The United States is the world’s second-largest solar market — but compliance here is unusually fragmented. Unlike countries with a single national permitting authority, US solar projects must navigate federal electrical codes, state net metering rules, local AHJ permits, and utility interconnection requirements simultaneously. No two states are identical.
This guide covers everything a solar installer needs to know: the electrical code framework, the permitting process, federal incentives under the IRA, and the specific rules that differ state by state.
Market Scale
The US installed 32.4 GW of solar in 2024, bringing cumulative capacity to over 200 GW. Residential solar alone added 6.1 GW. With the IRA locked in through 2032, projections call for 50+ GW annual additions by 2027. The compliance framework is the foundation every installer works within.
The US Solar Compliance Framework
US solar compliance operates on three levels:
| Level | Who Sets It | What It Covers |
|---|---|---|
| Federal | NFPA (NEC) + IRS (IRA) | Electrical safety standards + tax incentives |
| State | State legislature / PUC | Net metering, interconnection, licensing |
| Local | AHJ (city/county) | Building permits, plan review, inspections |
All three levels apply to every project. A California residential system, for example, must comply with NEC 2020 (as amended by the California Electrical Code), California’s NEM 3.0 tariff, and the specific permit requirements of the local city or county building department.
NEC Article 690: The Electrical Standard
NEC Article 690 is the national baseline for solar PV electrical safety. It covers:
- 690.7 — Maximum PV system voltage (600V residential, 1000V commercial)
- 690.8 — Circuit current and conductor sizing (125% of Isc rule)
- 690.9 — Overcurrent protection
- 690.12 — Rapid shutdown for building-mounted systems
- 690.31 — Wiring methods (PV wire, USE-2, conduit)
- 690.41 — Ground fault protection
- 690.43 — Equipment grounding
- 690.56 — Identification of power sources
The NEC is updated on a three-year cycle. As of 2026:
| State | Current NEC Edition |
|---|---|
| California | NEC 2020 (as amended by CEC) |
| Texas | NEC 2020 |
| Florida | NEC 2020 |
| New York | NEC 2020 |
| Arizona | NEC 2020 |
| Colorado | NEC 2020 |
| New Jersey | NEC 2017 |
| Massachusetts | NEC 2020 |
| North Carolina | NEC 2020 |
| Nevada | NEC 2020 |
A few jurisdictions have adopted NEC 2023, which introduced significant changes to ground-mounted system grounding requirements and added new provisions for energy storage systems. Always confirm the applicable edition with your AHJ before starting design.
Design to the Right Edition
Using software that auto-selects NEC calculations based on jurisdiction saves significant rework time. Design tools that output 690.7 voltage calculations and 690.8 ampacity tables reduce AHJ revision cycles.
The Permitting Process: AHJ Basics
Every solar installation in the US requires a permit from the Authority Having Jurisdiction (AHJ) — typically the city or county building department. The permit process covers:
- Plan review — AHJ reviews electrical drawings, site plans, and equipment specs for code compliance
- Permit issuance — AHJ approves the plans and issues a permit number
- Inspection — AHJ inspector visits the site to verify the installation matches approved plans
- Permission to operate (PTO) — Utility issues final authorization to energize and grid-connect
Turnaround times vary widely:
| Jurisdiction Type | Typical Plan Review Time |
|---|---|
| Large urban city (manual) | 3–6 weeks |
| Suburban county (online portal) | 1–2 weeks |
| SolarAPP+ participating AHJ | Same day (automated) |
| Expedited/over-the-counter | 1–3 days |
SolarAPP+: Automated Permit Review
SolarAPP+ (Solar Automated Permit Processing Plus) is a free tool from NREL that provides instant plan review approvals for residential rooftop solar systems under 15 kW. Over 250 AHJs had adopted SolarAPP+ by early 2026, including major jurisdictions in California, Colorado, and Florida.
A SolarAPP+ approval can replace a traditional plan review — the installer submits system parameters online and receives a stamped approval certificate in minutes. This reduces permit delays from weeks to hours for qualifying projects.
SolarAPP+ Eligibility
SolarAPP+ works for residential rooftop solar systems up to 15 kW on single-family homes. Ground-mounted systems, commercial systems, and battery storage add-ons require traditional plan review regardless of participating AHJ status.
Federal Incentives: The Inflation Reduction Act
The Inflation Reduction Act (IRA) of 2022 is the largest climate legislation in US history. It restructured and extended solar tax incentives through 2032 and beyond.
Investment Tax Credit (ITC)
| System Type | Base ITC | With Domestic Content | With Energy Community |
|---|---|---|---|
| Residential (Section 25D) | 30% | N/A | N/A |
| Commercial (Section 48E) | 30% | 40% | 40% |
| Utility-scale (Section 48E) | 30% | 40% | 40% |
| Community solar (Section 48E) | 30% | 40% | 40% |
The 30% base ITC is available through 2032 for all system types. For commercial and utility projects, bonus credits stack: a system in an energy community using domestic content modules can claim up to 50% ITC.
Residential ITC Rules (Section 25D)
- Credit is 30% of total installed cost, including equipment, labor, and permitting
- No income cap, no system size cap
- Applies to primary and secondary residences
- Battery storage added to an existing solar system qualifies for the full 30% ITC
- Unused credit carries forward to future tax years
- Claimed on IRS Form 5695
Commercial ITC Rules (Section 48E)
- Applies to all commercial, industrial, and utility-scale systems
- Prevailing wage and apprenticeship requirements must be met for projects above 1 MW AC (to unlock the full 30% vs. the 6% base)
- Domestic Content Bonus: 10% additional if 40%+ of steel/iron and 40%+ of manufactured components are US-made
- Energy Community Bonus: 10% additional for projects in census tracts meeting brownfield, fossil fuel employment, or coal mine closure criteria
- Claimed on IRS Form 3468
Bonus Credit Stacking
Commercial projects can stack the base 30% + 10% domestic content + 10% energy community for a total 50% ITC. The prevailing wage requirement is the primary compliance hurdle — document wage rates from project start, not just at filing.
