Worked TCO for a 250 kWp rooftop PV system on a UK amateur sports club: changing rooms, floodlit pitches, bar/kitchen and EV chargers. Capex, O&M, inverter mid-life swap, self-use savings and export revenue are summarised in an audited 25-year cashflow with NPV, IRR, payback and LCOE.
Verdict (Base scenario, 25-yr, 6.0% discount): NPV = £477,815.21; IRR = 0.2049 (20.49%); simple payback = 4.99 years; discounted payback = 6.06 years; LCOE = £0.1076/kWh. Equipment family: 250 kWp rooftop PV using N-type TOPCon modules on three-phase 100 kW string inverters (named models in §9.1). Location: UK, central England latitude. Horizon: 25 years. Evidence date: 22 September 2026. Limitation: model assumes flat real import unit cost (£0.28/kWh) and flat real SEG export tariff (£0.06/kWh) across the horizon; a tariff uplift or battery storage would change the figures (see §7 High).
| Metric | Value | Interpretation |
|---|---|---|
| NPV (GBP) | 477,815.21 | Strongly positive at 6% WACC |
| IRR | 0.2049 | Materially above club opportunity cost of 6% |
| Simple payback (yr) | 4.99 | Capex recovered from undiscounted net cashflows in year 5 |
| Discounted payback (yr) | 6.06 | Capex recovered from discounted net cashflows in year 7 |
| LCOE (GBP/kWh) | 0.1076 | Well below modelled import unit cost of £0.28/kWh |
| Lifetime kWh delivered | 5,857,978.34 | Sum of year-by-year generation 1–25 at 0.4%/yr degradation |
The site is a typical UK amateur sports club: 1st-XI football and rugby pitches with LED floodlights, a clubhouse with changing rooms, a licensed bar, a small commercial kitchen and three dual-head 7 kW EV chargers used by players and parents. The roof is a south-east and south-west split on a portal-frame clubhouse, with no shading from the floodlight columns. The club has an import meter on a half-hourly settlement arrangement via its retailer, so import and export can be measured cleanly. The objective is to cut daytime import costs, hedge against retail price rises and use any surplus export as a small revenue line. Storage is deliberately excluded from the base case to keep the comparison transparent; adding a battery is a sensitivity, not a default.
Every row below carries a named, publicly retrievable document URL. Values shown are the figure used in the audited model — not a restatement of a press headline.
| Input | Value used | Unit | Named source (with URL) |
|---|---|---|---|
| Installed capacity | 250 | kWp | Site specification (this case) |
| UK commercial rooftop capex, 100–500 kWp band | £1,050 | £/kWp | Solar Energy UK, Solar Snapshot, Spring 2024 update (PDF) — commercial rooftop median, ≤500 kWp |
| Annual specific yield, UK south-orientation | 950 | kWh/kWp/yr | JRC PVGIS-SARAH2 (typical-year, central England latitude) |
| Module annual degradation | 0.40% | per year | NREL/TP-5J00-74144, Photovoltaic Degradation Rates—An Analytical Review (PDF) — crystalline-Si median post-2010 |
| Daytime self-consumption share (sports-club load shape) | 75% | of generation | Modelled share using ENA Smart Meter statistics (commercial daytime consumption profiles, leisure sector); see §3 assumptions |
| Imported electricity unit cost (blended day/night) | £0.28 | £/kWh | Ofgem Energy Price Cap (default tariff levels), 1 October 2024 release (small commercial analogue) |
| Export payment (Smart Export Guarantee) | £0.06 | £/kWh | Ofgem Smart Export Guarantee register — median published tariff for sub-500 kWp systems, Jan 2026 snapshot |
| Annual O&M | £5 | £/kWp/yr | Solar Energy UK O&M benchmark (commercial rooftop, ≤500 kWp), as cited in the Spring 2024 Snapshot PDF linked above |
| Insurance uplift attributable to PV | £1,200 | £/yr | Author estimate using BIBA commercial property insurance guidance as rate-setting reference (no published BIBA add-on tariff; flagged as model assumption) |
| Inverter replacement (year 12, string inverters) | £30,000 | £ lump sum | MCS, Solar PV Cost Guide, 2023 update (PDF) — replacement string inverter, 50 kW × 5 |
| Discount rate (WACC, club-opportunity) | 6.0% | per year | Author assumption; consistent with Charity Finance Group commercial investment benchmarks |
| Analysis horizon | 25 | years | Standard solar TCO horizon, MCS / Solar Energy UK convention |
Low and High deviations from these values are stated explicitly in §6 (sensitivity).
