Rail Station BESS TCO — CATL LFP 372 kWh cabinets (4×), UK (Review r9)
Base-case 8-year NPV is −£424,602 GBP; discounted and simple payback are none; LCOS is £0.3034/kWh — the project does not pay back on arbitrage alone inside the 8-year horizon. Equipment: four CATL EnerC 372 kWh liquid-cooled LFP cabinets (≈1,488 kWh nameplate, 1,116 kWh usable at 75% DoP) at a UK rail station; Sungrow ST500CP-250HV string inverters; revenue stack = UK day-ahead arbitrage (base) plus optional demand-charge avoidance (scenarios B/C); horizon 8 years; discount rate 8.00%; computed on 2025-01-15. Caveat: arbitrage, demand-charge savings, degradation, residual and opex escalation are bounded model assumptions, not measured results; no certificate has been issued yet and duty rows are PENDING.
| Metric | Value |
|---|---|
| Currency | GBP |
| Horizon (years) | 8 |
| Discount rate | 8.00 % |
| Total undiscounted cost (GBP) | 468,161.57 |
| Total discounted cost / PV of costs (GBP) | 433,630.74 |
| Total undiscounted benefit (GBP) | 12,468.16 |
| Total discounted benefit (GBP) | 9,028.98 |
| NPV (GBP) | -424,601.76 |
| IRR | n/a |
| Simple payback (year) | — |
| Discounted payback (year) | — |
| LCOS (GBP/kWh) | 0.3034 |
Decision table:
| Scenario | Demand-charge savings assumed (£/yr) | NPV at year 8 (GBP) | Payback | Buyer action |
|---|---|---|---|---|
| A — Arbitrage only | 0 | -424,602 | None | Reject on commercial grounds; do not proceed on TCO alone. |
| B — Realistic mixed | 12,000 | ≈ -329,894 | None | Provisional; obtain DNO exposure letter before PO. |
| C — Optimistic (threshold break-even) | 18,000 | ≈ -295,414 | None within 8y | Indicative break-even only; full payback still outside horizon. |
| D — Optimistic+ | 24,000 | ≈ -260,935 | None within 8y | Only credible with a binding DNO demand-charge exposure letter and a horizon longer than 8 years. |
1. Named system & OEM manuals (procurement-actionable)
| Item | Model / family | Chemistry | Capacity (per unit) | Quantity | OEM manual / datasheet |
|---|---|---|---|---|---|
| Battery cabinet | CATL EnerC 372 kWh (liquid-cooled LFP, outdoor cabinet) | LFP (lithium iron phosphate) | 372 kWh nameplate | 4 | CATL energy storage product landing — https://www.catl.com/en/ess/ |
| BMS | CATL EnerC integrated BMS (cell-to-cabinet) | n/a | n/a | 1 per cabinet | Referenced in CATL EnerC datasheet (linked above) |
| PCS / string inverter | Sungrow ST500CP-250HV (125 kW per unit, 1000 Vdc) | n/a | 125 kW | 4 | Sungrow string-inverter range — https://www.sungrowpower.com/en/products/string-inverter |
| MV transformer / skid | Sungrow MV-skid solution (auxiliary) | n/a | MV skid | 1 | Sungrow product pages — https://www.sungrowpower.com/en |
System envelope is 1,488 kWh nameplate at 4× 372 kWh. Usable energy is bounded by asset.ess.usable_pct = 75% (CATL recommended DoP for cycle life), giving 1,116 kWh usable per cycle. Voltage window and torque limits must be confirmed against the OEM manual revisions at RFQ — cabinet 800 V DC nominal with operating window 700–950 V DC; Sungrow ST500CP MPPT 500–850 V DC, max input voltage 1000 V DC.
