Vertical: Solar BoS · Use-case: Plant Rooftop 350 kW · Lane: CN → UK · Horizon: 25 years · Discount rate: 8.00% · Currency: GBP · Evidence date: 2026-09-22
Verdict — DO NOT PROCEED on this 25-year horizon at an 8% discount rate. For the stated scenario (350 kW on-grid inverter on a UK plant rooftop, 420 kWp DC, ~378,000 kWh/yr, 70% self-consumption, 4% electricity-price escalation, 2% OpEx escalation, Year-1 imported tariff £0.30/kWh, Year-1 SEG export £0.075/kWh, initial CapEx band £1,050,000, initial annual OpEx £18,000, zero residual value at end of year 25), the scenario model returns NPV = −£1,492 (effectively zero, slightly negative), simple payback = 12.09 years, discounted payback = — (never within horizon), and LCOE = £0.3299 / kWh. Discounted payback is not reached inside 25 years at 8% WACC; the IRR is 7.99%, marginally below the 8.00% hurdle. The investment is on the knife-edge of acceptability — binding payback, IRR and LCOE will move sharply with the final CapEx band, the actual electricity-tariff path, and the confirmed HS national line.
Equipment: 3-phase string on-grid inverter in the 350 kW AC class (candidate OEM shortlist: Sungrow SG350HX, Growatt MAX 350 KTL3-XL2, Huawei SUN2000-330KTL-H1). Location: United Kingdom, plant rooftop C&I. Horizon: 25 years. Evidence date: 2026-09-22. Limitation: numbers below are MODEL-OUTPUT, illustrative, NOT A QUOTE — submit the RFQ for a binding quote.
| Decision metric | Value | Read |
|---|---|---|
| NPV (25 yr, 8% WACC) | −£1,492 | ≈ break-even, marginal NEGATIVE |
| IRR | 7.99% | Below 8.00% hurdle |
| Simple payback | 12.09 years | Inside horizon, but only just |
| Discounted payback | — (not reached) | NPV never crosses zero inside 25 yr |
| LCOE | £0.3299 / kWh | Compare to buy-tariff only |
B2B landed-cost and total-cost-of-ownership page for sourcing a three-phase 350 kW string on-grid solar inverter from a Chinese OEM and delivering it to a commercial / industrial rooftop in the United Kingdom. Built for asset owners, EPCs and procurement managers evaluating CN-sourced BoS components for G99 / UKCA compliant plants.
| Candidate OEM | Model / family | AC output (rated) | Datasheet / product page | Status on this page |
|---|---|---|---|---|
| Sungrow | SG350HX (3-phase string on-grid inverter, 1500 V DC, 12 MPPT) | 350 kW | Sungrow string inverter range (SG series) | Datasheet revision confirmed at RFQ |
| Growatt | MAX 350 KTL3-XL2 (3-phase string on-grid inverter, C&I class) | 350 kW | Growatt product portal (catalog) | Datasheet revision confirmed at RFQ |
| Huawei | SUN2000-330KTL-H1 (FusionSolar 3-phase string on-grid inverter, often paired to a 350 kW AC equivalent set) | 330 kW per unit | Huawei SUN2000-330KTL-H1 product page | Datasheet revision confirmed at RFQ |
All three are real, publicly marketed CN-OEM products in the 330–350 kW AC class. The exact datasheet revision and certificate numbers (UKCA, G99, IEC 62109-1:2010 / IEC 62109-2:2011 test reports) are pulled into the RFQ library per shipment. No invented SKUs or part numbers are used on this page.
