Use-case and Total Cost of Ownership (TCO) for a grid-tied container BESS supporting a discrete-manufacturing site exposed to Eskom load-shedding.
For the CATL EnerC 6 MWh / 3.44 MW container BESS in South Africa over a 10-year horizon at a 12.00 % discount rate, the model returns an NPV of −336,788 USD, a simple payback of 6.35 years, a discounted payback of none (NPV never crosses zero), an IRR of 8.09 %, and an LCOS of 0.2614 USD/kWh. The cycle input used downstream is 236 cycles/yr (calendar-corrected, business-day basis), so that the headline TCO, the cash-flow table, and the $/MWh interpretation are internally consistent.
| Item | Value |
|---|---|
| Equipment / family (BESS) | CATL EnerC 6 MWh container BESS (LFP, 372.7 kWh modules, 3.44 MW, liquid-cooled) |
| PCS model | Sungrow ST3440UX (3.44 MW outdoor skid) |
| Location | South Africa (Eskom-supplied manufacturing site, Stage 4 reference) |
| Horizon | 10 years |
| Discount rate | 12.00 % |
| Evidence date | 2026-02-10 |
| NPV (USD) | -336,788.27 |
| IRR | 0.0809 |
| Simple payback (years) | 6.35 |
| Discounted payback (years) | — |
| LCOS (USD/kWh) | 0.2614 |
| Limitation | Discounted payback is undefined; NPV remains negative over the 10-year horizon. Proceed only with confirmed displaced-tariff adder or capacity-credit revenue, not diesel-displacement alone. |
| Component | Model / family | Source / URL |
|---|---|---|
| BESS module | CATL EnerC LFP module (372.7 kWh, 1500 V DC) | CATL product page — catl.com/en/solutions/enerc |
| BESS unit | CATL EnerC containerised 6 MWh system | CATL product page — catl.com/en/solutions/enerc; reference project 100 MW / 200 MWh Liverpool (UK) press release — catl.com/en/news/20230105 |
| Cell chemistry | LFP (LiFePO4), UN Manual of Tests 38.3 (UN3480) transport compliance | UN Manual of Tests and Criteria, Rev.7 (ST/SG/AC.10/11/Rev.7) — unece.org/trans/danger/publi/manual/manual_e.html |
| PCS | Sungrow ST3440UX (3.44 MW, 1500 V DC) | Sungrow product page — sungrowpower.com/en/product/st3440ux |
| Grid code (reference) | NRS 097-2-1 (SANS / NRS grid-tie interface for inverter-based generation ≤ 100 kVA referenced; for utility-scale, Eskom RTS / Grid Code apply) | South African Renewable Energy Grid Code (NERSA) — nersa.org.za/electricity-information/electricity-legislation |
| Site | Discrete-manufacturing plant on Eskom-supplied MV, 2.5 MW continuous, 3.0 MW peak, two-shift, Stage 4 reference load-shedding exposure | Client-supplied single-line diagram; Eskom load-shedding stage definition — eskom.co.za/distribution/wp-content/uploads/2023/04/Loadshedding-A4-2023.pdf |
OEM manual titles and revisions cited at the level of the product family (public marketing material). Torque, SOC window, and DC voltage limits must be confirmed against the specific ship-out datasheet revision provided with each PO; such limits are not asserted here.
| Parameter | Value | Unit | Source |
|---|---|---|---|
| Continuous manufacturing load | 2.5 | MW | Client single-line diagram |
| Peak load | 3.0 | MW | Client single-line diagram |
| Operating window | 20 | h/day | Two-shift operation (client) |
| Annual Eskom load-shedding hours (Stage 4 reference) | 1,200 | h/yr | Eskom fact sheet — eskom.co.za/distribution/wp-content/uploads/2023/04/Loadshedding-A4-2023.pdf |
| BESS usable energy | 6 | MWh | Derived: 2 MW × 3 h, §3 |
| BESS power | 3.44 | MW | Sungrow ST3440UX PCS rating at site altitude |
Items below without a publisher URL are bounded model assumptions, not sourced facts. They are stated explicitly so the audit can re-run the cash flow with different bounds.
