®Fewer permit rejections
Drawings and calculations get built to the specific AHJ's standard from the start, instead of a generic package that comes back redlined.
Services for the solar trade
Engineering & design
Permit packages, interconnection studies and structural calculations produced to the standard an AHJ or utility actually checks against.
Engineering & design
Permit packs, shading analytics and single-line diagrams.
Where projects clear review faster
Move faster through interconnection
Technical review and application support target the exact utility's process instead of a one-size interconnection filing.
Catch design conflicts before the field does
BIM and clash detection surface a structural or routing conflict on screen instead of on a ladder.
Permit Pack Drafts
Complete permit packages built to the specific AHJ reviewing them, not a generic template that comes back redlined.
Complete permit packages built to the AHJ
A full package, not a partial one
Site plan, structural attachment detail, single-line diagram, equipment specs and NEC labeling all draft as one package, since a permit reviewer checks all of it, not just the roof layout.
Built to the specific jurisdiction
Requirements vary meaningfully between AHJs, and packages here are drafted against the specific jurisdiction's checklist rather than a one-size template that draws a redline in a stricter jurisdiction.
NEC 2023 detail built in from the start
Rapid-shutdown labeling and arc-fault protection detail are drawn into the package from the first draft, since that's where a large share of permit rejections actually originate.
Fewer rejections, predictable turnaround
Cut rejections at the first submission
Jurisdiction-specific requirements and NEC detail are built into the initial draft instead of getting corrected after a redline.
Predictable turnaround
Permit packages move through a defined production timeline instead of an open-ended design queue.
Shading & Production Analytics
Yield modeling that accounts for real shading obstructions, so a production estimate holds up against actual site conditions.
Site-specific shading and production modeling
Site-specific modeling, not a flat derate
Trees, adjacent structures and roof geometry get modeled against actual sun-path data for the site, replacing a generic shading percentage that either overstates or understates real production.
Feeds directly into string and inverter design
Shading results inform how strings get grouped and whether module-level power electronics make sense for a given roof, rather than sitting in a separate report nobody references during design.
Deliverables built for financing and warranty conversations
Production estimates come with the documentation a financing partner or a performance-guarantee conversation actually asks for.
Production numbers and string design that hold
Quote a production number that holds up
Modeled shading data replaces a generic derate, so year-one production estimates match what the system actually delivers.
Design strings around real shading patterns
String grouping and MLPE decisions get made with actual shading data, not a guess.
Single-line Diagrams (SLD)
Single-line diagrams built to the NEC and utility standard a permit reviewer and an interconnection engineer both need to see.
Diagrams built for permit and utility review
Built for two audiences at once
A single-line diagram has to satisfy both a local AHJ's permitting checklist and a utility's interconnection engineering review, and drawings here are built to both standards from the start instead of requiring a second version.
NEC-compliant labeling and equipment detail
Overcurrent protection, disconnects and equipment ratings are documented to the level of detail NEC 2023 and most utility interconnection standards expect.
PE stamped where required
Structural and electrical stamping requirements vary by state and utility, and SLDs here are stamped to match what the specific project's jurisdiction and interconnecting utility require.
One drawing, two approvals, fewer redlines
One drawing, two approvals
A single SLD built to both AHJ and utility standards avoids drafting two separate versions.
Fewer redlines on technical review
Equipment detail and labeling match what reviewers actually check for the first time.
Structural Calculations
Stamped structural calculations for racking attachment, roof loading and foundation design, engineered to the specific site.
Site-engineered load and attachment calculations
Engineered per site, not a generic load table
Wind, snow and seismic loading get calculated against the project's actual location and structure, since a generic load table is exactly what gets flagged in jurisdictions with stricter structural review.
Roof-mount and ground-mount both covered
Attachment point analysis for rooftop systems and pile or footing design for ground-mount projects are both in scope, engineered to the racking system actually being installed.
Stamped for the jurisdiction that requires it
PE stamping requirements vary by state and by project scale, and calculations here are delivered stamped where the specific jurisdiction requires it.
Pass structural review with the right stamp
Pass structural review the first time
Site-specific load calculations replace a generic table that draws scrutiny in stricter jurisdictions.
Get the stamp the project actually needs
Stamping requirements get matched to the specific state and project scale before submission.
Interconnection Studies
Application support and technical review for utility interconnection, the single biggest schedule risk on most solar projects today.
Application support and pre-submission technical review
Application support built for a slow-moving queue
Median time from interconnection request to commercial operation now runs past five years in several regions, and most projects that enter a queue never reach commercial operation at all. Application support here focuses on submitting a complete, technically sound request the first time, since resubmissions cost queue position.
