Solar Site Survey Checklist: Roof, Attic, Service Panel and Meter, Walked in Order

A solar site survey is the visit between a signed contract and a final design: someone goes to the home, gets on the roof, into the attic and in front of the electrical panel, and records everything the designer and the installer will need. A good survey means the design is right first time and the crew arrives with the right parts. A rushed one means a redesign, a change order the customer didn't expect, or a second visit nobody is paid for.

This is the survey in the order you'd walk it, and what each stop decides.

1. From the street: the house and the shade

Before the ladder comes off the truck.

• Photos of every side of the house, including the roof planes you'll be working on
• Trees and buildings that could shade the array, on every side, not just the south (or north, south of the equator)
• Which way each roof plane faces, roughly, to check against the satellite view
• Access: where a ladder can go, where materials can be staged, overhead lines near the roof edge
• HOA or historic district signs: worth asking the customer about now

What it decides: whether the satellite-based proposal still holds. A tree that's grown since the imagery was taken can move a whole array.

2. The roof, plane by plane

Record each roof plane separately. A design is built plane by plane, and a survey that lumps them together forces the designer to guess.

• Covering: asphalt shingle, tile, metal, flat membrane. Each needs different attachments.
• Age and condition: an array lasts 25 years or more. A roof with five years left will have to come off with the panels on it. If the roof is near the end of its life, flag it now.
• Layers: more than one layer of shingles affects attachment and weight.
• Pitch and orientation of each plane
• Obstructions: vents, skylights, chimneys, satellite dishes, and the space they take out of the usable area
• Soft spots: walk the roof (safely) and feel for deck that gives underfoot
• Fire setbacks: note ridges, hips and edges, since local fire rules often require clear paths

What it decides: how many panels fit where, and which attachment system the crew brings.

3. The attic

The roof tells you the surface. The attic tells you what holds it up.

• Rafter or truss: size, spacing and direction, measured
• Decking: plank or sheet, and its thickness where you can see it
• Signs of trouble: sagging, cracked rafters, water stains, rot, past repairs
• Access for attachments: is there room to reach the rafters where the array will go?
• Conduit route: where a run from the roof to the panel could go

What it decides: whether the roof can carry the array as designed, or needs an engineer's review, and where the wiring will run.

4. The main service panel

This is the stop that causes the most redesigns.

• Photos: the panel closed, the panel open with the dead front on, the label, the main breaker, and the busbar rating where it's marked
• Main breaker size and busbar rating
• Spare spaces for a solar breaker
• Panel make, model and condition: some older panels are flagged by utilities and insurers and are commonly replaced before solar goes on
• Subpanels and where they feed from

What it decides: whether the system can connect at the existing panel, or needs a main breaker derate, a supply-side connection or a panel upgrade. Many installers check the panel against what's widely called the 120% rule for back-fed breakers. Getting this wrong on the survey is the classic surprise change order.

5. The meter and utility equipment

• Meter location, type and number
• Clearances around the meter, and space for any equipment the utility or local code requires nearby
• Existing solar, generator or battery on site
• Service entrance: overhead or underground

What it decides: the interconnection path and where the disconnect and any batteries can go.

The five things surveys most often miss

1. The roof's remaining life. The proposal assumed the roof was fine. Six months after installation, it needs replacing, and the panels have to come off.

2. The panel photos. A blurry label or a missing busbar rating means a second visit, or a design built on a guess.

3. Rafter spacing and size. Estimated from the outside, then found to be different in the attic on install day.

4. Shading from the side. The survey looked at the trees to the south, but the neighbour's oak to the west shades the array every afternoon.

5. The conduit route. Nobody worked out how the wire gets from the roof to the panel until the crew was on site.

Doing it on the roof

Surveys happen on a roof pitch, in an attic with a flashlight in one hand, and kneeling in front of a panel. Notes on a clipboard get written up in the truck from memory, and that's where details go missing.

Speak while you walk, and the document writes itself. Say what you see at each stop — "South plane, composition shingle, one layer, about eight years old, good condition. Vent pipe two feet from the ridge, photo. Attic: 2x6 rafters at 24 inches, no sagging. Panel: 200-amp main, 200-amp bus, two spaces free, photo of the label." — and the survey is written and photographed, plane by plane, before you've climbed down.

Related

• Solar site survey: the free template, plane by plane
• Solar installation checklist: QC and commissioning after the install
• Solar site assessment report for installers: what the customer-facing assessment covers
• Roofing inspection report: when the roof needs a proper look first

Frequently asked questions

What is a solar site survey? A visit to the home before final design to record the roof, attic structure, electrical service, meter, shading and access, so the system can be designed and installed correctly the first time.

What should a solar site survey checklist include? Photos of the house and shading, each roof plane's covering, age, condition, pitch, orientation and obstructions, attic framing size and spacing, the main service panel's breaker and busbar ratings with photos, spare spaces, the meter and utility equipment, and the route for conduit.

How long does a solar site survey take? Commonly one to two hours for a typical home, longer for complex roofs or older electrical services.

Why does the main service panel matter so much? It decides whether the system can connect at the existing panel or needs an upgrade, derate or a different connection method. Missing or unclear panel information is one of the commonest causes of redesigns and change orders.

Should the roof be replaced before solar? If the roof is near the end of its life, often yes. Panels usually last 25 years or more, and removing and reinstalling an array to replace a roof later adds significant cost.

Who does the solar site survey? Usually a site surveyor or technician from the installer, sometimes the installer's crew lead. The designer uses the survey to finalise the layout and electrical plan.