Verdict (base case, US commercial gym, 80 kWp rooftop PV, 25-year horizon, evidence date 2026-01-15): Simple payback (undiscounted) = 14.41 years; discounted payback at r = 7.00% = none within the 25-year horizon; NPV @7.00% over 25 years = USD -30,626.50; LCOE = USD 0.1628/kWh. The base case is NPV-negative at the 7% discount rate over 25 years; the project only returns capital within the analysis window on an undiscounted basis. Limitation: vendor-neutral inputs; replace with site-specific yield, tariff, and capex for procurement.

Use Case & TCO: 80 kWp Gym Rooftop Solar in the United States (Revision 9)

A commercial gym is an attractive candidate for rooftop PV: daytime HVAC load, lighting baseload, and a flat or low-slope roof that can usually accept 80 kWp without a structural redesign. This page models capex, yield, opex, and payback for an 80 kWp array at a US commercial gym. The model is vendor-neutral: no specific module or inverter OEM is implied. Inputs are cited; the TCO summary and 25-year cashflow below are the computed outputs and are computed. The page is sensitive to installed cost, specific yield, self-consumption share, and retail tariff.

1. Computed TCO summary (computed)

2. Year-by-year cash flow (computed)

3. Inputs (cited; vendor-neutral)

The page is vendor-neutral: no specific module family or inverter OEM is implied. Generic module/inverter performance is used to populate the computed table. Real product references are presented in Section 6 only as illustrative examples of publicly-marketed equipment that an actual gym might substitute; their datasheet performance is not assumed here.

4. Formulae (transparent)

Annual energy in year t (kWh):

E(t) = Pdc × Y × (1 - D)^(t-1)

Annual savings in year t (USD), with tariff and O&M escalation at rate g = 0.02:

Sav(t) = E(t) × S × T × (1 + g)^(t-1) + E(t) × (1 - S) × Ee × (1 + g)^(t-1) - Om × (1 + g)^(t-1)

where Ee is the export price (USD/kWh) and Om is the Year-1 O&M cost.

Capex (USD):

Capex = Pdc × 1000 × C

Simple payback (years): year in which cumulative undiscounted savings first equals Capex. Discounted payback (years): year in which cumulative discounted savings first equals Capex, using discount factor (1 + r)^t. Both are reported in the TCO summary and decision table.

Net Present Value over N years:

NPV = -Capex + Sum_{t=1..N} Sav(t) / (1 + r)^t

Note: capex is shown pre-incentive. The US federal Investment Tax Credit (ITC) under the Inflation Reduction Act of 2022 provides a base 30% credit for qualifying commercial PV; bonus adders (domestic content, energy communities, low-income) may apply. The base-case computed table excludes ITC so the underlying economics are visible. Apply ITC by multiplying Capex by (1 - 0.30) for the base credit; the resulting ITC-adjusted simple payback lies between the base-case values and must be verified with a tax professional. ITC must be applied on either the discounted or the undiscounted series, not both, to avoid double-counting.

5. Sensitivity table (year-1 net savings)

Each cell shows Sav(1) in USD, recomputed from the stated formula at g = 0:

Sav(1) = Pdc × Y × S × T + Pdc × Y × (1 - S) × Ee - Om

Worked example for the lowest cell: 80 × 1,200 × 0.55 × 0.10 = 5,280; 80 × 1,200 × 0.45 × 0.06 = 2,592; total 7,872 - 1,400 = 6,472 USD.

Capex by cost band (USD):

6. Illustrative equipment references (not assumed in the computed table)

The computed table above is vendor-neutral. The following are real, publicly marketed products that an actual gym-rooftop project might substitute. Their public datasheets or product pages are linked. No claim is made that these products were used in, or are endorsed for, the base case.

• LONGi Hi-MO 5 / Hi-MO 6 mono-PERC and back-contact module families; product datasheets published on the LONGi site.
• JinkoSolar Tiger Neo / Tiger Pro module families; product datasheets published on the Jinko site.
• Trina Solar Vertex / Vertex S+ module families; product datasheets published on the Trina site.
• Sungrow SG string inverter families (commercial-scale three-phase); product datasheets published on the Sungrow site.
• Huawei FusionSolar SUN2000 string inverter families; product datasheets published on the Huawei site.
• Growatt commercial string inverter families; product datasheets published on the Growatt site.

Choose equipment only after confirming the model family, datasheet revision, and torque/SOC/voltage limits against the OEM manual at the RFQ stage.

7. Mini certification block (informational only; no specific shipment is certified)

• Modules: UL 61730-1 Photovoltaic (PV) Module Safety Qualification - Part 1, and IEC 61215 / IEC 61730 series (issued by UL LLC; verify the certificate number per shipment against the UL 61730-1 standard page and the IEC Webstore IEC catalogue).
• Inverters: UL 1741 (issued by UL LLC) and IEEE 1547 series (issued by IEEE); verify certificate number per shipment.
• Installation: NFPA 70 (National Electrical Code, NEC 690) and NFPA 70E; racking UL 2703 (issued by UL LLC). Verify local AHJ adoption.
• Installer: NABCEP PV Installation Professional certification recommended; verify individual certification number on the NABCEP registry.
• Grid interconnection: state PUC rules and the local utility interconnection agreement; verify with the serving utility.

This block is informational. It does not certify any specific shipment, and the absence of a certificate number above is intentional. Always confirm the certificate revision, edition, and issuing body against the standard page linked.

8. HS code lookup (PENDING rates; use the linked lookup tool)

Lookup instructions:

1. Open the USITC Harmonized Tariff Schedule search: hts.usitc.gov.
2. Enter the HTSUS number above and read the current General Duty rate in chapter 99 notes.
3. Confirm Section 201 safeguard tariffs and Section 301 China-origin tariffs where applicable (refer also to US Customs and Border Protection).
4. Confirm FTA preference eligibility (USMCA and FTA partners) via US International Trade Administration if relevant.
5. Verify via a binding Customs ruling or a licensed customs broker before import.

Disclaimer: the duty rates above are marked PENDING and must not be treated as fact. TradVolt does not provide legal or customs advice. Always confirm rates against the USITC HTS lookup and a licensed customs broker.

9. RFQ

Single RFQ anchor - request a bound quote for an 80 kWp gym rooftop system, US site, with your interconnection utility and roof survey:

Request a formal RFQ for the 80 kWp US gym solar package »

10. Sources cited

• NREL, Best Practices for PV System Performance (PVPMC), NREL/TP-5K00-85022: https://www.nrel.gov/docs/fy23osti/85022.pdf
• NREL PVWatts calculator: https://pvwatts.nrel.gov/
• NREL, U.S. Solar Photovoltaic System and Energy Storage Cost Benchmarks (Ramasamy et al., 2023), NREL/TP-5K00-87303: https://www.nrel.gov/docs/fy23osti/87303.pdf
• U.S. EIA, Electric Power Monthly, Table 5.1.A (Commercial sector average price): https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_es1a
• Inflation Reduction Act of 2022, Section 48 ITC (base 30% credit; verify bonus adders with a tax advisor).
• USITC Harmonized Tariff Schedule search: https://hts.usitc.gov/
• US Customs and Border Protection: https://www.cbp.gov/
• US International Trade Administration: https://www.trade.gov/
• UL 61730-1 Photovoltaic (PV) Module Safety Qualification - Part 1 (UL LLC): https://www.shopulstandards.com/ProductDetail.aspx?productId=UL61730-1
• IEC Webstore (catalogue for IEC 61215, IEC 61730, IEC 61851-1 and related standards): https://webstore.iec.ch/

TradVolt RFQ form: https://tradvolt.com/rfq/