer. Equipment references are to publicly marketed OEM products cited via their public product pages; pricing was not asserted as a sourced fact and the Year-0 CAPEX is the computed input. Customs duty rates are explicitly PENDING. Decision-makers should re-run the audit with a binding EPC cap and a confirmed TSO admission position on FCR.