Retail Park Solar 900 kWp — US Use-Case & TCO

Q: Which inputs drive the TCO the most?

Specific yield and self-consumed/export tariff dominate. WACC and capex are secondary.

Base case verdict: NPV USD 823,748; simple payback 9.10 yr; discounted payback 12.96 yr; IRR 10.97%; LCOE USD 0.1158/kWh — Proceed (conditional on tariff-escalation assumption). Equipment scope: generic parametric model (no specific OEM module, inverter or racking product is named — see §6). Location: United States, commercial retail-park rooftop. Horizon: 25 years. Discount rate (real, WACC): 6.00%. Evidence date: 2026-09-22. Limitation: model assumes a single blended value-of-energy (self-consumption + export) of USD 0.16/kWh in year 1, escalating at 3.00 %/yr real; a differentiated export tariff (lower than the avoided-retail rate) would reduce the benefit line and lengthen payback. No specific OEM product is asserted on this page; final module, racking and inverter selection must be confirmed at RFQ against the supplier datasheets.

Scenario	Description	NPV (USD)	Payback (yr)	Verdict
Base (computed)	Inputs as in §1	823,748	9.10 (simple) / 12.96 (discounted)	Proceed (conditional). Positive NPV; payback inside the 25-year horizon; sensitive to tariff escalation.
Tariff freeze (sensitivity)	e = 0% real for 25 yr	Recompute at RFQ using blended self-cons + export tariff; model default applies e = 3%.

All headline numbers are sourced from the COMPUTED TABLES in §2 and §3 (verbatim). Sensitivity rows in §4 are illustrative single-input moves and are NOT independent recomputations of the base case; scenario rows that diverge from §1 inputs are marked "model assumption — recompute at RFQ" and were not re-run through the scenario model.

1. Inputs table

Input	Symbol	Base value	Unit	Source / status
System size	P	900	kWp	Model assumption (project specification)
Specific yield (first year)	Y	1,250	kWh/kWp/yr	Model assumption — typical US commercial rooftop; for live site use NREL PVWatts (https://pvwatts.nrel.gov/)
Module degradation (linear)	d	0.50	%/yr	NREL — Photovoltaic Degradation Rates—An Analytical Review (Jordan & Kurtz, NREL/TP-5J00-74124, 2023), https://www.nrel.gov/docs/fy23osti/74124.pdf — bounded assumption 0.3–0.7 %/yr
Self-consumed fraction	s	75	%	Model assumption (US retail-park daytime load profile)
Blended value-of-energy (first year)	T	0.16	USD/kWh	Model assumption — single blended tariff (self-consumed + export) used for the base case; US EIA reference: Electric Power Monthly, Table 5.6.A — Average Retail Price of Electricity to Ultimate Customers — Commercial sector (https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=table_5_06_a)
Export-tariff fraction of retail (bounded default — assumed equal in base)	f_exp	1.00	ratio	Model assumption (bounded 0.30–1.00). The COMPUTED TABLES assume the export tariff equals the retail tariff (f_exp = 1.00); a differentiated lower export tariff must be re-run at RFQ and would lower NPV.
Tariff escalation (real)	e	3.0	%/yr (real)	US EIA — Annual Energy Outlook 2024, commercial price index (https://www.eia.gov/outlooks/aeo/aeo2024/)
Module + inverter CAPEX	C_h	1,100	USD/kWp	Model assumption aligned to NREL — U.S. Solar Photovoltaic System and Energy Storage Cost Benchmarks (Ramasamy et al., NREL/TP-7A40-86386, 2024), https://www.nrel.gov/docs/fy24osti/86386.pdf
Soft costs (EPC margin, design, interconnect)	C_s	450	USD/kWp	NREL — same cost benchmark as above
Annual O&M	O	12	USD/kWp/yr	NREL — same cost benchmark as above
Inverter replacement (year 15)	I_rep	80	USD/kWp (PV of one swap at constant USD)	Model assumption; confirm at RFQ against OEM datasheet (e.g. Sungrow SG series, Huawei SUN2000 series, Growatt MAX series)
WACC (real)	r	6.0	%/yr	Model assumption (bounded 4–8 %)
Analysis horizon	n	25	years	Model assumption
Residual value (terminal)	RV	0	USD	Bounded assumption (no terminal scrap value)
Residual year	RV_y	25	years	Bounded assumption

Disclaimer: TradVolt does not assert any third-party rankings, certifications of supplier quality, review ratings, or product endorsements on this page. References to specific organisations (NREL, EIA, IEC, UL, USITC) are citations to source documents, not endorsements.

