Professional Engineer (PE) stamping is one of the most misunderstood aspects of US solar permit design. When does a solar project actually require a PE stamp? Which discipline of PE? Which state jurisdiction's PE license? What is the difference between structural and electrical PE stamping? How do multi-state solar EPCs manage PE coverage without hiring engineers in every state?
This guide walks through the practical reality of PE stamping for solar plan sets in the United States, based on how the requirements actually work across state jurisdictions, AHJs, and utilities.
What is a PE stamp and why do solar projects need one?
A Professional Engineer (PE) is a licensed engineer authorized to practice engineering in a specific state, having passed the Fundamentals of Engineering (FE) exam, gained the required professional experience (typically four years), and passed the Principles and Practice of Engineering (PE) exam in a specific discipline.
A PE stamp (or seal) on a solar plan set is the engineer's professional attestation that the design meets applicable codes and standards. The stamp carries legal weight: the PE takes personal professional responsibility for the design.
For solar projects, the two disciplines that stamp plan sets are:
- Electrical PE: stamps the electrical design (SLD, conductor sizing, overcurrent protection, grounding, interconnection design)
- Structural PE: stamps the structural design (racking selection, roof loading, attachment design, foundation for ground mounts)
Some jurisdictions accept a single PE stamp from an engineer licensed in the appropriate discipline to cover both aspects. Others require separate stamps for electrical and structural work. Some states use a single "Professional Engineer" license without discipline restrictions, allowing any PE to stamp any engineering document within their competence.
When does a US solar project require a PE stamp?
PE stamping requirements are set at the state level and further modified by individual AHJs and utilities. There is no single national rule. The general patterns are:
Always requires PE stamp
- All commercial and multi-family solar projects in most states
- Any project over a certain kW threshold (varies by state and AHJ, common thresholds are 10 kW, 15 kW, 20 kW, or 25 kW for residential)
- Ground-mount systems in most jurisdictions regardless of size
- Any project connecting at commercial voltage levels
- Projects in jurisdictions with strict PE requirements (NYC, Boston, and other major cities)
- Projects with battery energy storage above a jurisdiction-specific threshold
Sometimes requires PE stamp
- Residential rooftop projects between certain kW ranges (varies widely by AHJ)
- Projects with unusual structural conditions (aging roofs, non-standard rafters, historic buildings)
- Projects in coastal or high-wind zones where structural loading is unusually critical
- Projects using non-standard racking or attachment methods
Typically does not require PE stamp
- Small residential rooftop projects below the jurisdiction's threshold using standard racking on standard truss construction
- Projects submitted under state-wide simplified permit programs (such as certain unified solar permit formats)
The specific thresholds and rules vary by jurisdiction. Always check the AHJ where your project is located for the current PE stamping requirement.
Which state's PE license is required?
This is where multi-state solar EPCs run into complexity. The general rule is: the PE stamping a plan set must be licensed in the state where the project is located, not the state where the engineer resides.
A PE licensed in California cannot stamp a plan set for a project in New Jersey unless that engineer also holds a New Jersey PE license. This means a solar EPC operating in ten states needs access to PEs licensed in all ten of those states (either in-house or through PE-of-record partnerships).
Two mechanisms exist for a PE to become licensed in an additional state:
- Comity or reciprocity: most states allow a PE licensed in another state to apply for a license in the new state by demonstrating equivalent qualifications, without needing to retake the PE exam.
- NCEES record: the National Council of Examiners for Engineering and Surveying maintains a portable engineering record that streamlines multi-state licensure applications.
Even with these mechanisms, obtaining PE licensure in a new state takes weeks to months and involves state-specific application fees, background checks, and sometimes state-specific ethics exams.
State-by-state general PE stamping patterns for solar
Rather than providing specific rules that shift constantly, here is the general pattern across major solar markets. Always verify with the actual AHJ for current requirements:
- Northeast (NY, NJ, CT, MA, RI, PA): generally strict on PE stamping. NYC requires PE or RA (Registered Architect) stamping on essentially all solar permits. Many suburban jurisdictions require PE stamping above 10-15 kW residential. Commercial almost always requires PE stamping.
- Mid-Atlantic (MD, DE, VA, DC): generally requires PE stamping for commercial and larger residential projects. Some smaller residential exempted.
- Southeast (FL, NC, SC, GA): Florida requires PE stamping on almost all solar projects, particularly with strict HVHZ requirements in South Florida. Other Southeast states generally require PE stamping above jurisdiction-specific thresholds.