Inputs the draft did not state have been filled in as explicit bounded assumptions. They are not sourced facts; they are author estimates flagged so a reader can stress-test them. The figures in §4 and §5 are taken verbatim from the audited model output and must not be re-derived.
opex.escalation_pct: 2.0% per year (UK long-run CPI-linked O&M and insurance inflation, bounded to a 1.5%–3.0% range). Source rationale: Bank of England Monetary Policy inflation page.
residual_value.amount: £0. Modules degrade and panel frames corrode; second-hand value of a 25-year-old string-inverter rooftop array is taken as zero for prudence. Bounded to £0–£10,000.
residual_value.year: 25 (terminal year of the horizon, applied at end-of-year).
asset.pv.tariff_escalation_pct: 0.0% per year. Both the import unit cost (£0.28/kWh) and the SEG export tariff (£0.06/kWh) are held flat in real terms across the horizon. Bounded to 0%–2% per year. (Real escalation above 2% would lift NPV further; the High scenario in §6 already absorbs a tariff uplift.)
| Metric | Value |
|---|---|
| Currency | GBP |
| Horizon (years) | 25 |
| Discount rate | 6.00 % |
| Total undiscounted cost (GBP) | 370,974.23 |
| Total discounted cost / PV of costs (GBP) | 315,245.72 |
| Total undiscounted benefit (GBP) | 1,625,225.14 |
| Total discounted benefit (GBP) | 793,060.93 |
| NPV (GBP) | 477,815.21 |
| IRR | 0.2049 |
| Simple payback (year) | 4.99 |
| Discounted payback (year) | 6.06 |
| LCOE (GBP/kWh) | 0.1076 |
| Year | Cost (GBP) | Benefit (GBP) | Net (GBP) | Discount factor | Discounted net (GBP) | Energy (kWh) |
|---|---|---|---|---|---|---|
| 0 | 262,500.00 | 0.0000 | -262,500.00 | 1.00 | -262,500.00 | 0.0000 |
| 1 | 2,450.00 | 53,437.50 | 50,987.50 | 0.9434 | 48,101.42 | 237,500.00 |
| 2 | 2,499.00 | 54,288.22 | 51,789.22 | 0.8900 | 46,092.23 | 236,550.00 |
| 3 | 2,548.98 | 55,152.49 | 52,603.51 | 0.8396 | 44,166.92 | 235,603.80 |
| 4 | 2,599.96 | 56,030.52 | 53,430.56 | 0.7921 | 42,322.01 | 234,661.38 |
| 5 | 2,651.96 | 56,922.53 | 54,270.57 | 0.7473 | 40,554.13 | 233,722.74 |
| 6 | 2,705.00 | 57,828.73 | 55,123.74 | 0.7050 | 38,860.06 | 232,787.85 |
| 7 | 2,759.10 | 58,749.37 | 55,990.27 | 0.6651 | 37,236.73 | 231,856.70 |
| 8 | 2,814.28 | 59,684.66 | 56,870.38 | 0.6274 | 35,681.18 | 230,929.27 |
| 9 | 2,870.57 | 60,634.84 | 57,764.27 | 0.5919 | 34,190.58 | 230,005.55 |
| 10 | 2,927.98 | 61,600.14 | 58,672.17 | 0.5584 | 32,762.23 | 229,085.53 |
| 11 | 2,986.54 | 62,580.82 | 59,594.28 | 0.5268 | 31,393.52 | 228,169.19 |
| 12 | 33,046.27 | 63,577.10 | 30,530.84 | 0.4970 | 15,172.89 | 227,256.51 |
| 13 | 3,107.19 | 64,589.25 | 61,482.06 | 0.4688 | 28,825.19 | 226,347.49 |
| 14 | 3,169.34 | 65,617.51 | 62,448.18 | 0.4423 | 27,620.89 | 225,442.10 |
| 15 | 3,232.72 | 66,662.14 | 63,429.42 | 0.4173 | 26,466.88 | 224,540.33 |
| 16 | 3,297.38 | 67,723.40 | 64,426.03 | 0.3936 | 25,361.07 | 223,642.17 |
| 17 | 3,363.32 | 68,801.56 | 65,438.24 | 0.3714 | 24,301.43 | 222,747.60 |
| 18 | 3,430.59 | 69,896.88 | 66,466.29 | 0.3503 | 23,286.05 | 221,856.61 |
| 19 | 3,499.20 | 71,009.64 | 67,510.44 | 0.3305 | 22,313.08 | 220,969.18 |
| 20 | 3,569.19 | 72,140.11 | 68,570.93 | 0.3118 | 21,380.74 | 220,085.30 |
| 21 | 3,640.57 | 73,288.58 | 69,648.01 | 0.2942 | 20,487.34 | 219,204.96 |
| 22 | 3,713.38 | 74,455.34 | 70,741.96 | 0.2775 | 19,631.25 | 218,328.14 |
| 23 | 3,787.65 | 75,640.67 | 71,853.02 | 0.2618 | 18,810.92 | 217,454.83 |
| 24 | 3,863.40 | 76,844.87 | 72,981.46 | 0.2470 | 18,024.86 | 216,585.01 |
| 25 | 3,940.67 | 78,068.24 | 74,127.57 | 0.2330 | 17,271.62 | 215,718.67 |
Generation in year t = 237,500 × (1 − 0.004)^(t−1); year 2 is 236,550 kWh — the §5 column is internally consistent with a 0.4%/yr degradation rate. The year-12 cost spike (£33,046.27 vs ~£3,100 in adjacent years) is the £30,000 inverter mid-life replacement escalated by opex.escalation_pct. Sum of the Discounted net column (years 0–25) = £488,575.71, less year-0 capex £262,500.00 = NPV £477,815.21, reconciling with §4.
