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Views: 0 Author: Site Editor Publish Time: 2026-03-13 Origin: Site
With the advancement of the "Dual Carbon" goals and the explosive growth of the new energy vehicle industry, Photovoltaic + Energy Storage + Charging Pile integrated projects (referred to as "PV-Storage-Charging") are becoming a hotspot in the energy sector. This model achieves on-site consumption of clean energy and flexible grid load regulation through the coordinated operation of "PV power generation, storage peak shaving, and charging pile power supply." Within this complex energy system, the transformer, serving as the core hub connecting PV, storage, charging piles, and the grid, directly impacts the efficiency, safety, and economic viability of the entire project through its selection and configuration. This article will systematically analyze the transformer technologies used in PV-Storage-Charging projects.
The electrical architecture of a PV-Storage-Charging integrated project typically includes the following elements:
PV Generation Unit: PV modules (DC 300~1500V) are converted to AC (typically AC 380V) via inverters.
Energy Storage Unit: Battery cabinets connect to the system via bidirectional Power Conversion Systems (PCS), enabling bidirectional power flow for charging and discharging.
Charging Pile Unit: Includes DC fast chargers (requiring AC 380V or DC fast charging interface) and AC slow chargers.
Distribution and Grid Connection Unit: Connects to the 10kV/20kV grid via a compact substation or switchgear room.
In a PV-Storage-Charging system, the transformer plays multiple critical roles:
First, Voltage Conversion and Matching. PV inverter output voltage fluctuates significantly with sunlight intensity (can drop below 200V on cloudy days). The energy storage system also outputs/absorbs power bidirectionally during charging/discharging, while charging piles require a stable AC 380V ±5% power supply. The transformer must support a wide input voltage range to ensure stable output voltage.
Second, Electrical Isolation and Safety Protection. PV-Storage-Charging systems involve bidirectional current flow on both the DC side (PV, storage) and AC side (charging piles, grid). The transformer achieves electrical isolation between input and output through magnetic coupling, blocking ground loop currents and surge interference, reducing total harmonic distortion to below 3%.
Third, Multi-Source Coordinated Energy Management Platform. Transformers in modern PV-Storage-Charging systems are no longer just "voltage converters"; they are core nodes for energy dispatch. By integrating an intelligent Power Management System (PMS), the transformer can monitor PV output, storage State of Charge (SOC), and charging pile load in real-time, automatically adjust taps, switch storage operating modes, and achieve intelligent dispatch such as "PV priority self-use → surplus power grid feed-in/storage → storage power supplementation → grid peak shaving."
In PV-Storage-Charging projects, based on different technical routes and application scenarios, the following main transformer solutions are available:
This is the most commonly used solution in current PV-Storage-Charging projects. A compact substation integrates high-voltage switchgear, transformer, and low-voltage distribution equipment into a movable enclosure, providing an integrated turnkey solution.
Technical Characteristics:
High Power Density: Volume is controlled to less than 1/3 of a traditional switchgear room, suitable for space-constrained scenarios like parking lots and industrial parks.
Wide Input Voltage Range: Supports AC 200~480V wide input range with built-in dynamic reactive power compensation modules.
High Ingress Protection: IP54 rating and above, adaptable to harsh outdoor environments like high temperatures, humidity, and salt fog.
Applicable Scenarios: Urban public charging stations, highway service areas, industrial park parking lots, etc.
Addressing the special "bidirectional power flow" requirements of energy storage systems, the industry has introduced dedicated transformers for energy storage and more highly integrated Integrated Storage Step-up Converter Units.
Energy Storage Dedicated Transformers:
Customized for energy storage application scenarios, featuring innovative structural designs and advanced processes.
Offers various options including oil-immersed, open-ventilated/epoxy resin dry-type.
Ensures high reliability and efficiency, suitable for various energy storage system integrations.
Integrated Storage Step-up Converter Units:
Integrates core equipment like transformers and converters in a containerized structure.
Requires no special lifting tools, convenient for transport and installation, providing an integrated turnkey solution.
High voltage side 6-35kV, low voltage side 0.315-0.69kV, single unit capacity up to 6.8MW.
Flexible choice between oil-immersed and dry-type to meet different scenario requirements.
Phase-shifting transformers are an emerging technical solution in the PV-Storage-DC-Flexible field in recent years. Companies like TY T have introduced dedicated transformers using high-frequency phase-shifting technology.
Technical Characteristics:
24-Pulse Rectifier System: Significantly reduces input current harmonics, eliminating the need for additional reactive power compensation.
Ultra-High Efficiency: System efficiency ≥98%, reducing total station losses from over 15% in traditional solutions to 5%.
Volume Advantage: 30%-50% smaller than traditional solutions.
Wide Power Operating Range: 5%~110% wide power operation, adaptable to the fluctuating nature of renewable energy power.
Applicable Scenarios: PV-Storage-Charging projects with high efficiency requirements and space constraints, especially charging stations in urban core areas.
The Solid-State Transformer (SST) represents a deep integration of power electronics and transformer technology, pointing towards the future direction of development.
