IRA Prevailing Wage & Apprenticeship (PWA) Rules & The <1 MW AC Exemption
Under the Inflation Reduction Act, the technical 'base' commercial solar tax credit is only 6%—multiplied by 5x to **30%** if the project either (A) has a maximum net output of **less than 1 Megawatt AC (<1,000 kW AC)**, OR (B) pays Davis-Bacon Prevailing Wages and uses 15% Registered Apprentice labor hours during construction and for 5 years of post-install alterations/repairs!
Key IRS Statutory & Treasury Regulation Takeaways
- ✓The <1 MW AC Statutory Exemption (Why C&I Developers Size Inverters at 990 kW AC!): Any solar project with a total AC inverter nameplate rating under 1.0 MW AC (~1.35 MW DC of solar panels!) is **100% EXEMPT** from Prevailing Wage and Apprenticeship (PWA) requirements and gets the full 30%–50% credit automatically!
- ✓How the 1 MW AC Test Works for Co-Located Battery Storage: Under Treasury final regulations, the 1 MW AC threshold is measured solely on the **generation source (the solar inverter AC output)**, or for standalone storage, <1 MW of inverter capacity—allowing massive commercial systems to stay exempt.
- ✓Rules for Projects ≥1 MW AC: Every laborer and mechanic employed by the EPC contractor and every subcontractor must be paid at least the Department of Labor (sam.gov) Davis-Bacon prevailing wage for their county and trade classification, AND 15% of total labor hours must be performed by qualified apprentices from a DOL/State registered apprenticeship program.
- ✓The 'Good Faith Effort' Apprenticeship Exception & Cure Penalties: If a contractor requests apprentices in writing from a registered program and the request is denied or not answered within 5 business days, the contractor qualifies for the Good Faith Effort exception for 365 days!
Step-by-Step IRS Pre-Filing Registration & Compliance Timeline
| Milestone Step | Timing Window | IRS Portal / Tax Form | Critical Compliance Rule |
|---|---|---|---|
| 1. Determine Project AC Nameplate Capacity (<1,000 kW AC vs ≥1,000 kW AC) | At Engineering Design Stage | Inverter Nameplate Spec Sheet (UL 1741 Rating) | If total AC inverter output is 999 kW AC or less (even with 1,400 kW DC of panels!), PWA does not apply! |
| 2. Lock In sam.gov Wage Determinations (If ≥1 MW AC) | On Date Construction Contract Is Executed | sam.gov County Wage Determination PDF | Require weekly Certified Payroll Reports (WH-347) and 4:1 / 5:1 apprentice-to-journeyworker ratio logs from all subcontractors. |
| 3. File IRS Form 7218 With Tax Return | Filed with Form 3468 / Form 3800 | IRS Form 7218 | Maintains 5-year post-commissioning prevailing wage compliance for any major capital repairs (routine O&M/washing is exempt). |
Real-World Capital Stack & Tax Credit Pro-Forma Example
1.35 MW DC / 996 kW AC Commercial Warehouse Solar System (Engineered Under 1 MW AC Limit)
Financial & Structural Advantages
- +The <1 MW AC exemption covers 98% of all behind-the-meter commercial, agricultural, school, and church solar installations!
- +Routine maintenance, panel washing, and warranty inspections are EXEMPT from the 5-year post-install prevailing wage rule
- +Unintentional wage underpayments on ≥1 MW projects can be legally cured by paying back wages + interest + a $5,000/worker penalty rather than losing the entire 30% credit
IRS Audit & Compliance Watchouts
- −On projects ≥1 MW AC, selling the tax credit under § 6418 requires a clean Third-Party CPA PWA Audit Report for the credit buyer
Frequently Asked Questions
If we install 1,300 kW DC of solar panels connected to 990 kW AC of inverters, are we exempt from Prevailing Wage and Apprenticeship?
YES! The statutory 1-megawatt threshold in IRC § 48(a)(9)(B)(i) and § 48E(d)(3)(A) is explicitly defined as 'maximum net output of less than 1 megawatt (as measured in alternating current)'. Because solar systems typically use a 1.30 to 1.35 DC-to-AC ratio, a 990 kW AC inverter system can support up to ~1,330 kW DC of solar panels while remaining 100% exempt from PWA!
What if we own two warehouses on different parcels—are their kW capacities combined for the 1 MW AC test?
No, unless they are contiguous parcels operating as a single integrated facility under the IRS 'Single Project' factors (contiguous land, single interconnection point, single substation/permit).
Modeling a Commercial Solar, Rural USDA REAP, or EV Fleet Charging Project?
Use our USDA REAP Grant Calculator or EV Fleet Demand Charge Sizer to build a complete 10-year CFO pro-forma.