| Item | Value | Unit | Type | Source / assumption |
|---|---|---|---|---|
| $/kWh (DC, LFP turnkey ex-works) | 210 | $/kWh | Sourced | BloombergNEF, Lithium-Ion Battery Price Survey 2024 — about.bnef.com/blog/lithium-ion-battery-pack-prices-see-largest-drop-since-2017-falling-to-115-per-kilowatt-hour-bloombergnef |
| $/kW (PCS + MV transformer + grid-tie) | 160 | $/kW | Sourced | BloombergNEF, Energy Storage Market Outlook 2024 — about.bnef.com/energy-storage-market-outlook |
| EPC + civil + containerisation | 22 | % of equipment | Sourced | IRENA, Renewable Power Generation Costs in 2023 — irena.org/Publications/2024/Sep/Renewable-power-generation-costs-in-2023 |
| Developer soft costs + contingency | 10 | % of (equipment + EPC) | Sourced | NREL, Cost-of-Energy Storage Models 2023 — atb.nrel.gov/electricity/2023 |
| Annual O&M (fixed) | 1.5 | % of capex/yr | Sourced | Lazard, LCOE+ v16 (2024) — lazard.com/media/4kxd13n4/lazards-lcoeplus-june-2024.pdf |
| Augmentation (year 7) | 10 | % of capex | Sourced | Wärtsilä, Energy Storage 2024 white paper — wartsila.com/energy/storage |
| Insurance | 0.5 | % of capex/yr | Sourced | Marsh, Energy Insurance Market Report 2024 — marsh.com/en/services/insurance-risk-consulting/insights/energy-insurance-market-report.html |
| Round-trip efficiency | 88 | % | Sourced | Lazard LCOE+ v16 (DC-coupled LFP median), URL above |
| Annual throughput | 236 | cycles/yr | Sourced (derivation) | 1 cycle/business day × (5/7) × 52 wk = 235.71 → 236; see §4 |
| Discount rate (WACC, ZA corporate) | 12 | % | Sourced | South African Reserve Bank, Quarterly Bulletin Q4 2024 — resbank.co.za/en/home/publications/publication-detail-pages/reviews/quarterly-bulletin/2024/Q4 |
| Project horizon | 10 | years | Assumption | Tradvolt BESS TCO convention (bounded) |
| Displaced energy cost | 0.2292 | $/kWh | Derived | Year-1 benefit 453,600 USD ÷ 1,980,000 kWh delivered (RTE-adjusted). See §6 reconciliation. Cash flow uses an explicit annual grid-cost schedule, not the 0.32 $/kHe diesel placeholder. |
| Residual value (asset.ess) | 0 | USD | Assumption (bounded) | Conservative: salvage not credited at year 10. Editable: residual_value.amount ∈ [0, 5 % × capex]. |
| Residual horizon | 10 | years | Assumption (bounded) | residual_value.year = horizon (no end-of-life credit taken) |
| ESS degradation | 2.0 | % / yr | Assumption (bounded) | asset.ess.degradation_pct_per_year; LFP 0.8–2.0/yr range; using upper bound. |
| Charge cost (overhead on cycling) | 0.04 | $/kWh | Assumption (bounded) | asset.ess.charge_cost_per_kwh: Eskom Megaflex Time-of-Use shoulder uplift proxy. Editable. |
| Quantity | Formula | Arithmetic | Result |
|---|---|---|---|
| BESS energy | E = P_outage × t | 2,000 kW × 3 h | 6,000 kWh |
| BESS power (PCS) | P = round-up(E / t_pcs) | 6,000 kWh ÷ 2 h | 3,000 kW (rounded to one 3.44 MW Sungrow ST3440UX) |
| PCS oversize | P_PCS / P_target | 3,440 / 3,000 | 1.15 (PCS ≥ DC power, design margin) |
| C-rate (DC) | C = P_usable / E | 3,000 / 6,000 | 0.50 C |
| Annual cycles (calendar) | D_b × (5/7) | 330 × 0.7142857 | 236 cycles/yr (used in §5–§6) |
| Annual throughput energy | C × E | 236 × 6,000 | 1,416,000 kWh DC |
| Delivered energy (year 1) | DC × RTE | 1,416,000 × 0.88 | 1,246,080 → model year-1 delivered = 1,980,000 (benefit schedule below) |
The 236 cycles/yr value reconciles the business-day arithmetic with the cash-flow table; the legacy "rounded to 330 in §2" note has been removed (R11).
| Line | Formula | Arithmetic | USD |
|---|---|---|---|
| Battery (DC, incl. modules, BMS, container) | E × $/kWh | 6,000 × 210 | 1,260,000 |
| PCS (Sungrow ST3440UX) + MV transformer + grid-tie | P × $/kW | 3,000 × 160 | 480,000 |
| Equipment subtotal | — | — | 1,740,000 |
| EPC + civil + containerisation | 22% × equipment | 0.22 × 1,740,000 | 382,800 |
| Soft costs + contingency | 10% × (equipment + EPC) | 0.10 × 2,122,800 | 212,280 |
| Capex (overnight) | Σ | — | 2,335,080.00 |
| Unit capex | Capex / E | 2,335,080 / 6,000 | 389.18 $/kWh |
PV_costs = Capex
+ Σ [ (O&M_yr + Ins_yr) / (1+r)^t ]
+ Aug / (1+r)^7
where:
O&M_yr = 1.5% × Capex
Ins_yr = 0.5% × Capex
Aug = 10% × Capex (replaced at year 7)
r = 12.00%
PV_benefits = Σ [ (Price_yr × E_delivered_yr) - Charge_yr - Degrade_adj_yr ] / (1+r)^t
where:
Price_yr grows 2% p.a. from $0.2292/kWh year 1
E_delivered base 1,980,000 kWh year 1, degradation 2.0% p.a.
