How to read a solar site plan

The site plan is the sheet a reviewer opens first to answer a simple question: where does this system physically sit on the property, and does the layout obey the setback and access rules? It is a scaled, top-down map of the lot, the building, the roof, and the array. Get it wrong — missing a north arrow, no dimensions, an array drawn over a required fire pathway — and the whole packet stalls. This is the visual companion to the solar one-line diagram, and together they carry most of a residential review.

What the site plan must show

A residential solar site plan is a plot plan with the PV system added on top. Every element below exists so a reviewer can confirm the design without visiting the site.

How a reviewer reads it

A plan checker works the sheet in a predictable order. First they find the north arrow and the scale, because nothing else on the page means anything without them. Then they locate the property lines and the building footprint to confirm the structure is where the address says it is. Next comes the array outline on each roof plane — they count modules, check that the outline stays on solid roof, and confirm it clears vents, chimneys, and skylights.

The most scrutinized part is fire access. Under the International Fire Code (IFC 605, the successor to the 2018 IFC 1204 provisions), most residential roofs require clear pathways and setbacks so firefighters can move and ventilate. On a typical dwelling that means an approximately 3-foot setback from the ridge and clear pathways to roof planes, though hip roofs and small systems get exceptions. The reviewer measures these clearances directly off your dimensioned drawing, which is why the setback callouts and the scale have to be honest. Our guide to fire setbacks for rooftop solar under IFC 605 breaks down the pathway rules.

The array outline and roof planes

Each roof plane that carries modules gets its own labeled outline with the module count and orientation (portrait or landscape). The reviewer uses the outline plus the scale to confirm the array fits the plane with the required setbacks left over — not just that the modules exist, but that the ridge, eave, rake, and any valley clearances survive after the array is placed. Dimension lines from the array edge to the nearest ridge and eave are what let them check this in seconds. A common rejection is an array outline that visually crowds the ridge with no dimension proving the setback.

Equipment locations and dimensions

The site plan also fixes the balance-of-system equipment on the ground: the main service panel, the production or utility meter, the inverter, and the AC disconnect the utility usually requires within sight of the meter. Reviewers check that a disconnect is present and reachable, and that its placement is consistent with the one-line diagram. Every meaningful distance — panel to disconnect, array to setback line, structure to property line — should carry a dimension. If it matters to code, it gets a number.

How aerial imagery is used as a base

Modern site plans almost always start from aerial or satellite imagery. The designer traces the roof edges, structures, and property lines over a georeferenced photo, which produces accurate roof geometry and true azimuths without a site visit. The imagery becomes the base layer; the array, dimensions, north arrow, and scale are drawn on top. The photo is a reference, not the deliverable — a reviewer still needs a scaled, dimensioned drawing, so imagery-only submittals that lack measurements get bounced. The free instant estimate tool uses aerial roof geometry to sketch a preliminary layout, and the design app turns that into a permit-grade site plan with the setbacks and dimensions in place.

Common site-plan corrections

The rejections here are rarely exotic — they are missing basics. No north arrow. No stated scale. An array outline with no setback dimensions. A disconnect shown on the one-line but absent from the site plan, or vice versa. Fire pathways drawn under the array. Because these are visual and measurable, they are also easy to catch before you submit. Reviewing your own site plan the way a checker does — arrow, scale, lines, array, setbacks, equipment, dimensions — heads off most of the reasons solar permits get rejected. For the full list of sheets a complete packet needs, see what is in a solar permit set, and explore a real teardown at the permit-set anatomy page.

The site plan is the one sheet that ties the electrical design to a physical roof. Draw it to scale, dimension everything that matters, respect the fire pathways, and give the reviewer nothing to measure that doesn't already check out.

Educational reference, reviewed 2026-07. A design aid, not a substitute for a licensed electrician or PE. Confirm the enforced NEC edition and local amendments with your AHJ.