Photovoltaic box-type substation (referred to as photovoltaic box transformer) is an outdoor pre-assembled complete set of power transformation equipment specially designed for photovoltaic power generation systems. It mainly completes the collection, voltage boosting, protection and grid connection of the power generated by the photovoltaic inverter. It is widely used in centralized photovoltaic power stations, industrial and commercial distributed photovoltaic, household and agricultural photovoltaic/ fishery photovoltaic complementary projects.
I. Product Positioning and Application Scope
Voltage level: 0.69kV/0.8kV/1.14kV, boosted to 10kV or 35kV
Applicable scenarios: ground centralized photovoltaic power stations, mountainous photovoltaic power stations, fishery photovoltaic complementary, agricultural photovoltaic/fishery photovoltaic complementary, industrial and commercial rooftop distributed photovoltaic
Working mode: outdoor all-weather operation, unmanned, remote monitoring
Execution standards: GB/T 17467, GB/T 6451, NB/T 10397 photovoltaic-specific standards, etc.
II. Typical Technical Parameters
Low-voltage side: 0.69kV/0.8kV/1.14kV
High-voltage side: 10kV or 35kV
Capacity range:
10kV box transformer: 800kVA to 2500kVA
35kV box transformer: 1600kVA to 5000kVA
Short-circuit level: 20kA/25kA
Protection level: IP54 (box), internal IP4X
Environmental temperature: -40℃ to +55℃
Altitude: ≤4000m (customizable for high-altitude type)
III. Structural Composition (Modular Integration)
1. High-voltage room
Configuration: 10kV/35kV ring main unit, circuit breaker cabinet, load switch, PT, lightning arrester, metering device
Function: grid connection, line protection, high-voltage metering, lightning protection
2. Transformer room
Transformer: low-loss, low-noise, energy-saving oil-immersed transformer
Features: temperature control, oil level protection, pressure release valve, suitable for the intermittent power generation characteristics of photovoltaic
3. Low-voltage room (core of photovoltaic)
Photovoltaic incoming line circuit: multi-channel inverter output connection
Key configuration:
Low-voltage main switch, current collector copper bus
Anti-reverse current device/ grid connection controller
Lightning surge protector (SPD)
Power metering, reactive power compensation (optional)
Intelligent measurement and control, communication interface
4. Intelligent control cabin
Photovoltaic-specific integrated protection, measurement and control terminal
Support: remote signaling, remote measurement, remote control, remote adjustment
Communication: RS485, Ethernet, 4G/5G, IEC 61850, etc.
Access to photovoltaic power station monitoring platform, dispatching system
IV. Photovoltaic-specific Performance Characteristics
1. Adapt to intermittent and fluctuating photovoltaic power generation
The transformer and switch equipment can withstand frequent start-stop, voltage fluctuations, DC bias magnetic influence, and operate stably.
2. Multi-channel low-voltage collection, high integration
Can simultaneously connect multiple string-type / centralized inverters, reducing cable usage and reducing line loss.
3. High protection, outdoor unmanned
The box is anti-corrosion, sun protection, rainproof, and anti-condensation, suitable for complex environments such as fields, mountains, and water surfaces.
4. Complete grid connection protection
Equipped with overvoltage, undervoltage, overcurrent, overload, reverse power, frequency abnormality, islanding protection and other photovoltaic grid connection essential functions.
5. Quick construction, low cost
Factory pre-installation, overall transportation, only foundation installation and cable connection are required at the site, significantly shortening the construction period.
6. Intelligent, remote operation and maintenance
Support voltage and current monitoring, switch status, oil temperature, fault alarm, achieving unmanned.
V. Common Categories
1. 10kV photovoltaic box transformer
Used for small and medium-sized photovoltaic projects, low cost, flexible layout.
2. 35kV photovoltaic box transformer
Mainstream for large ground centralized photovoltaic power stations, long transmission distance, lower loss.
3. European-style box transformer / Chinese-style prefabricated cabin box transformer
European style: mature and reliable, high cost performance; prefabricated cabin: larger space, better heat dissipation, suitable for large-capacity power stations.

VI. Summary of Applicable Scenarios
Photovoltaic box transformers are the core equipment for voltage boosting and grid connection in photovoltaic power stations. They possess advantages such as high integration, fast construction, high reliability, and simple operation and maintenance. They are the standard configuration equipment for all types of photovoltaic power stations at present.