Solar Carport Design: Tilt, Orientation and Height Limits

The short answer

Three design choices move a solar carport's output: tilt, orientation and shading. For a south-facing canopy, PVGIS shows each step from 5° to 20° of tilt adding roughly 3–4% to annual output at all four UK sites tested, and a 35° tilt adding about 10–11% over 10°. An east-west canopy at 10° yields roughly 8–9% less than a south-facing one at the same tilt. The catch is height: in England the permitted-development route for car park canopies stops at 4 metres, so tilt, span and the clearance under the low edge have to fit under that ceiling together.

Annual yield by tilt and orientation (PVGIS)

PVGIS v5.3, SARAH3 data, 14% system losses, 1 kWp, run on 20 October 2026. Figures are kWh per kWp per year. South means due south; east-west is the average of an east-facing and a west-facing plane at 10°.

Read it as a trade. A low tilt costs a few per cent of yield but keeps the canopy low, light and quiet in the wind. A steeper tilt gains yield but needs more height across the same span. An east-west layout gives up about 8–9% of annual yield against south-facing, and in return the output curve is flatter across the day, which can suit a site whose demand is spread through the working day. Whether that trade pays is a modelling question for the specific load.

Winter share of summer output

December output as a share of June output, at a 10° tilt:

A canopy with a low tilt produces a small share of its summer output in December, and the share falls further for east-west and further north. That matters for sites whose load peaks in winter and for any lighting or EV load you expect the array to offset in the dark months. See also how much power a solar carport generates per bay.

The 4 metre ceiling: tilt, span and clearance

Class OA of the England GPDO permits a solar canopy on non-domestic off-street parking only if no part is more than 4 metres above ground level. For a single-slope canopy the high edge sits at the low-edge clearance plus the span times the tangent of the tilt, plus the depth of the structure. Ignoring structure depth, the longest span that fits under 4 metres is shown below for three illustrative low-edge clearances; real spans are shorter once beams and panels are counted.

Worked example: a single-slope canopy spanning two rows of 4.8 m bays nose to nose (9.6 m) rises about 1.7 m at 10° and about 3.5 m at 20°. At 20° that leaves almost no room for clearance under the low edge within 4 metres, so a steep tilt over a wide span tends to need a taller structure and therefore a full planning application rather than the permitted-development route. Set the clearance from the tallest vehicle that must pass underneath, then see what tilt the ceiling leaves you. The conditions and the exclusions are in Class OA in brief.

Fitting the column grid to the bays

Column positions should follow the bay lines so that columns do not intrude into a space. Local authorities set their own bay sizes. Surrey County Council's guidance, for example, gives a standard perpendicular bay of 2.4 m by 4.8 m, an off-street bay within a property's curtilage of 2.6 m by 4.8 m, and a perpendicular disabled bay of 2.8 m by 4.8 m with an additional 1.2 m between two disabled bays. Use the dimensions your own local authority and site layout require, then choose a column spacing that is a whole number of bay widths. The structural side is covered in frame and structure: steel and wind loading and ground and weight.

A short design brief

1. Target yield and layout: tilt and orientation, with the PVGIS figure for your site.
2. Clearance: the tallest vehicle that must pass under the low edge, and the resulting maximum span within your height ceiling.
3. Column grid: a whole number of bay widths, checked against the local bay standard.
4. Drainage: Class OA requires run-off from a canopy over a permeable surface to be directed to a permeable area within the parking area.
5. Glare and appearance: prior approval considers siting, design and appearance, in particular glare on neighbouring occupiers.
6. EV and lighting provision: where charging and lighting will run, so the structure and the cabling route allow for them (see solar car park lighting).
7. Completion and removal: works under Class OA must be completed within three years of the determination and the canopy removed when no longer needed.

For specification and pricing, see solar carports, the car park solar panels guide and the cost guide.

Frequently asked questions

Sources and last checked

Last checked 20 October 2026.

• PVGIS v5.3 (SARAH3), European Commission JRC: 1 kWp, 14% losses, tilt and azimuth as stated; run 20 October 2026 (data saved in research/pvgis-2026-10-20.json)
• legislation.gov.uk: GPDO 2015 Schedule 2 Part 14 Class OA
• Surrey County Council: Parking space dimensions (Healthy Streets guidance, section 10.4)
• Span table: trigonometry from the 4 m ceiling, (4.0 minus clearance) divided by tan(tilt); structure depth ignored

Related reading: solar panels over parking bays · school car park canopies · solar canopy specification and types.