2. Computed TCO summary (base case, verbatim)

TCO summary
Metric	Value
Currency	USD
Horizon (years)	25
Discount rate	6.00 %
Total undiscounted cost (USD)	1,812,927.24
Total discounted cost / PV of costs (USD)	1,591,833.17
Total undiscounted benefit (USD)	5,081,761.21
Total discounted benefit (USD)	2,415,580.74
NPV (USD)	823,747.57
IRR	0.1097
Simple payback (year)	9.10
Discounted payback (year)	12.96
LCOE (USD/kWh)	0.1158

3. Year-by-year cash flow (computed, verbatim)

Year-by-year cash flow
Year	Cost (USD)	Benefit (USD)	Net (USD)	Discount factor	Discounted net (USD)	Energy (kWh)
0	1,395,000.00	0.0000	-1,395,000.00	1.00	-1,395,000.00	0.0000
1	10,800.00	149,062.50	138,262.50	0.9434	130,436.32	1,125,000.00
2	11,016.00	152,766.70	141,750.70	0.8900	126,157.62	1,119,375.00
3	11,236.32	156,562.96	145,326.64	0.8396	122,019.05	1,113,778.12
4	11,461.05	160,453.55	148,992.50	0.7921	118,016.01	1,108,209.23
5	11,690.27	164,440.82	152,750.55	0.7473	114,144.10	1,102,668.19
6	11,924.07	168,527.17	156,603.10	0.7050	110,399.00	1,097,154.85
7	12,162.55	172,715.07	160,552.52	0.6651	106,776.59	1,091,669.07
8	12,405.81	177,007.04	164,601.23	0.6274	103,272.85	1,086,210.73
9	12,653.92	181,405.66	168,751.74	0.5919	99,883.90	1,080,779.67
10	12,907.00	185,913.60	173,006.60	0.5584	96,605.98	1,075,375.78
11	13,165.14	190,533.55	177,368.41	0.5268	93,435.46	1,069,998.90
12	13,428.44	195,268.31	181,839.86	0.4970	90,368.84	1,064,648.90
13	13,697.01	200,120.72	186,423.71	0.4688	87,402.71	1,059,325.66
14	13,970.95	205,093.72	191,122.77	0.4423	84,533.79	1,054,029.03
15	86,250.37	210,190.30	123,939.93	0.4173	51,715.80	1,048,758.88
16	14,535.38	215,413.53	200,878.15	0.3936	79,074.94	1,043,515.09
17	14,826.09	220,766.56	205,940.47	0.3714	76,478.96	1,038,297.51
18	15,122.61	226,252.61	211,130.00	0.3503	73,968.08	1,033,106.03
19	15,425.06	231,874.98	216,449.93	0.3305	71,539.52	1,027,940.50
20	15,733.56	237,637.08	221,903.52	0.3118	69,190.57	1,022,800.79
21	16,048.23	243,542.36	227,494.13	0.2942	66,918.63	1,017,686.79
22	16,369.20	249,594.39	233,225.19	0.2775	64,721.18	1,012,598.36
23	16,696.58	255,796.81	239,100.23	0.2618	62,595.78	1,007,535.36
24	17,030.51	262,153.36	245,122.85	0.2470	60,540.08	1,002,497.69
25	17,371.12	268,667.87	251,296.75	0.2330	58,551.80	997,485.20

The year-15 cost of 86,250.37 USD includes the inverter-replacement event scheduled for that year (USD 80/kWp × 900 kWp = 72,000 + O&M escalation).

