01Project overview & context
Overview
Project summary
SgurrEnergy was appointed by Kalpataru to provide detailed design engineering for the Ad Darb utility-scale solar PV project in Saudi Arabia. The assignment covers PV engineering through the 33 kV collector system, energy yield assessment, technical specifications and the 132 kV plant-evacuation system. SgurrEnergy applied hourly generation and operating-voltage data to optimise string sizing, used CYMCAP analysis to optimise MV cable sizing and trench arrangements, and evaluated layout alternatives to reduce robotic-cleaning requirements and balance DC and MV cable lengths.
Project context
The Ad Darb development is a large utility-scale solar PV project in the Kingdom of Saudi Arabia. The electrical design extends through the 33 kV collector system and interfaces with a 132 kV plant-evacuation system.
The engagement requires coordinated optimisation of PV strings, DC and MV cabling, trench configurations, robotic-cleaning layouts and MV station locations. The engineering objective is to meet project specifications while reducing equipment quantities, cable lengths, installation complexity, electrical losses and overall project cost.
Client objectives
- Develop a coordinated engineering package through the 33 kV collector system.
- Optimise string sizing using hourly generation and operating-voltage data.
- Optimise MV cable sizing and installation arrangements while satisfying project requirements.
- Reduce robotic-cleaning equipment requirements through layout optimisation.
- Optimise MV station locations to balance DC and MV cable lengths, system losses and project cost.
Key challenges & considerations
String Sizing under Actual Operating Conditions
Conventional string sizing based only on standard test conditions can underuse the permissible inverter operating envelope, so the design considered hourly generation and operating-voltage data.
MV Cable and Trench Optimisation
Cable ampacity depends on spacing, trench geometry, grouping and backfill thermal properties — multiple configurations were modelled in CYMCAP to optimise cable size and arrangement.
Robotic-Cleaning Layout
The plant layout needed to support robotic module cleaning with the fewest practical robotic units, requiring coordinated table and access planning.
MV Station Siting and Cable Balance
MV station locations affect DC and MV cable quantities, voltage drop, losses and cost — several layout alternatives were compared to find the most efficient overall balance.
02Engineering scope & delivery
Role & engineering approach
Independent engineering role
SgurrEnergy’s role
SgurrEnergy is providing detailed engineering for the solar PV plant through the 33 kV collector system, together with energy yield assessment, preparation of technical specifications and engineering of the 132 kV plant-evacuation system.
The assignment combines electrical design, plant-layout optimisation and multidisciplinary interface management. SgurrEnergy is also coordinating technical review comments from the client and Owner’s Engineer, supporting timely resolution of engineering interfaces and technical issues.
Our engineering approach
SgurrEnergy applied a data-led optimisation approach rather than relying only on conventional conservative assumptions. Hourly generation and operating-voltage data informed string sizing. CYMCAP modelling was used to test MV cable performance across alternative trench configurations, cable spacings and backfill materials. Layout alternatives were then evaluated against robotic-cleaning requirements and the combined effect of DC and MV cable lengths.
These studies were integrated with the project specifications and the 33 kV collector and 132 kV evacuation requirements. Technical comments and multidisciplinary interfaces were tracked through closure so that optimisation decisions remained coordinated, compliant and implementable.
Scope of services & deliverables
Design Basis and Engineering Coordination
- Development and coordination of the detailed engineering basis and project design inputs.
- Preparation of technical specifications.
- Coordination of multidisciplinary engineering interfaces.
- Management and closure of technical review comments from the client and Owner’s Engineer.
DC and AC Electrical Systems
- Detailed PV and DC-system engineering.
- String sizing based on hourly generation and actual operating-voltage data.
- DC cable sizing, routing and layout coordination.
- Energy yield assessment and design-input coordination.
Collection and Evacuation Infrastructure
- Detailed engineering of the 33 kV collector system.
- CYMCAP-based MV cable sizing and ampacity assessment.
- Evaluation of trench configurations, cable spacing and backfill materials.
- Engineering and interface coordination for the 132 kV plant-evacuation system.
Layout and Station Optimisation
- Plant-layout optimisation to reduce the required number of robotic-cleaning units.
- Assessment of multiple MV station location alternatives.
- Balancing of DC and MV cable lengths and associated electrical losses.
- Coordination of layout, cable routing, installation and operational interfaces.
Technical Coordination and Issue Closure
- Resolution of technical review comments.
- Coordination with client, Owner’s Engineer and multidisciplinary teams.
- Tracking and closure of engineering interfaces.
- Timely resolution of technical issues affecting design progression.
Project configuration
- Collector system up to 33 kV; plant evacuation at 132 kV.
- Cable analysis performed using CYMCAP.
- Robotic cleaning considered in layout optimisation.
03Value & outcome
Reduced String Quantity
Operating-voltage-based string optimisation reduced string quantity compared with the conventional sizing approach, supporting further optimisation of mounting-system quantities, balance-of-system components and overall project cost.
Optimised MV Cable Design
CYMCAP analysis supported optimisation of MV cable sizing to 400 sq.mm through evaluation of trench arrangements, non-standard cable spacing and backfill materials, while maintaining project-specification compliance.
Reduced Robotic-Cleaning Requirements
Layout optimisation reduced the number of robotic-cleaning units required, supporting lower equipment quantities and simpler operations.
Balanced Cabling and Lower Losses
Alternative MV station locations were compared to balance DC and MV cable lengths, reduce system losses and improve overall design and installation efficiency.
Project outcome
SgurrEnergy’s detailed engineering approach has combined project-compliant design with data-led optimisation across string sizing, MV cabling, plant layout and MV station siting. The ongoing engagement has produced a coordinated engineering package through the 33 kV collector system and supports the 132 kV evacuation interface.
Why SgurrEnergy
- Independent engineering judgement, separate from EPC, OEM and equipment-supply interests.
- In-house multidisciplinary capability across solar, electrical, civil, structural, grid and transmission engineering.
- Experience coordinating complex utility-scale renewable energy projects and multiple engineering packages.
- Structured technical governance, document review and comment-closure processes.