| Parameter | Value (input) | Source / Assumption |
|---|---|---|
| Site type | Industrial / manufacturing plant rooftop, flat or low-pitch | Buyer-defined RFQ field |
| PV array (DC) | ~420 kWp (1.2× DC/AC ratio to limit clipping) | Model assumption (bounded default) |
| Inverter topology | Three-phase transformerless string on-grid inverter (1500 V DC class) | OEM datasheet category (see shortlist above) |
| Grid connection | 3-phase 400 V, >16 A per phase → G99 application required | ENA Engineering Recommendation G99 issue 1 amendment 9 (2024), see §6 |
| Target certifications | UKCA; IEC 62109-1:2010; IEC 62109-2:2011; ENA G99; EMC per EN 61000-6-2 / -6-4 family | UK gov.uk UKCA guidance; IEC catalogue |
| Export / revenue model | Self-consumption + SEG export for surplus kWh | Ofgem — Smart Export Guarantee (SEG) |
| Line item | Unit basis | Value (illustrative) | Notes |
|---|---|---|---|
| EXW unit price, 350 kW on-grid inverter (CN OEM, shortlist above) | per unit | PENDING — lookup | Price depends on SKU, brand tier, MOQ. Submit RFQ for firm quote. |
| Sea freight CN → UK port (Felixstowe / Southampton) | per unit (oversize) | PENDING — lookup | Confirmed against freight RFQ; oversize pallet rule per Incoterms 2020 CIF / FOB basis. |
| UK import duty | % of CIF | PENDING — lookup (HS national line = PENDING) | Apply rate from UK Global Tariff lookup for the confirmed 8-digit HS line (heading 8504.40 family). |
| VAT (post-customs) | 20% of (CIF + duty) | PENDING — lookup | Standard UK VAT 20% per HMRC notice 702 on imports. Postponed VAT accounting available. |
| Customs clearance + broker | flat per shipment | PENDING — lookup | Broker fee depends on Incoterm and entry type (CDS). |
| UK inland haulage (port → rooftop site) | per delivery | PENDING — lookup | Oversize load; Hiab on site may be required. |
| DC-side BoS (rails, DC cabling, MC4, PV connectors, combiner) | per kWp | PENDING — lookup | Quoted on RFQ; sized to ~420 kWp. |
| AC-side BoS (AC cabling, DC/AC isolators, SPDs, generation meter) | per system | PENDING — lookup | Quoted on RFQ. |
| EPC install, commissioning, G99 witness testing | per system | PENDING — lookup | Independent G99 witness test required for >16 A installations. |
| Insurance / contingency reserve | % of above | PENDING — lookup | Standard 5–10% contingency line. |
Every monetary line above is marked PENDING — lookup because binding values depend on SKU, MOQ, freight rates on the booking date and the confirmed HS national line. TradVolt returns firm values inside the 48-hour RFQ window. The modelled Year-0 CapEx input is £1,050,000 (illustrative band), which is the single figure the scenario TCO model uses to produce the tables in §4.
| Line item | Unit basis | Value (illustrative) | Notes |
|---|---|---|---|
| Preventive O&M (annual visual + thermography) | per system / yr | PENDING — lookup | Typically scheduled twice per year for C&I. |
| Inverter spare-parts reserve / swap pool | % of inverter CapEx / yr | PENDING — lookup | Includes fan replacement, DC board, AC SPD kits. |
| Monitoring subscription (cloud portal / SCADA) | per system / yr | PENDING — lookup | Optional OEM cloud or 3rd-party monitoring. |
| Insurance (property + business interruption) | % of total CapEx / yr | PENDING — lookup | Carrier-specific. |
| DNO fees / G99 ongoing charges | flat / yr | PENDING — lookup | DNOs may levy ongoing charges; site-specific. |
| Annual electricity price escalation (input) | % / yr | 4.0% (illustrative) | Editable in the RFQ; replaces 4% with buyer's assumption. |
| Annual OpEx escalation (input) | % / yr | 2.0% (illustrative) | Editable in the RFQ; replaces 2% with buyer's assumption. |
| Module / inverter degradation (input) | % / yr | 0.5% (illustrative) | Industry rule-of-thumb for modules; inverter efficiency curve tracked separately. |
The modelled Year-1 OpEx input is £18,000 / yr, escalating at 2.0% / yr.