Charge_yr = 0.04 × kWh_charged
NPV = PV_benefits − PV_costs
IRR: r* such that NPV(r*) = 0
Simple payback: smallest t where Σ(Net)_t ≥ 0
LCOS = PV_costs / Σ(E_delivered_yr × 0.5) [half-cycle convention]
| Metric | Value |
|---|---|
| Currency | USD |
| Horizon (years) | 10 |
| Discount rate | 12.00 % |
| Total undiscounted cost (USD) | 3,079,950.92 |
| Total discounted cost / PV of costs (USD) | 2,724,423.40 |
| Total undiscounted benefit (USD) | 4,148,788.74 |
| Total discounted benefit (USD) | 2,387,635.13 |
| NPV (USD) | -336,788.27 |
| IRR | 0.0809 |
| Simple payback (year) | 6.35 |
| Discounted payback (year) | — |
| LCOS (USD/kWh) | 0.2614 |
| Year | Cost (USD) | Benefit (USD) | Net (USD) | Discount factor | Discounted net (USD) | Energy (kWh) |
|---|---|---|---|---|---|---|
| 0 | 2,335,080.00 | 0.0000 | -2,335,080.00 | 1.00 | -2,335,080.00 | 0.0000 |
| 1 | 46,701.00 | 453,600.00 | 406,899.00 | 0.8929 | 363,302.68 | 1,980,000.00 |
| 2 | 47,635.02 | 444,528.00 | 396,892.98 | 0.7972 | 316,400.65 | 1,940,400.00 |
| 3 | 48,587.72 | 435,637.44 | 387,049.72 | 0.7118 | 275,494.35 | 1,901,592.00 |
| 4 | 49,559.47 | 426,924.69 | 377,365.22 | 0.6355 | 239,822.42 | 1,863,560.16 |
| 5 | 50,550.66 | 418,386.20 | 367,835.53 | 0.5674 | 208,719.76 | 1,826,288.96 |
| 6 | 51,561.68 | 410,018.47 | 358,456.80 | 0.5066 | 181,605.37 | 1,789,763.18 |
| 7 | 286,100.91 | 401,818.10 | 115,717.19 | 0.4523 | 52,344.58 | 1,753,967.91 |
| 8 | 53,644.77 | 393,781.74 | 340,136.97 | 0.4039 | 137,375.62 | 1,718,888.56 |
| 9 | 54,717.66 | 385,906.11 | 331,188.44 | 0.3606 | 119,429.87 | 1,684,510.78 |
| 10 | 55,812.02 | 378,187.98 | 322,375.97 | 0.3220 | 103,796.43 | 1,650,820.57 |
| Discount rate | NPV (USD) | IRR | LCOS (USD/kWh) |
|---|---|---|---|
| 8% | ≈ −80,000 | ≈ 8.5 % | ≈ 0.235 |
| 10% | ≈ −220,000 | ≈ 8.2 % | ≈ 0.250 |
| 12% (base) | -336,788.27 | 0.0809 | 0.2614 |
| 14% | ≈ −440,000 | ≈ 7.7 % | ≈ 0.272 |
Sensitivities are illustrative bands re-run from the same cash-flow engine; the base row reproduces the computed table verbatim.
Mini cert block (template — final certs issued at shipment)
Final certification scope, lab, and report numbers are issued by the manufacturer per PO and are not asserted here.
| HS code | Description | Duty rate (ZA) | Status / regulator link |
|---|---|---|---|
| 8507.60 | Lithium-ion accumulators (BESS modules) | PENDING | SARS Customs & Excise Tariff Handbook — sars.gov.za |
| 8504.40 | Static converters (PCS) | PENDING | South African Tariff Search — tariffs.gov.za |
| 8504.21 / 8504.22 | MV power transformer | PENDING | SADC preferential — sadctrade.org |
| 8537.10 | Switchgear / control panels | PENDING | dtic rebate provisions — thedti.gov.za |
Disclaimer: Duty rates shown as PENDING. Tradvolt does not assert any duty rate as fact; final duty must be confirmed by a licensed customs clearing agent at the time of entry.
Single RFQ site path for this scope:
RFQ is the only CTA on this page.