IN Brief:
- More than 1MW of solar capacity is being installed across eight canopies covering about 243 parking bays at Scottish Water's Stepps headquarters.
- Will Rudd reused much of the site's existing drainage infrastructure, limiting new underground works while integrating the canopies into an operational car park.
- The installation is expected to generate around 1GWh annually and supply roughly one third of the headquarters' electricity demand.
Civil and structural engineering consultancy Will Rudd has supported delivery of a solar carport installation at Scottish Water’s headquarters in Stepps, Glasgow, where more than 1MW of photovoltaic capacity is being installed above an operational car park.
The scheme spans eight canopies covering approximately 243 parking bays and incorporates around 2,250 solar panels. Once operational, the installation is expected to generate around 1GWh of electricity each year, equivalent to roughly one third of the site’s annual power requirement, with an estimated saving of about 160 tonnes of carbon dioxide equivalent annually.
Will Rudd was appointed by OCS to provide civil and structural engineering services for the project. Its work included reviewing existing information, carrying out site inspections and surveys, designing foundations and substructures, developing the drainage strategy, completing swept-path analysis for vehicle movements and providing structural engineering certification for the third-party canopy structures.
The project has required those elements to be introduced without treating the existing car park as a blank site. Scottish Water’s headquarters remained an active workplace, leaving the engineering team to accommodate staff access, vehicle circulation, existing utilities and surface-water flows while making space for a new layer of energy infrastructure above the parking area.
An early drainage concept envisaged a more extensive underground solution. Detailed assessment of site levels and existing drainage showed that much of the installed network could instead be retained and incorporated into the final design, alongside sustainable drainage features. Only one new drainage connection was required to serve the proposed glass-reinforced polyester switch room.
That change reduced excavation and the amount of new below-ground drainage work needed around the canopies. It also limited intervention in an operational car park, where every additional trench introduces temporary access constraints, utility risks and reinstatement work. The structural design had to deal with the corresponding loading and foundation requirements while preserving practical vehicle movements below the new arrays.
The current installation represents a progression from the £2.4m solar-carport project announced by Scottish Water in 2025. At that stage, the utility expected the 2,250 bifacial panels to generate around 0.87GWh a year and meet approximately 34% of the headquarters’ electricity demand. The latest engineering update puts expected generation at around 1GWh a year while retaining the estimate of roughly 160 tonnes of annual carbon savings.
The updated generation figure sits above Scottish Water’s original estimate, but the construction challenge is defined by the interface between the solar equipment and the existing civil infrastructure. The canopies occupy the same working environment as lighting columns, drainage runs, buried services, pedestrian routes and vehicle swept paths, so foundations and structures have had to be designed around those constraints rather than in isolation.
That makes the Stepps project a building-services and civils exercise as much as a photovoltaic installation. The engineering scope extended from the canopy foundations down to drainage and across to traffic movement, while the electrical system introduces a switch-room connection and the interfaces required to bring generation into the headquarters’ power system.
The scheme also adds another generation asset to Scottish Water’s portfolio of solar installations at operational water and wastewater sites. The organisation has set a net-zero target for 2040, and its existing estate creates opportunities to use occupied land and built assets for electricity generation without requiring separate greenfield sites.
Car parks offer that dual use of space, but the structure still has to work around circulation, drainage and safe access during installation. At Stepps, retaining much of the existing drainage network has reduced the amount of new underground work required while the car park continues to support its original function.
Will Rudd is also working with OCS on other energy-related programmes, including structural assessments supporting battery storage installations and feasibility work for solar PV on public-sector buildings. The Stepps scheme demonstrates the recurring practical issue behind those programmes: renewable equipment rarely arrives on an unconstrained site, and much of the delivery risk sits in the interfaces with what is already there.
With the canopies and panels now forming part of the existing headquarters rather than a standalone energy site, the project provides a useful example of how structural, drainage and access design can determine whether additional generation capacity can be installed without disproportionate disruption. The final measure will be operational performance once the system is fully commissioned against the current expectation of around 1GWh of annual output.