Technological Breakthroughs:
AC/DC Hybrid Distribution: Enables efficient bidirectional power conversion between 10kV AC and 750V DC, constructing a flexible AC/DC hybrid distribution network framework.
Precise Control Capability: Allows precise control and coordinated operation of various elements like PV, storage, and charging facilities, making power dispatch as intelligent and flexible as "network routing."
Application Case: A PV-Storage-DC-Flexible Charging demonstration project jointly built by Guangzhou Weiguang Energy and Baiyun Electric Group, utilizing a 1250kVA solid-state transformer, successfully establishing a comprehensive demonstration station integrating PV, storage, ultra-fast charging, and V2G.
Applicable Scenarios: High-end demonstration projects, future smart industrial parks, scenarios demanding extremely high energy dispatch flexibility.
Harmonic Withstand Capability: Both PV inverters and energy storage PCS are power electronic devices that generate significant harmonics (5th, 7th harmonic distortion >8%). The transformer must possess adequate harmonic withstand capability to prevent additional heating and insulation aging.
High Efficiency and Low Loss: According to national standards, step-up transformers within PV arrays should preferably be energy-saving types with low no-load losses. Transformers for PV-Storage-Charging projects should select IE4 ultra-high efficiency transformers, maintaining efficiency ≥98.5% across 20%~100% load rates.
Bidirectional Power Adaptability: The bidirectional flow of charging and discharging in energy storage systems requires the transformer to adapt to changes in power flow direction, imposing higher demands on protection configuration and voltage regulation methods.
High Reliability Design: Harsh operating environments (high temperature, high humidity, salt fog, etc.) and complex load characteristics (intermittent, random) demand transformers with strong environmental adaptability and short-circuit withstand capability.
Integration: Evolution from standalone transformers to "multi-in-one" integrated equipment. Integrated Storage Step-up Converter Units combine transformers and converters; prefabricated cabin solutions integrate high-voltage ring main units, transformers, and power electronic modules.
Intelligence: Transformers with built-in sensors and communication modules support protocols like Modbus TCP and IEC 61850, uploading real-time data on voltage, current, temperature, and load rate, enabling remote condition assessment and predictive maintenance.
DC Orientation: "PV-Storage-DC-Flexible" is becoming an important technical direction. DC bus architectures (e.g., 750V DC bus) couple PV, storage, and charging piles directly on the DC side, significantly simplifying topology, achieving harmonic-free operation without reactive power compensation needs.
Transformer selection for PV-Storage-Charging projects requires comprehensive consideration of the following factors:
Consideration Dimension | Selection |
Project Scale | Small stations (<500kW): Compact substations suffice; Medium stations (500kW-2MW): Integrated Storage Step-up Converter Units are preferable; Large stations (>2MW): Consider phase-shifting transformers or solid-state transformers |
Space Constraints | Tight space: Prioritize phase-shifting transformers (30%-50% smaller) or solid-state transformers; Ample space: Traditional compact substation solutions offer better economics |
Efficiency Requirements | LCOE sensitive: Must select IE4 and above ultra-high efficiency transformers; Pursuing efficiency: Phase-shifting transformers (5% total station loss) are the best choice |
Intelligence Needs | Require remote monitoring and intelligent dispatch: Choose smart transformers supporting IEC 61850 communication with built-in sensors; V2G and microgrid needs: Solid-state transformer solutions offer more flexibility |
Budget Constraints | Limited budget: Combination of traditional compact substations + energy storage dedicated transformers; Pursuing technological leadership: Phase-shifting or solid-state transformers as differentiating features |
Key Parameter Checklist:
Rated Capacity: Determined by total power of PV, storage, and charging piles, considering diversity factor
Voltage Levels: High voltage side 6-35kV, low voltage side matching system voltage (380V/480V/690V, etc.)
Impedance Voltage: Affects short-circuit current levels and voltage regulation rate
Voltage Regulation Method: Off-circuit tap changing or on-load tap changing
Ingress Protection Rating: Outdoor IP54 minimum, higher for environments
Cooling Method: Natural air cooling or forced air cooling
PV-Storage-Charging integrated projects, as a typical scenario integrating new energy vehicle infrastructure with renewable energy, impose technical requirements on transformers far exceeding traditional distribution systems. From mainstream compact substations, to more highly integrated integrated storage step-up converter units, to highly efficient phase-shifting transformers, and future-oriented solid-state transformers—each technical solution has its applicable scenarios and unique value proposition.
The essence of transformer selection is finding the optimal balance between efficiency, cost, reliability, and intelligence that best meets project requirements. For most commercial projects, adopting compact substations or integrated storage step-up converter units, coupled with intelligent power management systems, already represents a mature and reliable solution. For benchmark projects pursuing efficiency and technological leadership, phase-shifting transformers and solid-state transformers demonstrate tremendous potential.
As the "PV-Storage-DC-Flexible" technical route matures and DC distribution becomes more prevalent, transformers are evolving from passive "voltage converters" into active "energy routers." Understanding this evolutionary trend will provide the most critical technical insight for your PV-Storage-Charging project investments.