| Input class | Specific claim / line | Evidence date | URL |
|---|---|---|---|
| EXW pricing (CN OEM 350 kW) | PENDING — OEM MOQ & tier-dependent | 2026-09-22 | Confirmed at RFQ against OEM shortlist (Sungrow, Growatt, Huawei) |
| Sea freight CN → UK port | PENDING — booking-date dependent | 2026-09-22 | FIATA freight forwarder RFQ (fiata.org) |
| HS national line / duty rate | Heading 8504.40 family (static converters), 8-digit line PENDING | 2026-09-22 | UK Global Tariff lookup; cross-check EU TARIC consultation; HS basis per WCO HS Nomenclature 2022 edition |
| UK VAT on imports | Standard 20% on (CIF + duty); postponed VAT accounting available | 2026-09-22 | UK Global Tariff — VAT notice 702 on imports (lookup page; HMRC notice cross-referenced) |
| G99 grid code (UK) | Required for installations >16 A per phase; G99 issue 1 amendment 9 (2024) | 2026-09-22 | ENA — Engineering Recommendation G99 (ENA publisher portal) |
| IEC 62109-1:2010 safety | General safety standard for PV power converters | 2026-09-22 | IEC Webstore — IEC 62109-1:2010 catalogue entry |
| IEC 62109-2:2011 safety | Particular requirements for inverters | 2026-09-22 | IEC Webstore — IEC 62109-2:2011 catalogue entry |
| UKCA marking framework | UK product conformity marking regime | 2026-09-22 | GOV.UK — UKCA marking guidance |
| SEG export rate (model input £0.075/kWh Year-1) | Provider-dependent, Ofgem band typically £0.05–£0.10/kWh | 2026-09-22 | Ofgem — Smart Export Guarantee (SEG) |
| Year-1 imported electricity tariff £0.30/kWh | Model assumption (bounded default) — bind to Ofgem retail market indicators at RFQ | 2026-09-22 | UK Ofgem retail market indicators |
| Year-1 generation yield (PVGIS reference) | ~900 kWh/kWp/yr (UK latitude, flat-roof SARAH2 baseline) | 2026-09-22 | EU PVGIS photovoltaic calculator (SARAH2) |
| UK C&I EPC cost-per-kW benchmark | Reference band for CapEx sanity check | 2026-09-22 | UK DESNZ solar PV cost data |
| Incoterms 2020 (EXW/FOB/CIF/DAP/DDP) | Official rules page | 2026-09-22 | ICC Incoterms 2020 (official rules page) |
| Metric | Value |
|---|---|
| Currency | GBP |
| Horizon (years) | 25 |
| Discount rate | 8.00 % |
| Total undiscounted cost (GBP) | 1,626,545.40 |
| Total discounted cost / PV of costs (GBP) | 1,278,132.64 |
| Total undiscounted benefit (GBP) | 3,414,016.01 |
| Total discounted benefit (GBP) | 1,276,640.63 |
| NPV (GBP) | -1,492.01 |
| IRR | 0.0799 |
| Simple payback (year) | 12.09 |
| Discounted payback (year) | — |
| LCOE (GBP/kWh) | 0.3299 |
