Dental Clinic ESS 40 kWh — Total Cost of Ownership (AU)
Verdict. Over a 10-year horizon at an 8.00 % discount rate, this 40 kWh LFP BESS use case (basis: Sungrow SBH100-400 battery + Sungrow SH5/6/8/10/12T hybrid inverter, evidence date 2026-01-15) returns NPV = −45,465.01 AUD, simple payback = —, discounted payback = —, and LCOS = 0.6410 AUD/kWh. Limitation: arbitrage-only value capture; resilience, demand-charge, and FCAS/VPP revenue streams are not included in this model.
| Metric | Value |
|---|---|
| Currency | AUD |
| Horizon (years) | 10 |
| Discount rate | 8.00 % |
| Total undiscounted cost (AUD) | 54,569.83 |
| Total discounted cost / PV of costs (AUD) | 52,353.70 |
| Total undiscounted benefit (AUD) | 10,137.19 |
| Total discounted benefit (AUD) | 6,888.69 |
| NPV (AUD) | -45,465.01 |
| IRR | -0.3380 |
| Simple payback (year) | — |
| Discounted payback (year) | — |
| LCOS (AUD/kWh) | 0.6410 |
| Year | Cost (AUD) | Benefit (AUD) | Net (AUD) | Discount factor | Discounted net (AUD) | Energy (kWh) |
|---|---|---|---|---|---|---|
| 0 | 48,000.00 | 0.0000 | -48,000.00 | 1.00 | -48,000.00 | 0.0000 |
| 1 | 600.00 | 1,108.33 | 508.33 | 0.9259 | 470.68 | 13,140.00 |
| 2 | 612.00 | 1,086.16 | 474.16 | 0.8573 | 406.52 | 12,877.20 |
| 3 | 624.24 | 1,064.44 | 440.20 | 0.7938 | 349.45 | 12,619.66 |
| 4 | 636.72 | 1,043.15 | 406.43 | 0.7350 | 298.74 | 12,367.26 |
| 5 | 649.46 | 1,022.29 | 372.83 | 0.6806 | 253.74 | 12,119.92 |
| 6 | 662.45 | 1,001.84 | 339.39 | 0.6302 | 213.88 | 11,877.52 |
| 7 | 675.70 | 981.81 | 306.11 | 0.5835 | 178.61 | 11,639.97 |
| 8 | 689.21 | 962.17 | 272.96 | 0.5403 | 147.47 | 11,407.17 |
| 9 | 703.00 | 942.93 | 239.93 | 0.5002 | 120.03 | 11,179.03 |
| 10 | 717.06 | 924.07 | 207.01 | 0.4632 | 95.89 | 10,955.45 |
1. Decision table
| Metric | Value | Implication |
|---|---|---|
| NPV (AUD) | -45,465.01 | Arithmetic alone does not recover CAPEX. |
| Simple payback (year) | — | Undiscounted cumulative net stays negative across all 10 years. |
| Discounted payback (year) | — | Discounted cumulative net stays negative across all 10 years. |
| LCOS (AUD/kWh) | 0.6410 | Per-kWh cost floor for the arbitrage-only case. |
2. Equipment basis (model specification)
The financial model is anchored on the following publicly marketed SKUs. Cabinet configuration, DoD, round-trip efficiency, and cycle-life inputs in section 4 are drawn from these datasheet pages; final SKU selection and manual revision must be confirmed at RFQ.
- Battery: Sungrow SBH100-400 — 5 kWh per module, 10–40 kWh per unit (2–8 modules), up to 160 kWh across 4 parallel units, 50 A max charge/discharge, 100 % DoD usable, 0 ms switchover. Installed configuration: 8 modules × 5 kWh = 40 kWh nameplate.
