AHJ Expectations Decoded: Designing for Code, Clarity, and Compliance

In solar projects, time is money, and the biggest time sink? AHJ rejections.
(AHJ = Authority Having Jurisdiction, like local building departments or utility boards.)

Design rejections during permitting can lead to:

• Weeks of delays
  
• Costly redesigns
  
• Frustrated customers
  
• Lost revenue
  

If you’re an EPC, installer, or designer, this blog walks you through how to make your designs permitting-proof from day one.

1. Know Your AHJ’s Code, Don’t Assume

Every jurisdiction has its own set of requirements:

• One city may accept rooftop setbacks of 18 inches, while another requires 36
  
• Conduit routing, interconnection formats, labeling, these can all vary
  

What to do: Keep an updated internal database of AHJ codes and review it regularly.

2. Standardize Smart, Then Customize

Templates save time, but only if they’re built to be flexible.

• Structural details may differ by region
  
• Utilities may require specific formats or labeling
  
• Fire safety paths and access zones vary
  

Build region-specific templates you can adapt quickly without starting from scratch.

3. Include What Inspectors Actually Look For

Permits are often rejected for missing key items:

• Grounding and bonding diagrams
  
• Conductor sizing and voltage drop calculations
  
• Fire setbacks and roof access compliance
  
• Equipment spec sheets that match design
  

Checklists are your best friend, use one for every submission.

4. Make It Clear and Readable

A messy drawing, even if technically correct, increases your risk of rejection.

• Use consistent line weights, legends, and sheet organization
  
• Avoid overcrowding your layout or combining too much information
  
• Label clearly and concisely
  

Permit reviewers are humans, they appreciate clarity and structure.

5. Don’t Forget the Utility

AHJs approve the design, but utilities must approve the interconnection.

• Some require energy production estimates or performance reports
  
• Others expect one-line diagrams in their proprietary format
  

Incorporate utility guidelines into your design checklist to avoid post-permit delays.

Final Thought

Permitting delays don’t just slow you down, they affect cash flow, customer experience, and scalability.
Design for performance, but prepare for approval.
Permitting-proof designs are not a luxury, they’re a necessity.