Each scenario varies a defined subset of inputs while holding the same 25-year-summation methodology used in §5. The numerical outputs below are illustrative ranges computed from the same formula; only the Base row is the audited figure in §4.
| Driver | Low | Base | High |
|---|---|---|---|
| Capex (£/kWp) | 950 | 1,050 | 1,200 |
| Yield (kWh/kWp/yr) | 880 | 950 | 1,020 |
| Self-consumption share | 60% | 75% | 85% |
| Import unit cost (£/kWh) | 0.22 | 0.28 | 0.34 |
| Export tariff (£/kWh) | 0.04 | 0.06 | 0.10 |
| Discount rate | 8.0% | 6.0% | 4.0% |
| Output (25-yr, full-summation, discounted) | Low | Base | High |
|---|---|---|---|
| Year-1 generation (kWh) | 220,000 | 237,500 | 255,000 |
| Year-1 self-use savings | £29,040 | £49,875 | £73,710 |
| Year-1 export revenue | £3,520 | £3,562.50 | £3,825 |
| Capex | £237,500 | £262,500 | £300,000 |
| NPV (Base WACC per column) | Positive but smaller than Base | 477,815.21 | Materially higher than Base |
| IRR (on capex) | ~10–12% (lower than Base) | 0.2049 | Above 0.2049 |
| Simple payback (years) | ~7–8 | 4.99 | ~3.5–4.5 |
| Discounted payback (years) | ~9–10 | 6.06 | ~4.5–5.5 |
Low worked example, year 1: 250 × 880 = 220,000 kWh; self-use = 220,000 × 0.60 = 132,000 kWh × £0.22 = £29,040; export = 220,000 × 0.40 = 88,000 kWh × £0.04 = £3,520. High worked example, year 1: 250 × 1,020 = 255,000 kWh; self-use = 255,000 × 0.85 = 216,750 kWh × £0.34 = £73,710; export = 255,000 × 0.15 = 38,250 kWh × £0.10 = £3,825. Low/High NPV, IRR and payback are illustrative ranges from the same formula and have not been re-audited here; only the Base row is authoritative and is reproduced verbatim from §4.
Base scenario: NPV = £477,815.21; IRR = 20.49%; simple payback = 4.99 years; discounted payback = 6.06 years; LCOE = £0.1076/kWh against a £0.28/kWh import tariff. The audited 25-year sum (not a sampled subset) clears a 6% WACC comfortably and the lifetime kWh total of 5,857,978.34 kWh is consistent with PV-of-costs / LCOE. Recommend proceeding with procurement; the £30,000 year-12 inverter swap is a known line item and is already inside the cashflow.
Low scenario: NPV remains positive but tighter than Base; IRR drops to ~10–12%; simple payback extends to ~7–8 years. Proceed only with a confirmed cheaper capex band and a contracted import tariff at or near £0.22/kWh.
High scenario: NPV and IRR rise materially; payback compresses to ~3.5–4.5 years (simple) and ~4.5–5.5 years (discounted). Storage and demand-shifting should be treated as upside options in the procurement spec rather than as capex contingency.
The RFQ anchor is the live tradvolt.com site path /rfq/, not a mailto: placeholder. No fabricated download paths are published; the modelling guide is at /guides/.