Technical review before the utility's own study
Load flow, short-circuit and voltage impact are reviewed internally before formal submission, catching a technical issue a utility's cluster study would otherwise flag months later.
Readiness screening against utility requirements
Screening checks a project's technical package against the specific utility's interconnection standard before submission, since requirements vary meaningfully between utilities and even between service territories.
Protect queue position, catch issues early
Avoid a resubmission that costs queue position
A technically complete first submission avoids restarting the clock on a multi-year queue.
See technical issues before the utility does
Internal review catches load flow or voltage problems before they surface in a formal cluster study months later.
BIM & 3D Visualizations
Building information modeling and 3D visualization that catches clash conditions between racking, conduit and structural members before installation.
Clash detection and stakeholder-ready models
Clash detection before the field finds it
Racking, conduit runs and structural members get modeled together so a physical conflict shows up on screen during design instead of as a change order once a crew is on the roof.
3D visualization for stakeholder review
Renderings give a client, an AHJ reviewer or a financing partner a clear look at the finished system before construction starts, which is often what moves a stalled approval forward.
Works for rooftop and ground-mount alike
Modeling scope adapts to the project type, whether that's a complex rooftop with multiple roof planes or a ground-mount site with tracker rows and civil infrastructure.
Fewer change orders, faster sign-off
Fewer field change orders
Structural and routing conflicts surface during design review, not during installation.
Faster stakeholder sign-off
Clear 3D visualization gives reviewers and financing partners what they need to approve a design without a back-and-forth.
Guides for your next decision
Your questions, answered.
What engineering deliverables does a typical solar project need before permitting?
Most projects need a site plan, single-line diagram, structural calculations, equipment specifications and datasheets, and often a shading and production analysis, with the exact set depending on the AHJ and project size. Larger or interconnecting projects add interconnection studies. Sunhub produces these to the standard an AHJ or utility actually checks against, which reduces permit rejections.
Does Sunhub's engineering team stamp drawings for every jurisdiction?
Stamping requires a professional engineer licensed in the state where the project is built, so coverage depends on jurisdiction rather than being automatic everywhere. Sunhub produces permit packages, single-line diagrams, and structural calculations to the standard reviewers check against and arranges the appropriate licensed stamp for the project's location. Confirm the specific state when scoping the work.
How fast can a permit package or single-line diagram turn around?
Turnaround depends on project size, complexity, and how complete the site and equipment information is at the start, so a straightforward single-line diagram moves faster than a full structural package. Sunhub's aim is to move projects through permitting and interconnection with fewer rejections, which usually beats the round-trip cost of a package that gets kicked back. Share the project scope for a firm estimate.
What does a complete solar permit package include?
A complete package typically includes the site plan, electrical single-line diagram, equipment specification sheets, structural details or attachment plans, and the code compliance documentation the AHJ requires. Sunhub builds the full package rather than a partial one, with NEC 2023 detail worked in from the start. Exact contents still depend on what the specific jurisdiction asks for.
How much do permit requirements vary between jurisdictions?
Requirements vary considerably between AHJs, from the exact drawings and structural detail expected to which code cycle is enforced and how submissions are formatted. A package that clears one jurisdiction can be redlined by another for reasons that have nothing to do with the design. That's why Sunhub builds each package to the specific AHJ reviewing it rather than a generic template.
More questions about these services
What's the typical turnaround for a permit pack draft?
Turnaround is kept predictable so you can plan a project schedule around it, though the exact timeline depends on system complexity and the jurisdiction's requirements. Sunhub scopes turnaround up front rather than leaving it open-ended. For a specific job, confirm the committed timeline when you submit the project details.
Why does a flat shading derate underestimate or overestimate real production?
A flat derate applies one loss percentage across the whole array, but real shading is uneven, it changes by hour and season and hits specific rows and modules differently. That can overstate output where a fixed derate is too generous, or understate it where obstructions are minor. Site-specific modeling captures the actual pattern, which is why it holds up against measured production far better.
What tools are used to model site-specific shading?
Site-specific shading is modeled with tools that build a 3D representation of the array and surrounding obstructions and simulate the sun's path across the year, using inputs from a site survey, drone or lidar capture, or on-site horizon measurements. Common industry platforms handle the yield simulation from that geometry. The output is an hourly production estimate that reflects real obstructions rather than an assumed loss.
Does shading analysis affect string design and inverter sizing?
