Two canopy quotes for the same car park can differ by a third and still not be comparable. One assumes pad foundations on good ground, the other piles. One prices a yield from a generic figure, the other from a site model. One includes the grid application and one lists it as an extra. The tender document decides whether you receive comparable prices or a collection of different products.
This checklist is for estates, facilities and finance teams writing or reviewing a canopy specification. It follows the order of our solar canopy design page, and the figures it quotes come from there and from our cost guide.
1. Site and use
State, in plain terms:
- The bays to be covered, shown on a marked-up plan, and the number of spaces.
- The vehicles that use each bay, and the clear height they need. Clearance is the dimension that most changes price; see our note on vans, HGVs and the 4 m planning cap.
- The structure type you will accept or want priced: mono-pitch, T-frame or cantilever. Asking for two types on the same layout shows the price step.
- What must stay clear: delivery routes, accessible bays, fire access, existing lighting, drainage and services.
2. Structural design
Ask the tenderer to state the basis, not just the result:
- Wind loading to BS EN 1991-1-4 for the site location and exposure.
- Snow loading to BS EN 1991-1-3 for the geographic zone.
- The Eurocode set used for the steelwork and foundations, and confirmation that the design is signed off by a chartered structural engineer.
- Corrosion protection: hot-dip galvanising to BS EN ISO 1461 is the usual reference.
- Execution class for the steel fabrication, so you know which fabrication standard the supplier is working to.
- Elevations of all four sides with dimensions and eaves heights, so the maximum height of any part of the structure can be checked.
3. Foundations and ground
Foundations are the largest swing in the budget. Our cost page puts pad foundations on competent ground at about £700 to £1,100 per column and piles on made ground or over services at £1,800 to £3,500 per column. A tender should therefore say:
- Whether a ground investigation has been done and, if not, that the price carries a provisional sum for foundations, not a fixed number.
- The foundation type assumed and what happens to the price if the ground differs.
- Who is responsible for service detection before piling.
A fixed foundation price offered before anyone has looked at the ground is a guess dressed as a figure.
4. Generation and yield
- The system size in kWp and the panel count.
- The modelling method. A proper yield study is run in a tool such as PVSyst with typical meteorological year data for the site, and gives P50 and P90 estimates. The P90 figure belongs in the financial model.
- The assumed tilt, orientation and shading, and the degradation rate.
- The inverter arrangement and any monitoring.
Without the assumptions, a kWh figure cannot be compared with another bidder’s.
5. Grid connection
State who applies and who pays:
- Whether the tender includes the G99 application and the DNO connection works, or only the application.
- The export limit, if any, and its effect on the size.
- The expected timeline. Connection is often the longest item in the programme; see the G99 timeline guide.
6. Consent
- Which route the tenderer expects: permitted development under Class OA in England, Class 9M in Scotland or a full planning application. Our planning guide sets these out.
- Who prepares and pays for the application, and what happens if it is refused.
- Whether a glare statement is included; see what prior approval asks for.
7. Commercials
- A price split into structure, panels and electrical, foundations, grid, consent and commissioning, so you can compare line by line.
- Payment milestones tied to completed work.
- Warranty terms for the structure, the panels and the inverters, and who holds each.
- Operations and maintenance scope and price, if offered.
- How the price is funded: purchase, finance, lease or a power purchase agreement. The route changes the tax position, covered on our capital allowances note.
8. A short scoring sheet
Once the tenders arrive, score each on the same six lines: price per kWp on the same scope, price per space covered, quality of the structural basis, the yield assumptions, the grid and consent responsibilities, and the warranty. A low price that leaves the grid, the consent or the ground investigation to you is not low.
Starting the brief
If you would like help turning a car park into a specification you can tender, request a free feasibility assessment. We reply by email with indicative capacity, the likely consent route and the main cost drivers for the site. For the overview of what a solar panel canopy is and how it is built, start with that page.
Standards and figures checked against our design and cost pages on 18 October 2026. Confirm current versions of standards with your structural engineer.