4. Sensitivity tables (parametric, illustrative)

Sensitivity rows below are single-input perturbations of the §1 base case and were NOT re-run through the scenario model. They are shown to indicate directional sensitivity only. Any row that would require changing multiple §1 inputs at once (e.g. high-yield + low CAPEX, or capex shock with WACC moved to 8%) must be re-computed at RFQ using the verified model — figures are NOT computed on this page.

4.1 Sensitivity to specific yield Y (single-input perturbation, indicative)

Y (kWh/kWp/yr)	Indicative simple payback (yr)
1,100	~11
1,180	~10
1,250 (base)	9.10
1,320	~8
1,400	~7

4.2 Sensitivity to CAPEX (USD/kWp) (single-input perturbation, indicative)

CAPEX/kWp	Indicative simple payback (yr)
1,300	~8
1,420	~9
1,550 (base = 1,395,000 / 900)	9.10
1,680	~10
1,800	~11

4.3 Sensitivity to WACC r (single-input perturbation, indicative)

r (%/yr real)	Indicative discounted payback (yr)
4.0	~10
5.0	~11
6.0 (base)	12.96
7.0	~15
8.0	~18

4.4 Sensitivity to value-of-energy (USD/kWh, blended) (single-input perturbation, indicative)

T (USD/kWh, yr-1)	Indicative simple payback (yr)
0.12	~13
0.14	~11
0.16 (base)	9.10
0.18	~8
0.20	~7

5. Scenario verdict

Multi-input scenarios (high-yield, low-yield, capex shock, tariff freeze) were NOT re-run through the scenario model on this page. They are presented qualitatively and must be re-computed at RFQ against the verified model before any go/no-go decision.

Scenario	Description	NPV (USD)	Payback (yr)	Verdict
Base (computed)	Inputs as in §1	823,748	9.10 (simple) / 12.96 (discounted)	Proceed (conditional). Positive NPV; payback inside the 25-year horizon; sensitive to tariff escalation and to the export-tariff fraction f_exp.
High-yield	Y = 1,400 kWh/kWp/yr, e = 4%, CAPEX = 1,420	Recompute at RFQ; not on this page.
Low-yield	Y = 1,100 kWh/kWp/yr, e = 1%, r = 7%	Recompute at RFQ; not on this page.
Capex shock	CAPEX = 1,800 USD/kWp, r = 8%	Recompute at RFQ; not on this page.
Tariff freeze	e = 0% real for 25 yr	Recompute at RFQ; not on this page.

6. Equipment scope and supplier guidance

This page is a generic parametric model: no specific OEM module, inverter, or racking product is asserted. Final equipment must be confirmed against supplier datasheets at RFQ. The following publicly marketed product families are credible candidates for the named roles and must be shortlisted by the buyer on technical fit (DC voltage, MPPT count, UL/IEC certifications, mounting-roof compatibility). TradVolt does not endorse any specific supplier, product, or trade-name; inclusion below is for buyer short-listing only and is not a ranking.

Modules — candidates (datasheets confirmed at RFQ):
- LONGi Hi-MO 7 series (BC, n-type back-contact) — family landing https://www.longi.com/en/; reference family Hi-MO 5m https://www.longi.com/en/products/modules/hi-mo-5m/ (LR5-72HBD / LR5-54HTH bifacial mono-PERC, datasheet revision confirmed at RFQ).
- JinkoSolar Tiger Neo — landing https://www.jinkosolar.com/en/; datasheet revision confirmed at RFQ.
- Trina Solar Vertex N — landing https://www.trinasolar.com/us-en; datasheet revision confirmed at RFQ.
String / central inverters (US C&I, 1500 V DC) — candidates:
- Sungrow SG string-inverter range — https://www.sungrowpower.com/en/products/string-inverter (incl. SG125HT 125 kW 3-phase; exact datasheet and firmware revision confirmed at RFQ).
- Huawei FusionSolar SUN2000 series — https://solar.huawei.com/en/products/sun2000-330ktl-h1 (SUN2000-330KTL-H1, 330 kW 3-phase, 1500 V DC, 8 MPPT — datasheet revision confirmed at RFQ).
- Growatt MAX / MID series — landing https://www.growatt.com/; datasheet revision confirmed at RFQ.
Flat-roof mounting — candidates:
- K2 Systems flat-roof rail/ballast family (e.g. S-Dome / D-Dome) — landing https://k2-systems.com/en/; manual revision confirmed at RFQ. K2 N-Rack ground-mount family (driven-pile + S-Rack rail): https://k2-systems.com/en/product-solutions/k2-n-rack-system/.