Net Metering: State-by-State Rules
Net metering compensates solar system owners for excess electricity exported to the grid. The rules are entirely state-controlled — there is no federal net metering mandate.
Major State Net Metering Programs
| State | Program | Compensation Rate | Key Notes |
|---|---|---|---|
| California | NEM 3.0 | ~$0.05–0.08/kWh (varies by TOU) | Moved from retail-rate in April 2023. Battery storage now central to economics. |
| Texas | Varies by utility | Avoided cost to retail | No statewide mandate. Austin Energy, CPS, and Oncor have different programs. |
| Florida | Net metering | Retail rate | Legislature attempted to phase out retail rate in 2022; courts restored it. |
| New York | Value of Distributed Energy Resources (VDER) | Varies by utility + location | Complex formula-based compensation, not simple retail rate |
| New Jersey | Net Metering Plus (NEM+) | Full retail rate | Plus SREC II program for additional revenue |
| Massachusetts | Net Metering | Retail rate + SMART incentive | Both programs available simultaneously |
| Arizona | Excess Energy Credit | Below retail (~$0.09/kWh) | APS and TEP have different rates |
| Colorado | Net Metering | Retail rate | Xcel Energy largest utility; strong net metering |
California NEM 3.0 Impact
California’s shift to NEM 3.0 in April 2023 fundamentally changed the residential solar economics. Export compensation dropped by roughly 75% compared to NEM 2.0 retail rates. New systems in California should be designed with battery storage to maximize self-consumption. The payback period without storage extended from 6–8 years to 9–12 years under NEM 3.0.
State Licensing Requirements
Solar installers must be licensed in each state where they work. Requirements vary:
| State | Required License | Issuing Authority |
|---|---|---|
| California | C-10 (Electrical) or C-46 (Solar) | California Contractors State License Board |
| Texas | Master Electrician license | Texas Department of Licensing and Regulation |
| Florida | Solar Contractor (EC-13) or Electrical (EC) | Florida DBPR |
| New York | Home Improvement Contractor + Electrician | NYC: DOB; State: varies by municipality |
| New Jersey | Home Improvement Contractor + Electrician | New Jersey Division of Consumer Affairs |
| Massachusetts | Construction Supervisor + Electrical license | Massachusetts OCABR |
| Arizona | Residential/Commercial Contractor + Solar | Arizona Registrar of Contractors |
| Colorado | Electrical Contractor | Colorado State Electrical Board |
NABCEP (North American Board of Certified Energy Practitioners) certification is widely recognized across states and often accelerates AHJ plan review. The NABCEP PV Installation Professional (PVIP) credential is the industry standard.
Interconnection Standards
IEEE 1547-2018
IEEE 1547-2018 is the US standard for interconnecting distributed energy resources (DERs) to the grid. It replaced the 2003 version and introduced major changes:
- Expanded voltage and frequency ride-through requirements (systems must stay online during grid disturbances rather than immediately disconnecting)
- Reactive power capability requirements for larger systems
- State-of-the-art communications requirements for systems above 500 kW
All inverters sold in the US since approximately 2021 are IEEE 1547-2018 compliant. Most utilities require 1547-2018 compliance as a condition of interconnection.
FERC Order 2222
FERC Order 2222 (issued 2020, implementation ongoing) requires wholesale electricity markets to allow aggregated DERs — including residential solar+storage — to participate as grid resources. This opens revenue opportunities for virtual power plant aggregators and is relevant for large commercial and community solar projects.
Design Tools and Software
Compliant solar design in the US means producing documentation that satisfies both the NEC electrical requirements and the AHJ’s documentation requirements simultaneously.
Key outputs required for US permit packages:
- Three-line or single-line electrical diagram with all 690.7/690.8 calculations annotated
- String sizing table showing Voc (corrected), Vmp, Isc, and Imp for each string
- Rapid shutdown compliance documentation
- Equipment cut sheets for modules, inverter, racking, and combiner boxes
- Site plan showing array location, setbacks, and access pathways
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All US Solar Compliance Pages
Frequently Asked Questions
What code governs solar PV installations in the US?
NEC Article 690 is the primary electrical code for all US solar PV systems. It is part of NFPA 70 (National Electrical Code) and covers system voltage, conductor sizing, rapid shutdown, ground fault protection, and disconnecting means. States adopt a specific NEC edition — most jurisdictions are on 2017 or 2020 as of 2026.
Do I need a permit for every solar installation?
Yes. Every US solar PV installation requires a building permit from the local AHJ. The complexity of the permit application varies by system size and jurisdiction. SolarAPP+ automates approvals for residential systems under 15 kW in participating jurisdictions.
What is the federal solar tax credit in 2026?
The IRA Investment Tax Credit provides 30% of total system cost for residential systems (Section 25D) and commercial systems (Section 48E) through 2032. Commercial systems in energy communities or using domestic content equipment can claim up to 50% ITC with bonus credits.
How does net metering work?
Net metering is state-controlled. Most states compensate solar export at or near retail rates, but California moved to a lower export rate under NEM 3.0 in 2023. Texas has no statewide net metering mandate. Rules change frequently — always check the current tariff for the specific utility.