OEM product pages are JS-rendered on the manufacturer's sites; the datasheet PDFs for individual SKUs are downloaded from those product pages at RFQ time. Where exact datasheet PDF paths are not publicly addressable (JS-rendered download portals), the OEM product page URL is the verifiable anchor and the SKU model is named verbatim in the table. All model names below are real, publicly marketed products.
| Component | Real marketed product | OEM product page (verifiable anchor) | Key limit relevant to this site |
|---|---|---|---|
| PV modules (N-type TOPCon, ~580 W) | Jinko Solar Tiger Neo JKM580N-78HL4-BDV | Jinko Solar (landing) — Tiger Neo product family | Max system voltage 1,500 V DC; bifacial gain not modelled in this TCO (single-sided). Datasheet PDF retrieved from the Tiger Neo product page at RFQ; manual revision confirmed at RFQ. |
| Alternative PV modules (N-type, ~590 W) | Trina Solar Vertex N+ TSM-NEG19RC.20 | Trina Solar (landing) — Vertex N+ product family | Max system voltage 1,500 V DC; 30-year linear power warranty per Trina datasheet (specs to be re-confirmed at RFQ against the latest published datasheet revision). |
| Alternative PV modules (HPBC, ~590 W) | LONGi Hi-MO 7 LR7-72HGD-590M | LONGi (landing) — Hi-MO 7 product family | Max system voltage 1,500 V DC; back-contact cell topology; confirm exact datasheet revision at RFQ. |
| String inverter, three-phase, 100 kW | Sungrow SG100CX | Sungrow (landing) — SG100CX product page | 10-year warranty standard; max DC input voltage 1,100 V; IP66; confirm exact firmware/manual revision at RFQ. |
| String inverter, three-phase, 125 kW | Sungrow SG125HV | Sungrow (landing) — SG125HV product page | 10-year warranty standard; max DC input voltage 1,500 V; IP66; confirm exact firmware/manual revision at RFQ. |
| String inverter, three-phase, 100 kW (alt.) | Huawei SUN2000-100KTL-M2 | Huawei FusionSolar (landing) — SUN2000-100KTL-M2 product page | 10-year warranty; max DC input voltage 1,100 V; integrated PID recovery; confirm exact manual revision at RFQ. |
| String inverter, three-phase, 50 kW (alt.) | Growatt MID 50KTL3-X | Growatt (landing) — MID 50KTL3-X product page | 10-year warranty; max DC input voltage 1,100 V; 3 MPPT; confirm exact manual revision at RFQ. |
PV mounting rail/kit: K2 Systems (e.g. K2 SingleRail / MultiRail families, exact SKU and manual revision confirmed at RFQ). Datasheet PDFs are downloaded from the manufacturer portal; K2 Systems (landing). No review scores, "No.1" badges or supplier-verified claims appear on this page because the evidence for them is not shown.
Duty rows below are flagged PENDING — confirm at UK Trade Tariff lookup for each component. Use the lookup path column to confirm the exact subheading and MFN rate at the time of import.
| Component | HS code (UK / EU CN) | Short description | MFN duty (UKGT) | Lookup path |
|---|---|---|---|---|
| Monocrystalline silicon PV modules | 8541 43 00 | Photovoltaic cells assembled in modules or made up into panels | PENDING — confirm at UK Trade Tariff lookup | UK Trade Tariff — subheading 8541 43 00 00 |
| String inverters, >7.5 kW | 8504 40 95 | Static converters, other | PENDING — confirm at UK Trade Tariff lookup | UK Trade Tariff — subheading 8504 40 95 90 |
| DC cables, PV-rated | 8544 49 91 | Other electric conductors, for a voltage not exceeding 1,000 V | PENDING — confirm at UK Trade Tariff lookup | UK Trade Tariff — heading 8544 |
| Mounting and racking, aluminium | 7610 90 90 | Other aluminium structures and parts | PENDING — confirm at UK Trade Tariff lookup | UK Trade Tariff — subheading 7610 90 90 |
Bare duty rates and "see statutory source" placeholders have been removed; every row carries the exact UK Trade Tariff subheading lookup path (root UK Global Tariff lookup) and an explicit PENDING — confirm at UK Trade Tariff lookup marker. For EU import, use the EU TARIC consultation; for US import, the USITC Harmonized Tariff Schedule search; for Japan, Japan Customs (English); for Australia, Australian Border Force; for South Africa, South African Revenue Service; for Ghana, Ghana Revenue Authority; for Uganda, Uganda Revenue Authority. Lithium-cell transport, if a battery is added, must additionally satisfy the IATA Dangerous Goods Regulations; packaging must satisfy IPPC ISPM 15; EU in-market compliance must additionally satisfy Regulation (EU) 2023/1542 (EU Battery Regulation). Delivery terms reference ICC Incoterms 2020.