- Midwest (OH, IN, IL, MI, WI, MN): varies widely. Chicago and other large cities typically strict; smaller AHJs often follow simpler patterns.
- Southwest (TX, AZ, NM, NV, OK): Texas municipalities vary; Arizona is generally strict on commercial. Nevada tends to require PE for commercial and larger residential.
- West Coast (CA, OR, WA): California has structured requirements varying by jurisdiction; most commercial and larger residential requires PE. Washington and Oregon similarly require PE stamping on commercial and larger residential.
- Mountain West (CO, UT, ID, MT, WY): generally requires PE for commercial, varies on residential thresholds.
These are general patterns. Always check your local AHJ for the currently enforced PE stamping requirement.
Structural PE vs Electrical PE for solar
The distinction matters because a solar plan set has both electrical and structural elements:
- Electrical: SLD, conductor sizing, overcurrent protection, grounding, disconnects, labeling, interconnection design
- Structural: racking selection, wind and snow load analysis, roof attachment design, penetration details, foundation design (for ground mounts)
Different jurisdictions treat this differently:
- Combined stamp: some AHJs accept a single PE stamp covering both electrical and structural work, particularly for smaller residential projects
- Separate stamps: larger commercial projects and stricter jurisdictions require both an electrical PE and a structural PE to stamp their respective sections
- Structural PE only: where the electrical design is straightforward and follows standard patterns, some AHJs primarily focus on structural stamping
Always confirm the specific requirement with the AHJ before assigning the stamp.
How multi-state solar EPCs manage PE coverage
Solar EPCs and installers operating in multiple US states face a real operational challenge: maintaining PE coverage across every state where they submit permits. Common approaches:
- In-house multi-state PE: hire a PE who holds licenses in your top target states. Expensive but gives full control. Costs typically run $110,000-$140,000+ per year for a US-based PE with multi-state licensure.
- PE-of-record partnerships: contract with independent PE firms in each state you operate in. Pay per plan set stamped. Fees vary widely, typically $150-$600+ per residential plan set and $500-$3,000+ per commercial plan set depending on complexity.
- Outsourced design plus PE-of-record: an outsourced design partner produces the plan sets to PE-ready standard, then routes them to appropriate PE-of-record firms for stamping in each jurisdiction. This bundles design and PE management for the EPC.
How outsourced solar design fits into the PE stamping workflow
Outsourced solar design does not replace the need for a PE stamp. What it does is deliver plan sets that are PE-ready: fully compliant with the applicable codes, laid out to standard, calculated correctly, and formatted for the target AHJ. The reviewing PE receives a plan set that requires minimal changes before stamping.
This model works because:
- The outsourced design team maintains code and template expertise across all jurisdictions
- The PE-of-record firm reviews, provides feedback, and applies the stamp
- The EPC pays a lower blended cost than maintaining in-house engineers plus in-house PEs
RIH Engineering delivers outsourced solar PV design to PE-ready standard for US EPCs, installers, developers, and roofing companies. Our plan sets are produced against the codes and templates required in each project's jurisdiction. If you want to talk through how outsourced design plus PE-of-record can work in your workflow, get in touch.
Frequently asked questions
When does a US solar project require a PE stamp?
PE stamping requirements are set at the state and AHJ level. Commercial solar and larger residential projects (typically above 10-25 kW, depending on jurisdiction) almost always require PE stamping. Small residential systems below the threshold may not. Always check the AHJ where the project is located.
Does the PE need to be licensed in the project's state?
Yes. A PE stamping a solar plan set must be licensed in the state where the project is located, not where the engineer resides. Multi-state solar EPCs need access to PEs licensed in each state they operate in, either in-house or through PE-of-record partnerships.
What is the difference between electrical PE and structural PE for solar?
Electrical PE covers the electrical design (SLD, conductor sizing, overcurrent, grounding, interconnection). Structural PE covers the structural design (racking, roof loading, attachment). Some jurisdictions accept combined stamping; others require separate stamps. Confirm with your AHJ.
Can outsourced solar design partners provide PE stamps?
Outsourced design partners typically deliver PE-ready plan sets that meet all applicable codes and standards, but the PE stamp is applied by a licensed engineer of record. The outsourced design plus PE-of-record model is common and cost-effective for multi-state EPCs.
How do I get PE stamps for solar plan sets in multiple states?
Three common approaches: hire an in-house PE with multi-state licensure, contract with PE-of-record firms in each target state, or use an outsourced design partner who works with PE-of-record firms across the states you operate in.