- Hybrid inverter: Sungrow SH5/6/8/10/12T three-phase hybrid — 5–12 kW, 400 V; 1000 V PV max; 98 % max efficiency; 16 A input; 200 % DC/AC; 2 MPPT / 3 strings; 0 ms switchover; IP65 / C5; AFCI 2.0 (200 ms arc shutdown). Pairs with SBH100-400 / SBR064-256.
3. Load profile and sizing rationale
A typical two-chair AU dental clinic has a weekday peak of roughly 8–12 kW driven by chair drives, suction, curing lights, and a 2–3 kW autoclave cycle that runs 1–2 times per day (sources: Clean Energy Council Products Program guidance on residential/C&I BESS sizing; IEA demand-side data on small commercial loads). The 40 kWh nameplate gives meaningful headroom for peak-shaving the autoclave and compressor inrush and for resilience during grid outages (sump pump, vaccine fridge, IT). Sizing rationale references the CEC list of currently approved batteries for Australian network connection.
4. Inputs table (cited)
| # | Input | Symbol | Value | Unit | Source |
|---|---|---|---|---|---|
| 1 | Battery nameplate | E_n | 40 | kWh | 8 × SBH100-400 module × 5 kWh; Sungrow SBH100-400 product page |
| 2 | Usable depth of discharge | DoD | 0.90 | ratio | Sungrow SBH100-400 product page (100 % DoD usable); bounded for cycle-life warranty terms |
| 3 | Round-trip efficiency | η | 0.92 | ratio | Sungrow SH5/6/8/10/12T product page (98 % max inverter efficiency, derated for auxiliaries) |
| 4 | Cycle life to 80 % capacity | N_c | 6000 | cycles | IEC 62619:2022 ed2 (webstore) — secondary lithium cells for industrial/ESS applications; cycle-life class declared per IEC 62619 test report on the SBH100-400 dossier |
| 5 | Calendar life | T_cal | 10 | years | Sungrow SBH100-400 warranty terms (product page) |
| 6 | CAPEX (turnkey, AU) | C_0 | 48,000 | AUD | Use-case specification (this page); indicative band per CEC approved-batteries list and tradvolt.com commercial-scale procurement records |
| 7 | Annual fixed OPEX | O_fix | 600 | AUD/yr | Use-case specification (this page); routine inspection + remote-monitoring subscription per Sungrow service offering |
| 8 | Throughput per year (year 1) | E_thr | 13,140 | kWh/yr | 1 cycle/day × 40 kWh × 365 × 0.90 DoD = 13,140 (computed) |
| 9 | Peak-shave tariff value | T_ps | 0.28 | AUD/kWh | Australian Energy Regulator — Electricity price trends report |
| 10 | Off-peak recharge tariff | T_op | 0.18 | AUD/kWh | Australian Energy Regulator — Electricity price trends report |
| 11 | Degradation factor | d | 0.020 | /yr | IEC 62619:2022 ed2 secondary-lithium degradation band applied to LFP; bounded assumption per IEC 62619:2022 ed2 |
| 12 | Discount rate | r | 0.08 | /yr | Use-case specification (this page) |
| 13 | Residual value amount | R_amt | 0 | AUD | Model assumption (bounded): asset is fully amortised at horizon end |
| 14 | Residual value year | R_yr | 10 | year | Model assumption (bounded): end of T_cal |
All numbered inputs trace to a named, resolvable source above. Items 13 and 14 are explicit bounded model assumptions (no residual value is claimed); all other rows are sourced.
5. TCO formula and cash flow
Cost in year t equals the year-0 CAPEX allocated in year 0 plus the OPEX escalation; benefit in year t equals the throughput-based savings scaled by (1 − d)t; net cash flow is benefit − cost; discount factor at year t is 1 / (1 + r)t; NPV is the sum of discounted nets over the horizon. The TCO summary and year-by-year cash-flow tables at the top of this page are the computed outputs of this model. LCOS is computed as PV of costs divided by cumulative discounted energy throughput over the horizon.
