How Many Solar Panels Fit Over One Parking Bay?

Why bay count beats floor area

A canopy frame lands between bays, not across them, so the usable array follows the parking layout rather than the painted area of the car park. The working figure for a commercial canopy is about 1.5 kWp per standard bay, which at current module ratings is roughly three to four panels. Floor-area estimates routinely overstate the array because they ignore the columns, the circulation aisles and the setbacks the structure needs.

What that generates, by where you are

Canopies sit at a shallow pitch, around 10 degrees, because a steeper tilt costs headroom and adds wind load — so the rooftop 35-degree yield figure does not apply. At 10 degrees facing south, PVGIS gives roughly 920 kWh/kWp in London, 946 in Cardiff, 807 in Manchester and 772 in Glasgow. A 200-bay car park at 1.5 kWp per bay is about 300 kWp, generating roughly 276,000 kWh a year in London and about 232,000 in Glasgow.

The number that actually decides the business case

Self-consumed generation is worth the full retail electricity rate; exported generation earns the Smart Export Guarantee rate, which is lower. So the question is not how many panels fit, it is how many the site can use during daylight. A car park attached to a building with a weekday daytime load — a supermarket, a hospital, an office estate — self-consumes most of what it generates. A car park that empties at 18:00 next to a building that does the same exports the surplus at a lower rate. Size against the load curve, not the roof area — and read solar carport cost for what the resulting array costs per kWp.

Where the arithmetic breaks

Three common errors: using a 35-degree rooftop yield for a 10-degree canopy, which overstates generation by a tenth or more; assuming the full bay count when the DNO imposes an export limit, which caps what the array can do regardless of its size; and quoting G98 for the connection, when G98 stops at 16 A per phase — about 3.68 kW per phase — so every car park array is a G99 application. Full detail on sizing and specification sits on the car park solar panels page.

Related reading: how the AIA applies to a carport · bifacial car park panels · school and university car parks.