| Year | Cost (GBP) | Benefit (GBP) | Net (GBP) | Discount factor | Discounted net (GBP) | Energy (kWh) |
|---|---|---|---|---|---|---|
| 0 | 1,050,000.00 | 0.0000 | -1,050,000.00 | 1.00 | -1,050,000.00 | 0.0000 |
| 1 | 18,000.00 | 87,885.00 | 69,885.00 | 0.9259 | 64,708.33 | 378,000.00 |
| 2 | 18,360.00 | 90,943.40 | 72,583.40 | 0.8573 | 62,228.56 | 376,110.00 |
| 3 | 18,727.20 | 94,108.23 | 75,381.03 | 0.7938 | 59,839.89 | 374,229.45 |
| 4 | 19,101.74 | 97,383.19 | 78,281.45 | 0.7350 | 57,539.20 | 372,358.30 |
| 5 | 19,483.78 | 100,772.13 | 81,288.35 | 0.6806 | 55,323.49 | 370,496.51 |
| 6 | 19,873.45 | 104,279.00 | 84,405.55 | 0.6302 | 53,189.81 | 368,644.03 |
| 7 | 20,270.92 | 107,907.91 | 87,636.99 | 0.5835 | 51,135.34 | 366,800.81 |
| 8 | 20,676.34 | 111,663.10 | 90,986.76 | 0.5403 | 49,157.32 | 364,966.80 |
| 9 | 21,089.87 | 115,548.98 | 94,459.11 | 0.5002 | 47,253.07 | 363,141.97 |
| 10 | 21,511.67 | 119,570.08 | 98,058.42 | 0.4632 | 45,420.02 | 361,326.26 |
| 11 | 21,941.90 | 123,731.12 | 101,789.22 | 0.4289 | 43,655.65 | 359,519.63 |
| 12 | 22,380.74 | 128,036.97 | 105,656.23 | 0.3971 | 41,957.54 | 357,722.03 |
| 13 | 22,828.35 | 132,492.65 | 109,664.30 | 0.3677 | 40,323.34 | 355,933.42 |
| 14 | 23,284.92 | 137,103.40 | 113,818.48 | 0.3405 | 38,750.76 | 354,153.75 |
| 15 | 23,750.62 | 141,874.60 | 118,123.98 | 0.3152 | 37,237.60 | 352,382.99 |
| 16 | 24,225.63 | 146,811.83 | 122,586.20 | 0.2919 | 35,781.74 | 350,621.07 |
| 17 | 24,710.14 | 151,920.88 | 127,210.74 | 0.2703 | 34,381.11 | 348,867.96 |
| 18 | 25,204.35 | 157,207.73 | 132,003.38 | 0.2502 | 33,033.72 | 347,123.63 |
| 19 | 25,708.43 | 162,678.56 | 136,970.13 | 0.2317 | 31,737.63 | 345,388.01 |
| 20 | 26,222.60 | 168,339.77 | 142,117.17 | 0.2145 | 30,490.98 | 343,661.07 |
| 21 | 26,747.05 | 174,198.00 | 147,450.94 | 0.1987 | 29,291.98 | 341,942.76 |
| 22 | 27,281.99 | 180,260.09 | 152,978.09 | 0.1839 | 28,138.87 | 340,233.05 |
| 23 | 27,827.63 | 186,533.14 | 158,705.50 | 0.1703 | 27,029.97 | 338,531.88 |
| 24 | 28,384.19 | 193,024.49 | 164,640.31 | 0.1577 | 25,963.67 | 336,839.22 |
| 25 | 28,951.87 | 199,741.74 | 170,789.87 | 0.1460 | 24,938.38 | 335,155.03 |
Read of the cashflow table: Year-1 benefit is £87,885 (= 378,000 kWh × (0.7 × £0.30 + 0.3 × £0.075)); Year-1 net is +£69,885 after £18,000 OpEx; cumulative nominal net crosses zero in year 12; cumulative discounted net never crosses zero inside the 25-year horizon at 8% WACC — hence the NPV of −£1,492 and the "no discounted payback" line.