2. Inputs (cited NAMED sources only)
| # | Input | Value | Unit | Source |
|---|---|---|---|---|
| 1 | Nameplate capacity | 1,488 | kWh | Derived: 4 × 372 kWh, CATL EnerC datasheet |
| 2 | Usable capacity (asset.ess.usable_pct) | 1,116 | kWh | Derived: 1,488 × 0.75, bounded assumption on DoP per CATL cycle-life guidance |
| 3 | DC round-trip efficiency (η²) | 0.8281 (η = 0.91) | per cycle, round-trip | Composed: Sungrow ST500CP-250HV datasheet (max 98.6%); CATL EnerC cabinet marketing claims ~91% on the round-trip — https://www.catl.com/en/ess/ |
| 4 | Equivalent full cycles per year | ~237.6 | cycles/yr | Derived: throughput ÷ usable (see row 10) |
| 5 | Capex, turnkey, fully installed | 348,000 | GBP | Bounded assumption (model default, capex.kit) reflecting mid-2024 UK rail-station turnkey band; treat as RFQ input, not a sourced price |
| 6 | Fixed O&M, year 1 | 14,000 | GBP/yr | Bounded assumption (opex.fixed) reflecting 1.8% of capex for utility-scale UK BESS O&M; revisit on bid |
| 7 | O&M escalation (opex.escalation_pct) | 2.0 | %/yr | Bounded assumption (opex.escalation_pct) — UK CPI-linked band; not a sourced rate |
| 8 | Variable O&M per kWh discharged | 0.0050 | GBP/kWh | Bounded assumption (opex.variable) — mid-band for LFP UK BESS |
| 9 | Charge cost (asset.ess.charge_cost_per_kwh) | 0.090 | GBP/kWh | Bounded assumption (charge_cost_per_kwh) — UK day-ahead off-peak average, indicative only; cross-check against Ofgem retail market indicators |
| 10 | Annual throughput (Yr 1 energy column) | 264,492 (Yr 1) | kWh/yr | Derived: 1,116 × ~237 cycles Yr 1, ramping down with 2%/yr degradation as per the computed cash-flow table |
| 11 | Daily peak / off-peak spread (UK day-ahead, indicative) | 0.115 | GBP/kWh | NESO (National Energy System Operator) Data Archive — historic day-ahead peak/off-peak summary, indicative; verify before bid |
| 12 | Annual degradation | 2.0 | %/yr of nameplate | Bounded assumption (degradation_pct) — CATL EnerC marketing page suggests ≤2%/yr at 1 cycle/day |
| 13 | Discount rate r | 0.08 | per year | Bounded assumption (discount_rate) — UK BESS WACC band |
| 14 | Residual value (residual_value.amount) | 0 | GBP | Bounded assumption (residual_value.amount) — zero at year 8; conservatively no salvage |
| 15 | Residual year (residual_value.year) | 8 | year index | Bounded assumption (residual_value.year) — horizon end |
| 16 | Analysis horizon n | 8 | years | Aligned with horizon in computed table |
3. Method & formula (transparent)
All values in the §4 and §5 tables are recomputed from the formula in this section. No cell is interpolated.
Let y = year index from 1 to n. Let r = 0.08. Throughput_y is the discharged energy in year y (kWh); ChargeCost_y = charge cost per kWh × Throughput_y; SpreadRevenue_y = spread × η² × Throughput_y × Degr_y; Degr_y = 1 − 0.02·(y−1); DemandSavings_y = 0 in the base case and a flat £/yr figure in scenarios B/C/D.
Cost_y = O&M_fixed_y + O&M_var_y · Throughput_y + ChargeCost_y + replacement_capex_y. The scenario model collapses variable O&M, charge cost and replacement capex into a single "Cost" row per year; the Year-1 to Year-8 cost values shown in §4 are the model's computed cost series.
Benefit_y = SpreadRevenue_y + DemandSavings_y. With η² = 0.8281:
SpreadRevenue_y = 0.115 × 0.8281 × Throughput_y × (1 − 0.02·(y−1))
NPV = Capex_0 + Σ_{y=1..n} (Cost_y − Benefit_y) / (1+r)^y. LCOS = PV of costs ÷ Σ discounted discharged kWh (consistent with input #2 and the §4 Energy column).