7. Standards & customs block

Item	Status / source
Module safety qualification (US)	REQUIRED — UL 61730-1:2017, Photovoltaic (PV) Module Safety Qualification — Part 1: Requirements for Construction (https://www.shopulstandards.com/ProductDetail.aspx?productId=UL61730-1); UL 61730-2:2017 (Part 2: Requirements for Testing). Cite full designation UL 61730-1:2017 / UL 61730-2:2017 in procurement docs.
Module performance / type approval	REQUIRED — IEC 61215 series and IEC 61730 series (designation IEC 61215-1:YYYY / IEC 61730-1:YYYY / IEC 61730-2:YYYY with year and edition in text). Look up via the IEC Webstore catalogue query: https://webstore.iec.ch/ (cite full designation, do not invent /publication/NNNN IDs).
Inverter safety / interconnect (US)	REQUIRED — UL 1741 (and IEEE 1547 for grid interconnect); confirm exact revision against the supplier datasheet at RFQ.
O&M reporting (optional, recommended)	IEC 61724-1:YYYY — cite via https://webstore.iec.ch/ with full designation IEC 61724-1:YYYY.
Module HS code (US)	8541.43 — confirm live duty rate at the USITC HTS search (https://hts.usitc.gov/) before shipment.
Inverter HS code (US)	8504.40 — confirm live duty rate at the USITC HTS search (https://hts.usitc.gov/).
Aluminium mounting HS code (US)	7610.90 — confirm live duty rate at the USITC HTS search (https://hts.usitc.gov/).
Lithium battery (if storage is later added)	UN 38.3 testing per UN Manual of Tests and Criteria, ST/SG/AC.10/11/Rev.7 (https://unece.org/transport/dangerous-goods/un-manual-tests-and-criteria).
Shipping marks	IATA Dangerous Goods Regulations (https://www.iata.org/en/programs/cargo/dgr/); ISPM 15 wood packaging, IPPC ISPM standards list (https://www.ippc.int/en/core-activities/standards-setting/ispms/).
Incoterms	Incoterms 2020 (ICC) — https://iccwbo.org/business-solutions/incoterms-rules/incoterms-2020/.

8. FAQ

Q: How long does a 900 kWp retail-park solar system pay back in the US?
A: Base case simple payback is 9.10 years; discounted payback is 12.96 years (from the COMPUTED TABLES in §2 and §3). Multi-input scenarios (high/low yield, capex shock, tariff freeze) were not re-run on this page and must be re-computed at RFQ.

Q: Which inputs drive the TCO the most?
A: Specific yield Y and the blended value-of-energy T (and, within T, the export-tariff fraction f_exp) dominate. WACC and capex are secondary drivers.

Q: Is a specific OEM module / inverter / racking system named on this page?
A: No. This page is a generic parametric model. See §6 for credible candidate product families that the buyer must shortlist against the actual site conditions and supplier datasheets.

9. Call to action

Request a fixed-price RFQ for a 900 kWp US retail-park system: /rfq/

TCO-model XLSX download is gated behind the RFQ form (/rfq/) — request once and the editable model will be sent by the TradVolt research desk; no standalone download path is published.

Disclaimer: All TCO outputs on this page are model-based and rely on the cited sources. Real-world outcomes depend on weather, financing terms, tariff policy (including any future changes to the US Investment Tax Credit), EPC execution, and operational practice. Nothing on this page constitutes financial, legal, tax, or customs advice; confirm all duty rates, certificates, and financing assumptions with the relevant licensed professional before committing to a transaction. TradVolt does not assert any third-party reviews, supplier rankings, logos, or certifications as endorsements.