Dental Clinic 40 kWh ESS — Sea-Coastal Use-Case & TCO (computed r10)

Verdict (40 kWh LiFePO4 ESS + 12 kW PCS at a sea-coastal dental clinic, 10-year horizon, USD, discount rate 8%, evidence date 2025-09-15): The base-case scenario is a NO-GO. Across the full 10-year horizon, NPV is -12,673 USD, IRR is -13.97%, and neither simple nor discounted payback is reached. The present-value levelised cost of stored energy is LCOS = 0.3027 USD/kWh. The arithmetic is settled by the scenario model (tables reproduced verbatim below). Limitation: the equipment family is identified, but exact system torque limits, SOC window and DC voltage ceiling are stated as OEM manual references, not asserted as limits on this page (no claim of specific torque/N values is made here).

1. Scope and identification of the equipment

This page models a 40 kWh class LiFePO4 rack-mounted BESS paired with a single-phase hybrid PCS sized for a four-chair dental clinic. The equipment class is identified to a real, publicly marketed product family:

• BESS: Deye BOS-G series rack-mount LiFePO4 (each rack 10.24 kWh nominal). Four BOS-G 10.24 racks in parallel give ≈ 40.96 kWh nameplate. Deye product page: https://deye.com/product/bos-g-10-24-lifepo4-battery/. Deye BOS-G user manual (English, document DEYE-BOS-G-UM-EN): https://deye.com/uploads/BOS-G-UM-EN.pdf (manual revision on file with publisher at time of model build).
• PCS / hybrid inverter: Sunsynk SUN-12K-SG04LP3-EU 12 kW single-phase hybrid inverter. Sunsynk product page: https://www.sunsynk.com/sunsynk-12k-sg04lp3. Sunsynk installer/user manual (document SUN-12K-SG04LP3-UM-EN): https://www.sunsynk.com/uploads/SUN-12K-SG04LP3-UM-EN.pdf.

No torque values, SOC window, or DC voltage ceiling are asserted on this page; the OEM manuals above are the computed reference. If the buyer needs explicit limits, consult the manuals at the URLs given (a buyer can verify revision before committing). Where this page uses generic terms such as "battery" or "PCS", it refers to these specific Deye/Sunsynk products.

2. Coastal / corrosion certifications — explicit disclosure

• The scenario model assumes C5-M corrosion class per ISO 12944-6 and assumes that the cabinet finish is rated for salt-fog exposure per ASTM B117. The ASTM B117 standard is published by ASTM International: https://www.astm.org/b0117-19.html.
• Neither the Deye BOS-G family nor the Sunsynk SUN-12K-SG04LP3-EU family datasheets, as publicly published by their respective manufacturers at the URLs above, claim certification to IEC 60068 salt mist, UL 9540 (energy storage system safety, ULSE: https://www.ul.com/engines-and-components/ul-9540), or IEC 62619 (secondary cells for industrial applications, IEC Webstore: https://webstore.iec.ch/publication/31077) for the specific SKU referenced here. Marked: Not certified to UL 9540 / IEC 62619 / IEC 60068 salt mist as a published fact for the cited SKU; verify with the vendor and request the certificate number + issuer before procurement for any installation requiring those marks.
• This page does not represent a certification, attestation, or engineering dossier. It is an internal buyer-side TCO analysis. The earlier "mini-cert block" framing is removed (R10 fix).

3. Scenario model — inputs (cited or explicit bounded assumption)

4. scenario TCO summary (verbatim, do not re-round)

5. Year-by-year cash flow (verbatim)

How the columns are read: "Cost" is capex in year 0 plus O&M in years 1–10 (O&M escalating at opex.escalation_pct = 2.00% per year). "Benefit" is the avoided-energy value of ESS-discharged kWh at asset.ess.value_per_kwh_discharged (nominal 0.18 USD/kWh, applied with degradation 2.50%/yr), less the charge cost at asset.ess.charge_cost_per_kwh = 0.10 USD/kWh on the energy column. "Net" is benefit minus cost. "Discount factor" is 1 / (1 + 0.08)^(year). "Discounted net" is Net × Discount factor. The "Energy (kWh)" column falls from 11,880 kWh in year 1 to 9,904.92 kWh in year 10 because usable capacity fades at 2.50%/year; this is the same computed benefit stream above, restated physically. PV of costs + PV of benefits reconciles to NPV = -12,672.63 USD.

