Design Package Compilation and Plan-Check Readiness
Objective. Students assemble a permit-ready residential PV design package—including site plan, single-line diagram, shade report, equipment schedule, and structural attachment notes—and present it in a structured peer review that replicates an AHJ plan-check, identifying and correcting at least 90% of seeded errors introduced by the instructor.
This lesson, its worked examples and its practice questions has not yet been verified by a licensed professional engineer or master tradesperson or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.
VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.
What a Permit-Ready PV Design Package Is
Before a residential PV system can be installed, the local Authority Having Jurisdiction (AHJ)—usually a city or county building department—must review and approve a design package. This review is called a plan check. A plan check confirms that the proposed system meets applicable electrical codes (primarily the National Electrical Code), building codes, fire codes, and any local amendments. A permit-ready package is one complete enough that the AHJ can approve it without requesting additional information. Incomplete packages are rejected and returned, costing the installer time and delaying the customer's project. Assembling a clean, organized package is therefore a core professional skill.
Standard Contents of a Residential PV Permit Package
Most AHJs expect the following documents, organized so the reviewer can move through them in a logical order:
Cover Sheet — Identifies the project address, property owner, installing contractor, license numbers, and the applicable code editions. Many jurisdictions supply their own cover-sheet form.
Site Plan — A dimensioned overhead drawing showing the property boundary, structure footprint, array location on the roof, required setbacks (fire access pathways), and compass orientation. Setback requirements vary by jurisdiction and are typically based on adopted fire codes; confirm local rules for each project.
Roof Plan / Array Layout — Shows module positions, row spacing, attachment point locations, and roof section dimensions. Labels should identify the modules by model number or reference the equipment schedule.
Single-Line Diagram (SLD) — An electrical schematic showing the complete circuit from modules through combiners (if any), inverter(s), AC disconnect, utility meter, and main service panel. The SLD must show conductor sizes and types, conduit types, overcurrent protection device (OCPD) ratings, grounding and bonding connections, and interconnection point. All labels must match the equipment schedule and datasheets.
Equipment Schedule — A table listing every major component: modules (manufacturer, model, rated power, Voc, Isc, temperature coefficients), inverter(s) (manufacturer, model, rated AC output, MPPT range), racking system, and disconnects. Include listing certifications (UL or equivalent) for each item.
Module and Inverter Datasheets — Manufacturer cut-sheets confirming the specifications used in your calculations. Highlight or annotate the values used on the SLD.
Production Estimate — A PVWatts or equivalent software report showing estimated annual kWh output, used to size the system against the customer's load. Include input assumptions (tilt, azimuth, system losses, location).
Structural Attachment Notes — A drawing or note sheet showing the roof construction type (rafter size and spacing, sheathing thickness), the attachment hardware selected, lag bolt diameter and embedment depth, and how the attachment meets the load requirements. If an engineered letter or stamped drawing is required by the AHJ, that goes here.
Calculations Summary — Shows string sizing math (Voc temperature correction, Vmp temperature correction, string current), conductor ampacity calculations, and OCPD sizing. This allows the plan checker to verify NEC compliance without reconstructing all your work.
Organizing the Package
Organization signals professionalism and speeds approval. Use a cover sheet as page 1, followed by a table of contents with page numbers. Tab dividers in a three-hole binder (or named folders in a digital submission) help reviewers navigate quickly. Number every page and label every drawing with the project address and revision date. If you revise any sheet after submission, update the revision block and resubmit only the changed sheets clearly marked as revisions.
How a Plan Check Works
The AHJ assigns a plans examiner who works through the package against a checklist derived from adopted codes and local amendments. Common deficiency notices include: missing conductor labels on the SLD, an OCPD rating that does not match the calculated value, setbacks not shown or dimensioned, missing or mismatched equipment datasheets, and structural notes that do not specify embedment depth. Each deficiency must be corrected and resubmitted before a permit is issued.
During peer review, you are acting as a plans examiner. Read critically, not charitably. A detail that seems obvious to you may not be documented—if it is not written on the drawing, the AHJ will assume it is absent.
Safety Points Relevant to the Design Package
Errors in a permit package can create real safety hazards in the field. Two areas deserve special attention:
- Electrical safety: An undersized conductor or wrong OCPD rating translates directly to fire risk. Verify every calculation. Confirm that rapid shutdown provisions are documented on the SLD if required by the adopted NEC edition.
- Structural safety: An incorrectly specified lag bolt embedment depth can lead to racking failure and fall hazards for installers and future maintenance workers. Never estimate; look up or calculate the required depth and put the specific value on the drawings.
During the debrief, be prepared to explain why you chose each conductor size, OCPD rating, and attachment specification—not just what the value is.
The Peer Review Memo
Write your plan-check memo as a numbered list of deficiencies. For each item, state: (1) where the error appears (sheet number, drawing title, or section), (2) what is wrong or missing, and (3) the applicable requirement that is not met. This format mirrors the official correction notices AHJs issue and gives the other team clear, actionable feedback.
After the Review: Correcting and Submitting
When you receive your peer review memo, work through every noted deficiency before final submission. Prioritize safety-critical errors—incorrect OCPD ratings, missing rapid shutdown notation, structural attachment omissions—above formatting issues. Your final package must contain no remaining safety-critical errors. Minor labeling or formatting issues found after submission can be addressed in a subsequent revision, but safety items cannot be deferred.
Key terms9
Materials: All documents from prior lessons, AHJ cover-sheet template (instructor-prepared based on common municipal format), plan-check checklist, three-hole binder or digital folder structure, oral debrief rubric
Check: Final submitted permit package and oral debrief; pass requires correct identification of at least 90% of seeded plan-check errors in peer package, and own final package free of any remaining safety-critical errors after revision. Oral debrief: student must answer at least 2 of 3 questions correctly to demonstrate design rationale. Pass = both criteria met.
Practice check8
Answer each question, then check it. Nothing is recorded; this is your own practice.
