Every solar installation in the U.S. must comply with the National Electrical Code (NEC). For contractors and installers, understanding NEC requirements is not optional—it’s the foundation of a permit-ready solar design. Whether you’re working on a residential rooftop system or a large commercial project, inspectors and AHJs (Authorities Having Jurisdiction) look to NEC compliance as a key approval standard.
This guide breaks down the most important NEC Articles that impact solar permitting and explains how contractors can stay compliant while speeding up approvals.
What Is the NEC and Why Does It Matter in Solar?
The National Electrical Code (NEC) is the U.S. standard for safe electrical design and installation. Updated every three years by the NFPA (National Fire Protection Association), it sets rules that solar contractors must follow to:
- Ensure electrical safety for customers and installers
- Provide consistency across jurisdictions
- Reduce risks of permit rejection or project delays
- Simplify utility interconnection approvals
For solar permitting, NEC compliance is non-negotiable. AHJs use NEC codes as their reference when reviewing designs.
Key NEC Articles for Solar Permit Design
1. NEC Article 690 – Solar Photovoltaic Systems
- Governs PV system wiring, overcurrent protection, and disconnects
- Requires clear labeling of DC circuits
- Defines rapid shutdown requirements for rooftop systems
Permit Impact: Designs must show compliant string sizing, fuses, and labeling.
2. NEC Article 705 – Interconnected Electric Power Production Sources
- Covers interconnection of PV systems with the utility grid
- Explains rules for load-side and supply-side connections
- Defines backfeed and breaker sizing rules
Permit Impact: Inspectors check your SLDs (Single-Line Diagrams) for correct breaker sizing and busbar calculations.
3. NEC Article 706 – Energy Storage Systems
- Applies to battery integration with solar
- Requires UL-listed batteries, proper disconnects, and fault protection
- Defines labeling and isolation rules for hybrid systems
Permit Impact: Storage-inclusive projects must include UL 9540 battery cut sheets and detailed control diagrams.
4. NEC Article 110 – General Requirements
- Outlines basic safety rules for equipment installation
- Requires listed and labeled equipment
- Covers working clearances and accessibility
Permit Impact: AHJs often reject designs that lack UL-listed equipment specifications.
5. NEC Article 250 – Grounding and Bonding
- Details grounding requirements for PV modules, racks, and inverters
- Prevents electrical faults and fire risks
Permit Impact: Grounding methods must be shown clearly in electrical diagrams.
Common NEC Mistakes That Delay Permits
- Incorrect string sizing or voltage calculations under Article 690
- Busbar overloads due to misapplied 120% rule under Article 705
- Submitting non-UL listed batteries in Article 706 projects
- Missing or incorrect rapid shutdown labeling
- Incomplete grounding diagrams under Article 250
How Contractors Can Stay NEC-Compliant
- Use updated NEC editions (some AHJs adopt later versions faster than others).
- Standardize permit templates with NEC requirements built-in.
- Train design teams on Articles 690, 705, and 706.
- Partner with engineering experts for PE-stamped drawings.
- Submit complete documentation—reducing AHJ redlines.
How Vishtik Helps Contractors with NEC Compliance
At Vishtik, we specialize in creating NEC-compliant solar permit packages that pass AHJ review the first time. Our services include:
- NEC 690, 705, and 706–compliant electrical drawings
- Rapid shutdown and labeling layouts
- UL-listed equipment integration
- PE-stamped documents for structural and electrical approval
- Fast turnaround to avoid project delays
With our expertise, contractors can focus on installation while we handle the engineering precision needed for approvals.
Conclusion
The National Electrical Code is the backbone of solar permitting. By understanding Articles 690, 705, 706, and others, contractors can design safer systems, reduce permit rejections, and speed up project timelines. With Vishtik as your partner, NEC compliance becomes effortless.
Need NEC-compliant solar drawings for your next project? Connect with Vishtik today.