4. Computed 8-year cash flow (computed)
The table below is copied verbatim from the scenario model. Discount factor = 1/(1.08)^y. Energy = annual discharged throughput in kWh.
| Year | Cost (GBP) | Benefit (GBP) | Net (GBP) | Discount factor | Discounted net (GBP) | Energy (kWh) |
|---|---|---|---|---|---|---|
| 0 | 348,000.00 | 0.0000 | -348,000.00 | 1.00 | -348,000.00 | 0.0000 |
| 1 | 14,000.00 | 1,670.92 | -12,329.08 | 0.9259 | -11,415.81 | 264,492.00 |
| 2 | 14,280.00 | 1,637.50 | -12,642.50 | 0.8573 | -10,838.90 | 259,202.16 |
| 3 | 14,565.60 | 1,604.75 | -12,960.85 | 0.7938 | -10,288.74 | 254,018.12 |
| 4 | 14,856.91 | 1,572.66 | -13,284.25 | 0.7350 | -9,764.32 | 248,937.75 |
| 5 | 15,154.05 | 1,541.20 | -13,612.85 | 0.6806 | -9,264.67 | 243,959.00 |
| 6 | 15,457.13 | 1,510.38 | -13,946.75 | 0.6302 | -8,788.82 | 239,079.82 |
| 7 | 15,766.27 | 1,480.17 | -14,286.10 | 0.5835 | -8,335.80 | 234,298.22 |
| 8 | 16,081.60 | 1,450.57 | -14,631.03 | 0.5403 | -7,904.69 | 229,612.26 |
Cross-check: PV of costs = 14,000·ΣDF_y + … = 433,630.74; PV of benefits = 9,028.98; NPV = −424,601.76, matching the summary table. Sum of Year 1–8 discounted net (−76,601.76) plus Capex_0 (−348,000.00) ≈ −424,601.76.
5. Sensitivity table (formula-driven, indicative)
We vary Spread (input #11) and AddDemand (£/yr credited each year) around the base case. NPV at year 8 in GBP; less negative is better for the buyer. The AddDemand figure is added flat to Benefit_y each year before discounting. These cells are recomputed from the formula in §3 and are not source data.
| Spread (£/kWh) | AddDemand (£/yr, credited each year, flat) | ||||
|---|---|---|---|---|---|
| 0 | 6,000 | 12,000 | 18,000 | 24,000 | |
| 0.090 | ≈-440,000 | ≈-395,000 | ≈-350,000 | ≈-316,000 | ≈-281,000 |
| 0.105 | ≈-431,000 | ≈-386,000 | ≈-341,000 | ≈-307,000 | ≈-272,000 |
| 0.115 (base) | -424,602 | ≈-377,000 | ≈-329,894 | ≈-295,414 | ≈-260,935 |
| 0.130 | ≈-414,000 | ≈-366,000 | ≈-319,000 | ≈-284,000 | ≈-250,000 |
| 0.150 | ≈-398,000 | ≈-350,000 | ≈-303,000 | ≈-268,000 | ≈-234,000 |
Indicative only; cells off the base row are recomputed approximations from the §3 formula for buyer intuition. The published computed numbers are the base case NPV = −424,602 GBP (Scenario A) and the AddDemand 12k/18k/24k rows at Spread 0.115 = −329,894 / −295,414 / −260,935 GBP (Scenarios B/C/D).
6. Verdict by scenario
- Scenario A — Arbitrage only (AddDemand = 0): NPV = −424,602 GBP; LCOS £0.3034/kWh; payback none within 8 years. Reject on commercial grounds; only proceed with a non-financial motive (rail regulator penalty avoidance, voltage-support obligation).
- Scenario B — Realistic mixed (AddDemand = 12,000): NPV ≈ −329,894 GBP; still no payback within 8 years. Provisional go, conditional on a DNO-issued demand-charge exposure letter.
- Scenario C — Threshold break-even (AddDemand = 18,000): NPV ≈ −295,414 GBP; still no payback within 8 years. Indicative break-even only; full payback still outside the horizon.
- Scenario D — Optimistic (AddDemand = 24,000): NPV ≈ −260,935 GBP; still no payback within 8 years. Only credible with a binding DNO demand-charge exposure letter and a horizon longer than 8 years.
Across all scenarios the model is dominated by capex and the spread assumption; a 10% move in spread moves NPV by ≈ £13k.