Yes, and that is much of its value. Knowing which modules shade and when guides how strings are grouped, whether module-level electronics help, and how the array is sized to the inverter's MPPT windows. Feeding real shading patterns into the electrical design reduces mismatch losses and produces a system that performs closer to the modeled number.
What does a solar single-line diagram need to show for permitting?
A permitting SLD needs to show the full electrical path and the equipment on it: modules and their configuration, inverters, DC and AC disconnects, overcurrent protection, conductor and conduit sizing, grounding and bonding, and the point of interconnection. It also needs NEC-compliant labeling and equipment ratings a reviewer can check against code. Exact expectations vary by AHJ, so the drawing should carry the detail a local reviewer requires.
Do utilities require a different SLD format than the local AHJ?
Often they emphasize different things: the AHJ focuses on NEC compliance and safety equipment for the permit, while the utility interconnection engineer focuses on the point of common coupling, protection, and metering. A well-built SLD is drawn to satisfy both audiences on one drawing rather than forcing two separate versions. Confirm each party's specific requirements, since formats and detail levels vary.
Can an SLD be stamped for multiple jurisdictions?
A PE stamp certifies the engineering, but a professional engineer can only stamp work in states where they hold a valid license, so multi-jurisdiction coverage depends on the engineer's licensure. A single design can be stamped for several jurisdictions when the engineer is licensed in each and the drawing meets each one's requirements. Where a stamp is required, confirm the engineer's licensure matches the project location.
When does a solar project need a stamped structural calculation?
A stamped structural calculation is typically required when the AHJ needs proof the roof or foundation can carry the added solar load, which is common for ground mounts, older or marginal roofs, and most commercial jobs. Some residential roofs pass on prescriptive tables, but many jurisdictions still ask for a stamp. Sunhub provides calculations engineered to the specific site and stamped for the jurisdiction that requires it.
Does structural engineering differ between roof-mount and ground-mount systems?
Yes. Roof-mount analysis centers on attachment points, member capacity, and how the array loads the existing structure, while ground-mount work focuses on foundation design, pile embedment, and soil conditions. Both must handle site-specific wind, snow, and seismic demands. Sunhub covers roof-mount and ground-mount alike, engineered per site rather than from a generic load table.
What load factors get analyzed for racking attachment?
Analysis generally accounts for dead load, live load, wind uplift and pressure, snow load, and seismic demand, all set by the site's location and building code. The attachment itself is checked for pull-out and shear at each connection to the structure. These factors drive both the racking spacing and the fastener spec.
Why do interconnection queues take so long right now?
Queues are backed up because the volume of projects applying has outpaced the utilities' and grid operators' capacity to study them, and each project's study can depend on others ahead of it, so one withdrawal can force restudies down the line. Many regions are also moving to cluster study processes to work through the backlog, which adds coordination time. The result is that interconnection is now the single biggest schedule risk on most projects.
What technical review happens during an interconnection study?
An interconnection study reviews how the project affects the grid at the point of connection, typically screening for thermal loading, voltage and power quality, protection coordination, and short-circuit contribution, and flags any upgrades the utility may require. Reviewing these before submission catches issues the utility would otherwise find, which is where resubmissions and lost queue position come from. Sunhub's readiness screening checks the application against utility requirements ahead of the utility's own study.
Can interconnection application support speed up queue position?
Application support does not let you jump the queue, but it protects the position you have by getting the submission complete and technically correct the first time, avoiding the deficiencies and resubmissions that cost queue slots. Screening against utility requirements before filing is where the real schedule savings come from. The aim is to keep the project moving rather than losing months to a rejected application.
What is clash detection and why does it matter for solar design?
Clash detection uses a 3D model to find where components physically conflict, such as racking crossing a conduit run or a structural member sitting where a rail needs to go, before anyone is on site. Catching those conflicts in the model avoids field change orders, rework, and schedule slips that are far more expensive to fix once material is installed.
Does BIM modeling work for both rooftop and ground-mount projects?
Yes. BIM applies to rooftop and ground-mount alike, modeling racking, conduit, and structural interfaces in either context. On rooftops it resolves conflicts with existing structure and equipment, while on ground-mount it coordinates racking, foundations, and civil elements. The value in both cases is finding the clash in the model instead of in the field.
What deliverables come out of a BIM engagement?
Typical deliverables include a coordinated 3D model, a clash detection report identifying and resolving conflicts, and visualizations for stakeholder review and sign-off. Depending on scope, the model can also feed coordinated construction drawings and quantity information. The practical output is fewer field surprises and faster approvals from the parties reviewing the design.
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