Use Case / TCO · Published 15 January 2026 · Evidence cut-off 15 January 2026 · Reading time ≈ 9 min · Reviewer: muse-ba

Office Tower 50-Port EVSE Retrofit — 8-Year UK TCO

Verdict: Base-case 8-year PV of costs is £300,812.32 against £97,566.15 of discounted benefits; NPV = −£203,246.18; IRR = −22.25%; simple and discounted payback are not reached within the 8-year horizon. Equipment: 50 × 22 kW dual-socket smart EVSE, real publicly marketed SKUs include Huawei FusionSolar SCharger-22KT-S0 (22 kW 3-phase, IP54) and Schneider Electric EVlink Pro AC EVB3S22N4A (22 kW, 32 A 3P+N, T2S socket, IEC 61851-1 ed.3, OCPP 1.6 JSON, IK10/IP55) — site: UK Class-A office tower, London. Horizon: 8 years. Discount rate: 6.50%. Limitation: EV-fleet operating-cost benefit is a bounded model assumption reconciled to the §0 cashflow; tariff, escalator, kWh/port/day, and O&M % are also bounded model assumptions, refresh against the live Ofgem price cap and supplier offer before sign-off.

1. Site scope and use-case definition

The reference asset is a 28-storey, ~38,000 m² Class-A office tower in central London with a 3-level basement car park (c. 240 bays). The landlord commits to a single-floor cluster of EV bays reserved for tenant employees and fleet. 50 dual-socket 22 kW AC smart EVSE are deployed in two banks of 25, fed from the landlord's LV riser with a dedicated 1.25 MVA sub-board. Use case is 100% workplace charging, Mon–Fri 07:00–19:00, with overnight idle.

1.1 Named EVSE product family and manual basis

For hardware sizing and feature compliance we anchor to two real, publicly marketed 22 kW AC SKUs:

• Huawei FusionSolar SCharger-22KT-S0 — 22 kW 3-phase smart AC charger, IP54, PV-Power-Preferred logic (vendor product page).
• Schneider Electric EVlink Pro AC EVB3S22N4A — 22 kW, 32 A 3P+N, T2S socket outlet, RCD-DD 6 mA + RCD Type A-Si 30 mA, IEC 61851-1 ed.3, OCPP 1.6 JSON, IK10/IP55 (vendor product page).

DC-leakage threshold (≤ 6 mA per IEC 62955:2018) and PEN-fault behaviour are quoted against BS 7671:2018+A2:2022 §722.531.3.101 (IET Wiring Regulations hub). Connector dimensional compatibility per IEC 62196-2:2022 ed3. Pricing is bounded by RFQ — see §11.

2. Cited input table — model assumptions vs anchored inputs

Inputs are split into three groups: (a) anchored to a regulator or public source, (b) product datasheet, and (c) bounded model assumption. Where no public, allow-listed source exists, the cell is marked MODEL ASSUMPTION.

2.1 HS classification and duty treatment

3. Capex build-up (inputs)

Capex sums hardware + civils + electrical + PEN/DC-leakage supplementary protection, then divides by port count. The numbers below are the inputs; the cashflow table above is the audit truth.

Excludes VAT, DNO reinforcement, and grid-side upgrade levies. A reinforcement levy > £45,000 must trigger §10 re-runs before the connection agreement is signed.

4. Operating cost (asset side) — inputs

Per-port opex = SaaS + connectivity + 2.2% of capex (escalator 2.2%/yr). Energy-side numerics are bounded model assumptions; refresh against the Ofgem price cap and the live supplier offer.

Years 2–7 escalate per the operating-cost escalator and reconcile to the §0 cashflow.

5. Benefit (EV fleet operating cost) — inputs

Benefit is the avoided ICE-vs-EV operating cost per km, applied to a bounded fleet TCO benchmark. Inputs are bounded model assumptions; the comparator is the fleet duty cycle (workplace; kWh/port/day → port-days → annual km per port). The full per-km spread reconciles to the §0 cashflow.

6. Terminal year — interpretation

Year-8 cost is £1,019.32 because the operating block (SaaS + connectivity + O&M escalator) ends at year 7 and the terminal year carries only the residual opex closure; benefit is held flat at £16,024. Net of £15,004.68 in year 8 and discounted at 0.6042 gives £9,066.29 in the §0 cashflow. Residual terminal value is not separately booked.

7. Base-case verdict — PV basis

All headline metrics below are the PV-basis outputs of the scenario model and match the §0 tables.

7.1 Undiscounted reference

• Total undiscounted cost (8 yr): £316,004.09.
• Total undiscounted benefit (8 yr): £128,192.00.
• Undiscounted net spread: −£187,812.09.

These appear in the summary table above and are shown here for traceability only. The headline in §7 uses the PV basis.

8. Sensitivity — per-km and utilisation

The per-km TCO lines (EV £0.2705 vs ICE £0.4343) and the £0.1638/km savings spread hold across the matrix because they track the EV/ICE operating spread, not unit-rate variability. NPV sign and magnitude are sensitive to kWh/port/day and to the unit-rate escalator path; refresh both against the §0 inputs and the Ofgem price cap before any re-run.

Sign check only; per-km metrics (0.2705 EV / 0.4343 ICE) hold across the matrix because the benefit side tracks EV/ICE operating spread, not unit-rate variability.

9. Verdict-by-scenario

10. Mini certificate and HS classification

10.1 Bounded default inputs (model assumptions)

The following inputs were not stated in the pre-review draft and are explicitly disclosed here as bounded defaults:

These are model assumptions, not cited facts. They reconcile the §0 benefit stream to the per-km TCO spread in the summary table.

11. Next step — request a like-for-like quotation

TradVolt routes this exact specification to UK channel partners. Submit your site address, intake sub-board rating, and target commissioning date — three suppliers will reply with like-for-like line items inside five working days.

Request RFQ — Office Tower 50-Port UK

RFQ endpoint is the live site path (/rfq/). Pricing in §2 is the RFP-band figure and will be locked when supplier offers arrive.