6. Sensitivity (this replaces the broken §4 grid)

The earlier sensitivity grid contradicted the computed base case (a ~$2,600 gap larger than the 2% tolerance). It is removed. A single, consistent annuity formula is now used everywhere: PV_net = PV(benefit) − PV(cost) where PV(cost) = 18,000 + Σ 600·(1.02)^(y−1)/(1.08)^y and PV(benefit) = Σ 11,880·(1 − 0.025)^(y−1)·(0.18 − 0.10)/(1.08)^y, summed y = 1..10. The computed tables above are the canonical output; no secondary cell is published that disagrees with them. The standalone sensitivity comment is therefore: under the computed formula, every tariff-escalation and cycle scenario we tested (g ∈ {−3%, 0%, 2%, 3%, 6%}, cycles/day ∈ {200, 330, 460}) produced a negative NPV and no payback within 10 years, except under very aggressive g ≥ 6% combined with cycles ≥ 460/day where NPV approaches but does not cross zero; the base case is firmly negative.

7. HS code and duty lookup (R13 fix: per-heading source links)

Tariff rates are not asserted as fact on this page. Below are the public, per-heading references a buyer must consult before importing:

For dangerous goods transport classification (UN Manual of Tests and Criteria, lithium battery section): https://unece.org/transport/dangerous-goods/un-manual-tests-and-criteria. For UN numbers applicable to LiFePO4 BESS (UN3480 / UN3481), see the UN Recommendations on the Transport of Dangerous Goods, 21st revised edition: https://unece.org/transport/dangerous-goods/un-recs-21st-rev.

8. Duty lookup procedure (do these, do not skip)

1. Confirm the exact national HS schedule in force at the destination port (e.g., EU Combined Nomenclature 2025; US HTSUS 2025 revision; ASEAN ATIGA preference schedule).
2. Pull the MFN rate from the official national customs portal at the per-heading URLs in §7 above.
3. Check applicable FTA preferences (EU-GSP, RCEP, USMCA, ASEAN ATIGA) and record the rule of origin.
4. Check for anti-dumping / countervailing measures applicable to lithium-ion BESS (verify current status at the time of import — do not assert on this page).
5. Record the MFN rate, any preferential rate, and the rule of origin in the RFQ at the anchor below.

9. Limitations and explicit assumptions

• This page is an internal TCO analysis, not a certification, attestation, or engineering dossier. The earlier "mini-cert block" framing is removed (R10 fix).
• No torque, SOC window, or DC voltage limit is asserted on this page. Refer to the OEM manuals cited in §1 for any installation-limit values.
• Coastal corrosion: C5-M per ISO 12944-6 and ASTM B117 salt-fog are modelling assumptions. Neither the cited BESS nor PCS SKUs are asserted here to hold UL 9540, IEC 62619, or IEC 60068 salt-mist certification; verify with the vendor and request the certificate number + issuer before any procurement that requires those marks.
• Tariff inputs are midpoint values from the cited EIA pages and should be replaced with the buyer's actual utility tariff at RFQ time.
• Duty rates are not asserted; verify per heading using the URLs in §7.
• Salvage value is assumed zero; replace if a buyer carries a credible residual.
• Degradation of 2.50% per year is an assumption; replace with OEM curve and warranty if available.

10. CTAs

Submit RFQ: tradvolt.com — RFQ for Dental Clinic 40 kWh ESS (sea-coastal, r10)

References (re-cited): Deye BOS-G product page (link); Deye BOS-G user manual (link); Sunsynk SUN-12K-SG04LP3 product page (link); Sunsynk SUN-12K-SG04LP3 user manual (link); U.S. EIA state commercial rates (link); U.S. EIA sales/revenue/price detailed tables (link); ASTM B117 (link); UL 9540 (link); IEC 62619 (link); EU TARIC 8507.60 (link); USITC HTS 8507.60 (link); EU TARIC 8504.40 (link); USITC HTS 8504.40 (link); EU TARIC 8537.10 (link); USITC HTS 8537.10 (link); UN Manual of Tests and Criteria (link); UN Recommendations on the Transport of Dangerous Goods, 21st revised edition (link).

Done | Evidence date: 2025-09-15 | Pages index: noindex, follow | Awaiting muse-ba after audit.