The quote, bill of materials and installation plan for a rooftop solar project depend heavily on what you collect during the site survey. A detail missed on site comes back later as a wrong cable length, missing material on installation day or an argument with the customer. This article covers what to check on the roof, the supporting structure, the electrical installation, consumption, photos, safety and customer expectations, and ends with a checklist you can print and take with you.
Before you go
A survey does not start on site. Before the visit, ask the customer for the last 12 months of electricity bills, or at least bills from a few different seasons. Check the address on satellite imagery and note the rough roof shape and any tall buildings or trees nearby. Take a tape or laser measure, an inclinometer (or a phone app), a compass, a camera, personal protective equipment and a blank survey form.
Roof information
Roof type and condition
Clay tile, trapezoidal metal sheet, sandwich panel, membrane-covered flat roof and concrete terraces each need different fixings. Note the age and condition of the covering: broken tiles, rusted sheets, leaking spots or a covering due for replacement should be dealt with before the modules go on. Modules stay on the roof for well over twenty years, so mounting them on a worn covering may mean taking them down and reinstalling them later.
Orientation, tilt and usable area
Measure the orientation (south, south-east, east and so on) and tilt of each roof face separately. When estimating usable area, allow for edge setbacks, maintenance walkways and clearances around obstacles. The gap between gross roof area and the net area that can actually take modules can be significant.
Obstacles and shading sources
Record chimneys, vents, antennas, AC outdoor units, skylights and parapet walls with their positions and heights. Neighbouring buildings, trees and poles are shading sources too; note their approximate heights and distances from the roof. We explain the effect of shading on yield in our shading analysis article.
Access
How you reach the roof, how material will be carried up and whether a crane or scaffolding is needed all affect installation cost directly. Note the width of the building entrance, stairs, roof hatch and vehicle access.
Structural notes
No structural calculation is done during the survey, but you do collect what the person doing the structural review will need: the type of roof structure (timber trusses, steel purlins, reinforced concrete), purlin or rafter spacing, member sizes where visible, visible damage such as sagging or cracks, and the approximate age of the building. On flat roofs, the build-up of insulation under the covering matters when deciding between a ballasted and an anchored system.
Electrical installation
Main panel and meter
Photograph the main distribution panel, the free space inside it, the rating of the main breaker and existing protection devices. Note the meter type, serial number and location, as these may be requested in the grid application. Confirm whether the supply is single-phase or three-phase and check the account details against the bill.
Grounding
Check whether an earthing system exists and what condition it is in. Testing and, if needed, upgrading the earthing affects project scope and cost; knowing this at survey stage keeps the quote complete.
Cable routes and distances
Walk the DC cable route from the modules to the inverter location and the AC route from the inverter to the main panel, step by step. Note which wall, shaft or trunking the cable will follow, how many metres it is and how many bends it takes. The difference between the straight-line distance and the real route is often larger than expected.
Inverter location
The inverter should go somewhere cool and ventilated, out of direct rain and prolonged direct sun, and easy to reach for maintenance. Check the wall's load capacity, the clearances around the unit and internet access (Wi-Fi or cable for monitoring). If the customer wants storage, the battery needs its own space.
Consumption information
From the bills, extract monthly consumption, the unit price and the contracted capacity. The daily consumption pattern matters as much as the annual total: a business that runs during the day and a household that consumes mostly in the evening will have very different self-consumption ratios even with the same annual usage. Ask about working hours, summer and winter differences, high-power loads such as air conditioning or heat pumps, and planned additions such as EV charging. We explain why this matters in our article on self-consumption and net metering.
Photos to take
- The building from all four sides and the roof access point
- A wide shot of each roof face and a view looking south
- Close-ups of the roof covering and any damaged areas
- The roof structure, where visible (trusses, purlins, beams)
- Obstacles and surrounding shading sources
- The main panel (cover open and closed), the meter and its label
- The planned inverter location and key points along the cable route
- The earthing connection point
Keep location tagging on and add a short note to each photo describing what it shows. The person doing the design in the office may never have seen the site; well-labelled photos save you a second visit.
Safety
Before going onto the roof, assess whether the covering can be walked on; sandwich panels and fragile rooflights are a serious fall risk. Note anchor points for harnesses, parapet height and whether a lifeline is needed. Postpone the roof inspection in wet, windy or snowy weather. These notes also feed into the installation crew's safety plan.
Customer expectations
The survey is your best chance to talk to the customer face to face. Clarify how much they expect to save on their bill, which areas they prefer or refuse for modules, any aesthetic concerns, whether they want storage, their budget range and when they want the installation. Writing the customer's requests on the form prevents "but I told you" discussions at quote stage.
Printable checklist
| Area | Check | Notes |
|---|---|---|
| Roof | Type, age and condition of covering | |
| Roof | Orientation and tilt of each face | |
| Roof | Gross and usable area | |
| Roof | Obstacles and their heights | |
| Roof | Surrounding shading sources and distances | |
| Roof | Access, crane or scaffolding needs | |
| Structure | Structure type, spacing, visible damage | |
| Electrical | Main panel location, free space, main breaker | |
| Electrical | Meter type, serial number, phase | |
| Electrical | Earthing present and condition | |
| Electrical | DC cable distance (m) | |
| Electrical | AC cable distance (m) | |
| Electrical | Inverter location, ventilation, internet | |
| Consumption | 12 months of bills, unit price, contracted capacity | |
| Consumption | Daily usage pattern, new loads | |
| Photos | Facades, roof, panel, meter, cable route | |
| Safety | Fragile surfaces, anchor points, parapet | |
| Customer | Requested capacity, module/inverter preference, storage, budget, timing |
After the survey
Completing the survey report on the same day means the information is written down while it is fresh. The report goes to the design and quoting team and, where needed, to the engineer doing the structural review. Logging the survey date and surveyor on the project record also makes the later stages easier to follow, which we cover in our 13-stage project tracking article.
Site surveys with PVAGE
In PVAGE, surveys follow a standard site form. Alongside roof, electrical and consumption information, the form records the requested capacity, module and inverter preference, storage request and DC and AC cable distances. Photos taken on site and the GPS location are attached to the survey.
Survey reports go through an approve or reject flow, and from an approved report you can move straight to "Prepare Quote" or "Plan Installation". Information collected on site reaches the design, quoting and scheduling teams without being retyped. See the site survey feature page for details.