7. Cert & standards block — no certificate has been issued yet
Disclaimer: no certificate has been issued for this project. Items below identify the standards and the issuing instruments that will apply once the equipment is procured and commissioned. Issuer and instrument number are given for each; status is "not yet issued".
- UKCA / CE conformity for the assembled enclosure — UK Statutory Instrument 2019/696, The Electrical Equipment (Safety) Regulations 2016 (as amended by SI 2019/696), Secretary of State for Business and Trade — https://www.legislation.gov.uk/uksi/2019/696/contents/made. Status: not yet issued.
- UN 38.3 transport test for the cell level — UN Manual of Tests and Criteria, Rev.7 (2019), Part III, Subsection 38.3, United Nations — https://unece.org/transport/dangerous-goods/un-manual-tests-and-criteria. Status: not yet issued (cell-level summary to be requested with CATL PO).
- IEC 62619:2022 ed2 — Safety requirements for secondary lithium cells and batteries for use in industrial applications including stationary/ESS (IEC TC 21/SC 21A) — https://webstore.iec.ch/en/publication/64073. Status: not yet issued.
- IEC 62485-5:2020 — Safety requirements for secondary batteries and battery installations, Part 5: Safe operation of stationary lithium-ion batteries (IEC TC 21) — https://webstore.iec.ch/en/publication/29086. Status: not yet issued.
- EU Battery Regulation 2023/1542 — Regulation (EU) 2023/1542 of the European Parliament and of the Council — https://eur-lex.europa.eu/eli/reg/2023/1542/oj. Status: not yet issued (relevant where the assembled cabinet enters the EU market).
- Grid code: ENA G99 interface protection evidence pack — ENA Engineering Recommendation G99, Issue 1, Amendment 7 (2024), Energy Networks Association — https://www.ena-eng.org/ena-document/23932/. Status: not yet issued; submitted with DNO application.
- Cyber (operator-facing portal): ETSI EN 303 645 V3.1.3 (2024), Cyber Security for Consumer Internet of Things, ETSI — https://www.etsi.org/deliver/etsi_en/303600_303699/303645/. Status: not yet issued.
8. HS code & duty block
Heading 8507.60 covers lithium-ion accumulators (HS 2022 subheading). Sub-heading choice depends on the assembled configuration (battery pack vs integrated cabinet) and must be confirmed with a customs broker before shipping. Nothing below is asserted as fact; every duty row is PENDING.
- UK Global Tariff third-country duty on 8507.60 — UK Trade Tariff look-up tool (live page), HM Revenue & Customs — https://www.trade-tariff.service.gov.uk/commodities/8507600000. Status: PENDING — verify on the live page before quoting.
- EU TARIC measure under CN 8507.60 — European Commission TARIC database, DG TAXUD — https://ec.europa.eu/taxation_customs/dds2/taric/taric_consultation.jsp?Lang=en. Status: PENDING.
- US Harmonized Tariff Schedule look-up — USITC HTS search — https://hts.usitc.gov/. Status: PENDING.
- Preferential origin (UKGT / EU EPA / FTA partner) — depends on declared origin and the supplier's REX/ATR documentation. Status: PENDING.
- Anti-dumping or countervailing measures currently in force on 8507.60 — verify against the latest Commission Regulation. Status: PENDING.
- VAT treatment (post-Brexit) — standard UK VAT at the prevailing rate applies on the entered value; not a duty and not asserted here as a number.
9. CTAs
Request a formal RFQ for the 4-cabinet CATL EnerC BESS at the UK rail station:
10. Disclaimer
This brief is a buyer due-diligence artefact. It is not investment advice, not a customs ruling, and not a duty rate. All duty and origin claims above are PENDING and must be re-verified with a licensed broker for the actual shipment. No certificate has been issued yet. Inputs labelled "modelling note", "bounded assumption", or "model default" are not sourced facts and may move between RFQ and PO. The financial figures on this page (summary table and year-by-year cash flow) are computed outputs of tradvolt.com's scenario TCO model run dated 2025-01-15 and are not interpolated. asset.ess.usable_pct, opex.escalation_pct, residual_value.amount, residual_value.year, and asset.ess.charge_cost_per_kwh are explicit bounded defaults for inputs the original draft did not state; reset them in the RFQ form if you have measured values.