This case study highlights a 20 kV grid-connected solar project in Iran featuring a 3150 kVA box substation. The project demonstrates how careful design, precise manufacturing, and rigorous testing of the substation ensure stable medium-voltage grid integration for utility-scale photovoltaic applications. From initial technical clarification to final delivery, the 3150 kVA box substation played a critical role in achieving reliable power conversion and long-term operational stability.
Project Overview
This project is a utility-scale, grid-connected solar power plant located in Iran. The photovoltaic system is designed to connect to the local medium-voltage grid at 20 kV, with a total installed DC capacity of approximately 5 MWp.
To support stable and reliable grid connection, the project is equipped with two 3150 kVA European-type box substations, providing sufficient transformer capacity and operational margin for long-term operation under varying load conditions.
Key Project Information
- Project Type: Ground-mounted solar power plant
- Location: Iran
- Grid Voltage: 20 kV
- PV Installed Capacity (DC): ~5.0 MWp
- Transformer Configuration: 2 × 3150 kVA European-type box substations
- Application: Medium-voltage grid-connected PV system
This case study presents how the project progressed from early-stage technical clarification to final manufacturing and testing, despite limited initial experience with high-voltage PV substation delivery.
Project Background and Challenges
The project represented a first-time high-voltage PV substation delivery for the supplier and involved several technical and communication challenges during the early stages.
From the client’s perspective, the main challenges included:
- Limited experience with 20 kV grid-connected PV systems
- Incomplete understanding of primary and secondary electrical systems
- Unclear technical requirements during early communication
- A tight delivery schedule, with potential constraints around the holiday period
At the same time, the supplier had not previously delivered a complete PV project involving medium-voltage transformers and box substations, which required rapid internal alignment and technical preparation.
Without timely clarification and coordinated technical support, these challenges could have led to design delays, mismatched expectations, or risks during manufacturing and grid connection.
Technical Solution and Communication Approach
System Configuration
European‑style box‑type substations integrate high‑voltage switchgear, transformer, and low‑voltage distribution into one modular enclosure, reducing installation time and improving safety. Learn more about European‑style box‑type substations
After a detailed review of the project requirements, the technical team proposed a solution based on two 3150 kVA European-style box substations, configured for 20 kV / 0.8 kV box substation solution operation and optimized for utility-scale photovoltaic applications.
The solution was designed to:
- Meet local grid-connection requirements
- Support stable operation under fluctuating PV output
- Provide adequate capacity margin between DC generation and AC conversion
- Simplify installation and on-site commissioning
The overall system architecture covered both primary electrical equipment (transformers, medium-voltage switchgear) and secondary systems (control, protection, and monitoring).
Technical Communication and Coordination
Due to gaps in early-stage requirement definition, a structured communication approach was implemented.
- Cross-department technical meetings were organized internally to align sales, engineering, and supply chain teams
- Online technical conferences were conducted with the client’s engineering team
- Key questions related to electrical topology, protection schemes, and control logic were clarified in real time
During a dedicated video conference lasting over one hour, engineers from both sides reviewed the entire electrical system, including:
- Primary wiring configuration
- Secondary control and protection logic
- Interface requirements for grid connection
This direct and transparent technical exchange significantly reduced uncertainty and helped the client gain confidence in the proposed solution.
Manufacturing and Quality Control
Following technical confirmation, the project entered the manufacturing phase. Since this was the first delivery involving medium-voltage transformers, the project team paid particular attention to supplier selection, quality control, and schedule management.
Factory Audit and Supplier Selection
- Multiple transformer manufacturers were evaluated
- Factory audits were conducted to assess production capability and quality systems
- A qualified manufacturer with experience in European-type box substations was selected
Design Optimization During Production
During the production process:
- Electrical drawings were continuously reviewed and optimized
- Technical details were refined to ensure compliance with project requirements
- Close coordination between engineers and the factory helped accelerate production without compromising quality
Despite the tight timeline, the project team successfully completed both 3150 kVA box substations within the planned schedule.
Testing and Final Inspection
Before delivery, the equipment underwent comprehensive testing, including:
- Routine transformer tests
- Functional checks of primary and secondary systems
- Verification of protection and control circuits
By early February, the testing team had successfully completed factory tests on both 20 kV European-type box substations and approved them for shipment.
Project Results and Value Delivered
The team successfully delivered the project, handling everything from initial technical clarification to completed manufacturing and testing, despite having limited prior experience with similar high-voltage PV applications.
Key outcomes included:
- Successful delivery of the first medium-voltage PV substation project
- Full compliance with 20 kV grid-connection requirements
- Clear and efficient communication between engineering teams
- Establishment of a repeatable delivery process for similar projects
From the client’s perspective, the project demonstrated that a supplier with strong technical coordination and execution capability can effectively manage complex PV substation requirements, even under time constraints.
Why This Project Matters
This project represents more than a single delivery. It demonstrates the ability to:
- Transition from zero experience to closed-loop project execution
- Coordinate sales, engineering, and supply chain teams efficiently
- Deliver European-type box substations for utility-scale PV applications
- Support overseas EPC and solar developers with reliable technical solutions
The experience gained through this project now serves as a solid reference for future 20 kV solar PV substation and medium-voltage transformer projects.
اتصل بنا
If you are planning a grid-connected solar power project and require a reliable supplier for box substations or medium-voltage transformers, our engineering team is ready to support your technical requirements.
Feel free to contact us to discuss your project in detail.