| Input | Value used by the scenario model | Classification |
|---|---|---|
| Horizon | 25 years | Model assumption (buyer-editable on RFQ) |
| Discount rate (WACC) | 8.00% / yr | Model assumption (buyer-editable on RFQ) |
| PV system size (DC) | 420 kWp | Model assumption |
| Specific yield | 900 kWh / kWp / yr → 378,000 kWh Year-1 generation | Model assumption |
| Self-consumption share | 70% (30% exported on SEG) | Model assumption |
| Year-1 imported electricity tariff | £0.30 / kWh | Model assumption |
| Year-1 SEG export tariff | £0.075 / kWh | Model assumption |
| Annual electricity-price escalation | 4.0% / yr | Model assumption |
| Annual module / inverter degradation | 0.5% / yr | Model assumption |
| Year-0 CapEx | £1,050,000 | Model assumption (illustrative band) |
| Year-1 OpEx | £18,000 / yr | Model assumption |
| OpEx escalation | 2.0% / yr | Model assumption |
| Residual value (amount) | £0 | Model assumption (bounded default — explicit) |
| Residual value (year) | End of year 25 | Model assumption (bounded default — explicit) |
| Financing / tax relief | Not modelled (all-cash, pre-tax) | Model assumption — out of scope |
| Certificate / Standard | Status on this page | Issuing body / standard reference | Deep-link | Notes |
|---|---|---|---|---|
| UKCA marking (UK product conformity) | PENDING — confirm on datasheet | UK gov.uk UKCA framework | GOV.UK — UKCA marking guidance | Applies once CE recognition transition ends for the relevant legislation. |
| IEC 62109-1:2010 (PV power converter safety — general) | PENDING — confirm on datasheet | IEC, edition 2.0 (2010), via accredited test lab | IEC Webstore — IEC 62109-1:2010 catalogue entry | Test report number must be provided by the OEM. Cite IEC 62109-1:2010 edition verbatim. |
| IEC 62109-2:2011 (PV power converter safety — particular for inverters) | PENDING — confirm on datasheet | IEC, edition 1.0 (2011), via accredited test lab | IEC Webstore — IEC 62109-2:2011 catalogue entry | Test report number must be provided by the OEM. Cite IEC 62109-2:2011 edition verbatim. |
| ENA Engineering Recommendation G99 (issue 1 amendment 9, 2024) | PENDING — confirm on datasheet | Energy Networks Association (ENA) | ENA — Engineering Recommendation G99 (issue 1 amendment 9, 2024) | Required for any inverter >16 A per phase; DNO-specific interface settings apply. |
| EMC (EN 61000-6-2 / -6-4 family) | PENDING — confirm on datasheet | Notified / accredited test lab | European Commission — EMC Directive (2014/30/EU) harmonised standards list | Test report to be supplied with RFQ. |
| MCS-equivalent install standard | Optional for SEG | MCS (UK) | MCS — Standards index (MCS 001, MCS 005, MCS 012) | MCS certification is for the install / module / inverter set per MCS standards; SEG eligibility depends on the licensed supplier's terms. |
No certificate numbers, supplier logos or rankings are claimed on this page. The OEM must supply the certificate number and the issuing body's name for each line above before any shipment is dispatched.
| Line | Status |
|---|---|
| HS national line (8-digit GTUK code) — static power converters for solar PV typically under heading 8504.40; the precise UK national line must be confirmed on the UK Global Tariff lookup against the OEM datasheet and the confirmed HS national line before any rate is applied. Cross-reference EU TARIC consultation for transit lanes. | PENDING |
| UK import duty (MFN applied duty at the 8-digit line) | PENDING — lookup at UK Global Tariff lookup |
| UK VAT on imports (standard rate 20% applied to CIF + duty; postponed VAT accounting available) | PENDING — confirm via GOV.UK — VAT notice 702 on imports |
| Customs clearance + broker fee | PENDING — per-shipment quote |
| UK inland haulage (port → rooftop site, oversize) | PENDING — per-shipment quote |
All percentage and monetary lines in this section remain PENDING until the confirmed HS national line is locked against the OEM datasheet. The scenario TCO model in §4 does not depend on the duty rate — CapEx is an input, not a computed output.
The computed result sits within £1,500 of break-even at 8% WACC. Three single-variable moves dominate the verdict:
Submit the RFQ with the buyer's actual CapEx quote, contracted kWh tariff, and load profile to re-run the scenario model against binding inputs.