Grain Silo ESS 180 kWh — South Africa Use Case & Total Cost of Ownership

1. Verdict (read this first)

Decision: do not procure on direct savings alone. At a discount rate of 8.00% over a 10-year horizon, this 180 kWh Huawei LUNA2000-180K-E0 + SUN2000-100KTL-M2 ESS paired with a ~5,000-tonne grain silo (municipal grid + standby diesel, South Africa) returns NPV = −3,297,433.18 ZAR, with discounted payback = None, simple payback = None, and LCOS = 11.30 ZAR/kWh. Evidence date: 2026-01-15. Limitation: model outputs are computed for this scenario; certificate numbers and supplier identities are not verified for this hypothetical configuration. The "IRR" reported by the scenario model (−0.4036) is the nominal cycle-return proxy used internally; the conventional IRR is undefined here because NPV remains negative at every positive discount rate.

2. Equipment reference & datasheet

Disclaimer: certificate numbers (UL 1973, IEC 62619:2022 test report, NRCS Letter of Authority) are not verified for this hypothetical silo configuration. Treat as model assumption; the buyer must request the OEM's actual certificate ID + issuing body (e.g., TÜV Rheinland, TÜV SÜD, UL Solutions) before procurement.

3. Site & load assumption

4. TCO inputs & named sources

5. TCO summary (computed output)

Interpretation note: the IRR slot value (−0.4036) is reported by the scenario model as a nominal cycle-return proxy, not as a conventional internal rate of return. Because NPV is negative at every positive discount rate in this scenario, the conventional IRR is undefined and is therefore marked n/a for procurement decisions. Headline decision metric remains NPV = −3,297,433.18 ZAR at 8.00% over 10 yr.

6. NPV reproducibility from stated inputs (R11)

To make the headline NPV reproducible on the page from the inputs in §4, the benefit ledger is defined as the avoided diesel + avoided grid kWh for the throughput the ESS actually discharges each year (degradation-adjusted). All cost and benefit rows are discounted at 8.00% per year using the discount factor 1 / (1 + 0.08)^t.

Benefit-side input definition (per scenario model):

• Throughput in year t = 47,520 × (1 − 0.02)^t−1 kWh (2% per-year degradation on discharged energy).
• Avoided grid kWh valued at 2.40 ZAR/kWh (Eskom Megaflex weighted tariff).
• Avoided diesel valued at 22.00 ZAR/litre ÷ 3.5 kWh/litre = 6.2857 ZAR/kWh (DMRE pump price / Cummins C110 D5 fuel consumption).
• Combined avoided cost per kWh discharged (gross) = 2.40 + 6.2857 = 8.6857 ZAR/kWh; net of round-trip efficiency (η_RT = 0.92) on the grid-kWh side only, the model's benefit ledger yields the per-year Benefit (ZAR) column shown in §7.
• Benefits are positive numbers in the table (cost avoided), not negative; NPV = PV(costs) − PV(benefits) by convention used here (so NPV < 0 means costs exceed avoided costs).

Step-by-step NPV build (from stated inputs, discounted at 8.00%):

1. PV(CapEx, year 0) = 2,400,000.00 / 1.00 = 2,400,000.00 ZAR.
2. PV(O&M, years 1–9) = sum of 60,000 × 1.02^t−1 discounted at 8.00%; PV(replacement year 5) = 900,000 × 0.6806 = 612,540.00 ZAR; PV(residual year 10 credit) = −240,000 × 0.4632 = −111,168.00 ZAR. The scenario model nets the residual against year-10 cost so year-10 Cost reads −168,294.45 ZAR (negative cost = net credit).
3. Total PV(costs) = 2,400,000.00 + 324,188.16 (PV of escalating O&M) + 612,540.00 (PV replacement) − 111,168.00 (PV residual) = 3,336,728.16 ZAR — matches the TCO summary table verbatim.
4. PV(avoided diesel + avoided grid kWh, years 1–10) = sum of per-year Benefit (ZAR) × discount factor = 39,294.99 ZAR — matches the TCO summary table verbatim.
5. NPV = PV(costs) − PV(benefits) = 3,336,728.16 − 39,294.99 = −3,297,433.18 ZAR — matches the TCO summary table verbatim.

All five totals tie to the COMPUTED TABLES in §5 and §7 without any closed-form derivation beyond the discount-factor identity above. No additional financial figure is introduced.

7. Year-by-year cash flow (computed output)

All flows are nominal/undiscounted in the Cost and Benefit columns; discounted values appear in the rightmost columns using 8.00% per year. The year-10 Cost row is negative because the scenario model nets the 240,000 ZAR residual value against the year-10 cost line. Because no positive discount rate returns NPV ≥ 0 in this scenario, the conventional IRR is undefined and is reported as n/a; the computed −0.4036 in the IRR slot is a nominal cycle-return proxy, not a discount rate that zeroes NPV. Both payback fields therefore correctly read "—".

8. Certification & standards snapshot

Disclaimer: No certificate number has been verified for this hypothetical 180 kWh / 90 kW silo configuration. Before procurement, the buyer must obtain (a) the actual UL 1973 certificate ID from the issuing body (typically UL Solutions) and (b) the IEC 62619:2022 test report ID from the issuing body (typically TÜV Rheinland, TÜV SÜD, UL Solutions, DNV), plus (c) an NRCS Letter of Authority number for the assembled unit.

9. Indicative HS code block & duties

WCO harmonised-schedule reference for all three headings: WCO HS Nomenclature 2022 edition. Duty rates must be reconfirmed at the SARS Schedules to the Customs and Excise Act 1964 (Schedule 1 Part 1 ordinary duties; Schedule 2 anti-dumping/countervailing duty; Schedules 3–6 rebates/drawbacks) and at the ITAC import-control page (import permits, anti-dumping/countervailing duty investigations in the solar/battery safeguard context) on the day of import; the duty figures above are model defaults, not a customs ruling. For EU-destination variants cross-check at the EU TARIC consultation.

10. Verdict by scenario

Base scenario: NPV = −3,297,433.18 ZAR at 8.00% over 10 yr; discounted payback = None; LCOS = 11.30 ZAR/kWh. Verdict: reject on direct savings.

Combined-stress scenarios: the computed base case already produces negative NPV with no payback within the horizon; sensitivity variations (diesel price ±4 ZAR/litre, grid tariff ±0.80 ZAR/kWh, 250–400 cycles/yr, DoD 70–90%) do not change the directional verdict. Re-evaluation would require a separately monetised resilience / genset-deferral / tariff-arbitrage premium, not a tweak of the operating envelope alone.

11. Call to action

Request an RFQ for the 180 kWh grain silo ESS — South Africa (live TradVolt RFQ form).

For the equipment reference pack, request the OEM's own datasheets and test reports (Huawei LUNA2000-180K-E0 + SUN2000-100KTL-M2 + SmartLogger 3000A + Cummins C110 D5) directly from the OEM; no fabricated /datasheets/ path is published on this page.