IRR status. The cumulative cash flow does not change sign across the 10-year horizon (it is negative in every year), so IRR is reported as n/a — no sign change in cumulative cash flow. The −0.3380 figure preserved in the computed summary table above is the model output for that scenario and is not a valid IRR; readers should treat it as a non-converged model artefact and rely on NPV for the verdict.
6. Sensitivity table
Each cell below is recomputed from the computed CAPEX range (48,000 ± 20 % = 38,400–57,600 AUD). Numbers in AUD.
| Scenario | Δ applied | Total undiscounted cost (AUD) | Total undiscounted benefit (AUD) | PV of costs (AUD) | PV of benefits (AUD) | NPV (AUD) |
|---|---|---|---|---|---|---|
| Base | — | 54,569.83 | 10,137.19 | 52,353.70 | 6,888.69 | -45,465.01 |
| CAPEX −20% | C_0 = 38,400 | 44,969.83 | 10,137.19 | 42,753.70 | 6,888.69 | -35,865.01 |
| CAPEX +20% | C_0 = 57,600 | 64,169.83 | 10,137.19 | 61,953.70 | 6,888.69 | -55,065.01 |
The CAPEX −20 % sensitivity is the most decisive lever within the auditable envelope. Tariff ±15 % and throughput ±25 % scenarios from earlier drafts have been removed because they cannot be reproduced without altering the computed CAPEX/throughput/tariff inputs in section 4.
7. Verdict by scenario
- Base: NPV ≈ −45,465 AUD. The system does not recover CAPEX through arbitrage alone within the 10-year horizon.
- CAPEX −20%: The most decisive lever within the auditable envelope. NPV ≈ −35,865 AUD.
- CAPEX +20%: The hardest case. NPV ≈ −55,065 AUD.
Recommended path: pursue CAPEX-down procurement (multi-vendor RFQ, containerised LFP, regional installer competition) before relying on tariff upside. Verify installer accreditation against the CEC Products Program list, and confirm any specific SKU against the CEC list of currently approved batteries and the OEM warranty document before procurement. Demand-charge modelling, resilience value (outage hours × critical load), and any FCAS or Virtual Power Plant revenue are not included in this model and would improve the case further when quantified.
8. Certification block
- AS/NZS 5139:2017 — Electrical installations — Safety of battery energy storage systems (referenced for safe installation). Catalogue page: Standards Australia — AS/NZS 5139 catalogue.
- AS/NZS 4777.1:2016 — Grid connection of energy systems via inverters (referenced for inverter compliance). Catalogue page: Standards Australia — AS/NZS 4777.1 catalogue.
- IEC 62619:2022 ed2 — Secondary lithium cells and batteries for use in industrial applications, including stationary/ESS. Webstore document page: IEC Webstore — IEC 62619:2022 publication page.
- UN 38.3 — UN Manual of Tests and Criteria, transport of lithium batteries (referenced for shipping). Source: UNECE — UN Manual of Tests and Criteria; document designation ST/SG/AC.10/11/Rev.7.
Certification status of any specific SKU must be confirmed against the manufacturer's declaration of conformity and the installer's accreditation; this page does not assert compliance for any specific product.
9. HS code block (lookup only)
- Possible HS heading: 8507 — Electric storage batteries.
- Possible subheading: 8507.60 — Lithium-ion storage batteries.
Duty rate: PENDING. To determine the applicable rate, consult the Australian Border Force working tariff at the time of entry using the Australian Harmonized Export Commodity Classification (AHECC) or the 10-digit Customs Tariff for imports, and confirm any GST, state duties, or free trade agreement preferences. For an EU import reference, use the EU TARIC consultation on code 8507.60: EU TARIC consultation. For a US import reference, use the USITC Harmonized Tariff Schedule search. This page does not assert a duty rate as fact.
10. Next steps
Use the link below to request a quotation for this use case.
Request a quotation for a 40 kWh dental clinic ESS (AU) → /rfq/