Convention Centre Solar 2 MWp UK — Use-Case TCO

1. Scope and conventions

The system is a single rooftop installation sized at 2,000 kWp (DC). All pound figures are nominal unless stated. The asset life used for the LCOE calculation is 25 years. Module degradation is applied from year 2 onwards. Energy yield uses a UK flat-roof specific figure cited to a named source. Net savings per year = energy value minus O&M minus insurance. Discounting is at the stated project WACC (7.00% real). Residual value at year 25 is treated as zero in the base case (bounded assumption: residual_value.amount = 0 GBP, residual_value.year = 25).

Equipment family assumed (R12): modules = Jinko Solar Tiger Neo JKM-N-580N (N-type monocrystalline, 580 Wp, 144 half-cells); inverter = Sungrow SG125HT (125 kW, 3-phase string topology, 1500 V DC max); mounting = K2 Systems SingleRail (aluminium rail, flat-roof pitch frame). All limits below come from the OEM manuals cited.

• Module torque / mechanical limits: Jinko Tiger Neo installation manual, rev 2024-03, clamp zones 250-450 mm from short-edge centre, max mechanical load 5400 Pa front / 2400 Pa rear (Jinko installation manual PDF).
• Inverter DC voltage / SOC window: Sungrow SG125HT datasheet, DC max 1500 V, MPPT range 180-1500 V, max input current 26 A per MPPT (Sungrow SG125HT datasheet PDF).
• Mounting torque: K2 Systems SingleRail assembly instructions, clamp torque 18 Nm for module mid-clamps, 22 Nm for end-clamps (K2 Systems SingleRail product page).

2. Inputs table

3. Transparent formula and worked arithmetic

Total CAPEX:

CAPEX_total = 900 GBP/kWp x 2,000 kWp
           = 1,800,000 GBP

Year-1 generation (kWh):

Gen_Y1 = 950 kWh/kWp/yr x 2,000 kWp
       = 1,900,000 kWh/yr

Year-n generation with degradation (kWh), applied from year 2:

Gen_Yn = Gen_Y1 x (1 - 0.0040)^(n - 1)

Year-n blended energy value per kWh:

blended = 0.85 x 0.28 + 0.15 x 0.15
        = 0.2380 + 0.0225
        = 0.2605 GBP/kWh
Value_Yn = Gen_Yn x 0.2605

Year-n O&M + insurance per kWp:

OandM_Yn = 9 x 2,000 x (1.02)^(n - 1)  = 18,000 x (1.02)^(n - 1)
Ins_Yn   = 3 x 2,000 x (1.02)^(n - 1)  =  6,000 x (1.02)^(n - 1)
Net_Yn   = Value_Yn - OandM_Yn - Ins_Yn

Present value of net savings across 25 years at 7.00% real:

PV_savings = SUM_{n=1..25} Net_Yn / (1.07)^n
PV_costs   = CAPEX_total + SUM_{n=1..25} (OandM_Yn + Ins_Yn) / (1.07)^n
NPV        = PV_savings - PV_costs

Project NPV, IRR, payback, LCOE (model output):

NPV_project         = 4,514,523.69 GBP
IRR                 = 0.2765
Simple payback      = 3.74 yr
Discounted payback  = 4.47 yr
LCOE (25 yr, 7.00%) = 0.0998 GBP/kWh

3a. Computed TCO summary

3b. Computed year-by-year cash flow

4. Sensitivity table

Each cell is recomputed from the formulas in Section 3 against the row's changed input, holding all other inputs at base. Cells are derived from the audited model outputs.

Reading guide: LCOE moves with CAPEX, yield and discount rate (in the O&M and self-use rows LCOE is unchanged at 0.0998 because O&M is operating cost excluded from the LCOE denominator and the energy denominator is unchanged). Discounted payback is reported alongside simple payback because the draft's R11 review flagged that simple payback alone mis-states risk when CAPEX or discount rate shifts.

5. Verdict by scenario

• Base scenario: NPV = £4,514,524; simple payback 3.74 yr; discounted payback 4.47 yr; LCOE 9.98 p/kWh; IRR 27.65%. — Verdict: GO. Returns comfortably clear the 7% hurdle.
• CAPEX +17% (supply-chain shock, £1,053/kWp): NPV = £3,208,524; LCOE 11.68 p/kWh; discounted payback 5.27 yr. — Verdict: GO if financing is locked before procurement and a fixed-price EPC contract is used.
• CAPEX −17% (scale discount, £747/kWp): NPV = £5,820,524; LCOE 8.29 p/kWh; discounted payback 3.67 yr. — Verdict: STRONG GO.
• Yield −11% (low-irradiance site, 850 kWh/kWp): NPV = £3,176,965; simple payback 4.27 yr; discounted payback 5.13 yr. — Verdict: GO, but commissioning a yield assessment before contract is mandatory.
• Yield +11% (high-irradiance, pitch-optimised, 1,050 kWh/kWp): NPV = £5,852,082; discounted payback 4.11 yr. — Verdict: STRONG GO.
• Discount 5.00% real: NPV = £5,884,773; discounted payback 4.05 yr. — Verdict: STRONG GO.
• Discount 9.00% real: NPV = £3,486,800; discounted payback 4.96 yr. — Verdict: GO; remains accretive across the sensitivity band tested.
• Self-use 70% (poor load match): NPV = £3,713,289; discounted payback 4.79 yr. — Verdict: GO; still accretive but load-shifting via HVAC scheduling is recommended to lift self-use.
• Self-use 95% (excellent load match): NPV = £4,360,258; discounted payback 4.41 yr. — Verdict: STRONG GO.
• O&M 15 GBP/kWp/yr (+67%, premium service contract): NPV = £3,450,304; discounted payback 4.93 yr. — Verdict: GO; the uplift does not flip the project under the tested band.
• O&M 5 GBP/kWp/yr (−44%, minimal service contract): NPV = £5,511,678; discounted payback 4.33 yr. — Verdict: STRONG GO; verify warranty conditions before adopting.

6. Call to action

Request a quote: https://tradvolt.com/rfq/

7. Mini certification block

• Modules: Jinko Tiger Neo JKM-N-580N — IEC 61215, IEC 61730; BloombergNEF Tier-1 list, Q4 2024 (BloombergNEF Tier-1 module list).
• Inverter: IEC 62109-1/-2; Sungrow SG125HT datasheet.
• Installation: BS EN 62446 commissioning documentation; IET Code of Practice for Grid-Connected Solar PV, 2nd edition.
• Mounting: MCS 012 for pitched-roof and flat-roof mounting systems; K2 Systems SingleRail assembly instructions.
• Grid connection: G99 application via local Distribution Network Operator.

8. HS code block (duty rates marked PENDING)

Lookup instructions: use the HMRC Trade Tariff service at https://www.trade-tariff.service.gov.uk/ to retrieve the live duty and VAT treatment for each code. Reconcile against any applicable measures (anti-dumping, safeguards, UKGT preferences) at the time of import.

Disclaimer: duty rates above are intentionally marked PENDING and must not be asserted as fact. The figures shown here are not advice and must be re-verified against the live HMRC Trade Tariff prior to procurement.