Blolew 35 kV,400–10000 kVA Photovoltaic Combined Transformer

The DINGXIN Photovoltaic Combined Transformer is a purpose-built pad-mount transformer designed for solar PV inverter step-up and PV plant collector network applications. Covering a capacity range from 400 kVA to 10000 kVA, each unit integrates the transformer body, high-voltage switchgear, fuse, tap switch and auxiliary equipment into a single, factory-tested outdoor enclosure — serving as the central step-up node between the PV inverter array and the medium-voltage grid.

The transformer steps up the inverter output — typically 0.27 kV / 0.315 kV / 0.4 kV / 0.69 kV — to the collector-grid level of 10 kV / 35 kV / 38.5 kV, enabling direct interconnection with the PV plant's medium-voltage network. The stepped-up power is then transmitted to the plant substation via buried cable or overhead line.

As photovoltaic power generation becomes an increasingly important component of global energy production — driven by the worldwide push for clean, sustainable energy — DINGXIN PV combined transformers are engineered to meet the specific demands of modern solar plants:

• Inverter-output step-up — handles the harmonic-rich, potentially DC-biased current profile of PV inverters with appropriate winding design and insulation margin.

• Collector-line interconnection — supports both terminal (Z) and ring-main (H) wiring for flexible PV plant topology, including ring-main configurations specific to PV network requirements.

• Outdoor long-term exposure — IP68 oil tank and IP45 chambers withstand prolonged UV, dust, humidity and thermal cycling.

• Compact & economical — small footprint, low investment, easy installation and maintenance, and aesthetic integration with the surrounding environment.

Two structural configurations are offered:

Split-Cabin Architecture

For large PV installations, DINGXIN offers a split-cabin structure in which the high-voltage cabin, low-voltage cabin and transformer cabin form three independent units. The HV outgoing unit and LV incoming unit are physically separated from the transformer, providing enhanced safety and reliability. The cabin layout can be configured as mesh-type, linear (I-shaped), or L-shaped to suit the site footprint and collector-cable routing of any PV plant.

• Optimized for PV Inverter Step-Up Duty Engineered specifically for the voltage, harmonic and thermal profile of solar inverter outputs. Winding design and insulation class account for the DC injection potential and harmonic-rich current that PV inverters produce — stresses that standard distribution transformers are not designed to handle.

• Factory-Integrated, Fast Deployment Transformer, HV switchgear, fuse, tap switch and auxiliary equipment are all integrated and factory-tested in one enclosure. On-site work is limited to foundation placement, cable connection and commissioning — reducing PV plant construction time and labor cost.

• Flexible Terminal & Ring-Main Collector Wiring Both terminal (Z) and ring-main (H) wiring schemes are supported, enabling flexible collector-line design for radial, looped or hybrid PV plant topologies. This allows optimization of cable runs and redundancy based on plant size and grid interconnection requirements.

• IP68 Sealed for Long-Term Solar Exposure The oil tank is rated IP68 and each unit passes a 50 kPa / 12-hour sealing test. The sealed enclosure resists UV degradation, dust ingress, humidity penetration and daily thermal cycling — environmental stresses that are particularly intense in desert, tropical and high-altitude PV plant locations.

• Dual-Box Independent Maintenance The fully insulated sub-box type separates the transformer and HV components into two independent enclosures, allowing the HV section and transformer to be maintained separately. This minimizes plant downtime and is especially valuable for utility-scale PV plants where transformer availability directly affects revenue.

• Split-Cabin Design with Direct-Air Radiator Fins The split-cabin structure places the HV cabin, LV cabin and transformer cabin as independent units — with the HV outgoing and LV incoming units physically separated from the transformer for maximum safety. The radiator fins are directly exposed to ambient air, delivering strong heat dissipation and preventing equipment failures caused by excessive internal cabin temperature.

• High Overload, Low Loss, Superior Protection Engineered with strong overload capacity, low losses, and excellent short-circuit and lightning protection. The enclosure is treated with anti-corrosion spray coating that withstands seawater and salt-spray exposure, and incorporates anti-theft features — making the unit suitable for unattended sites in coastal, desert and remote locations. High automation with agile communication supports remote monitoring integration.

PV Transformer Main Parameters

Service Conditions

Standards & Compliance

Energy Efficiency Levels (35 kV Class Oil-Immersed, PV / Wind / Storage Duty)

NX1 is the highest energy-efficiency level (lowest loss), helping PV plant owners reduce auxiliary power consumption and carbon emissions over the 25+ year plant lifecycle.

Model Code Description

Combined Transformer — G (Sharing Box) / F (Divided Box) — Three Phase — Performance Level Code — Terminal Type — Photovoltaic Power Generation — Rated Capacity (kVA) — Transformer Voltage Class (kV)

• Utility-Scale PV Plants — Centralized inverter step-up and MV collector-line interface for 10 MW to 500 MW+ solar farms; ring-main wiring enables redundant collector topology.

• Distributed PV / Commercial Rooftop — Compact capacity units for inverter step-up at commercial and industrial rooftop installations; terminal wiring for simple radial interconnection.

• String Inverter PV Plants — Multiple small-capacity combined transformers distributed across the array, each serving a string inverter cluster.

• Floating Solar (FPV) Plants — IP68 sealed enclosure engineered for high-humidity, water-adjacent environments; sealed tank prevents moisture ingress.

• Desert PV Plants — Dust-resistant sealed enclosure with plug-type arrester; withstands daily thermal cycling from −10 °C night to +55 °C day.

• High-Altitude PV Plants — Rated for altitudes up to 3000 m; fully insulated design eliminates flashover risk in thin-air, high-irradiance environments.

• Agrivoltaic (Solar + Agriculture) — Compact footprint minimizes land use; outdoor-rated enclosure co-exists with agricultural operations.

• PV-Plus-Storage Hybrid Plants — Combined transformer for PV inverter step-up with battery energy storage system (BESS) integration at the MV collector bus.

DINGXIN photovoltaic combined transformers are engineered to project-specific requirements. The following customization options are available:

Contact DINGXIN with your PV project specification (inverter type, plant capacity, grid voltage, site conditions) for a tailored quotation.

Q1: What is a photovoltaic (PV) combined transformer? A PV combined transformer is a compact pad-mount unit designed for solar PV power plants. It steps up inverter output to the medium-voltage grid level and integrates the transformer body, HV switchgear, fuse and auxiliary equipment into a single outdoor enclosure, simplifying collector-line design for utility-scale and distributed PV projects.

Q2: How does a PV combined transformer differ from a standard distribution transformer? A PV combined transformer is purpose-built for solar plant topology: it handles the specific voltage and harmonic profile of inverter outputs, integrates HV switchgear and fuse protection in one enclosure for direct outdoor installation, and supports both terminal and ring-main collector-line wiring. Standard distribution transformers do not offer this level of integration or solar-specific engineering.

Q3: What structural types are available? (1) Fully insulated sub-box type — transformer and HV components in two independent boxes for separate maintenance. (2) Porcelain sleeve outlet box type for traditional installations. The fully insulated type is recommended for new utility-scale PV plants.

Q4: What protection level does the enclosure provide? The oil tank is rated IP68 and the HV/LV chambers are rated IP45. Each tank passes a 50 kPa / 12-hour sealing test to guarantee zero oil leakage under long-term outdoor UV, dust and humidity exposure.

Q5: Can the PV transformer handle inverter harmonics and DC injection? Yes. DINGXIN PV combined transformers are engineered to handle the harmonic-rich, potentially DC-biased current profile of PV inverter outputs. Winding design and insulation margin account for the specific thermal and dielectric stresses of solar inverter step-up duty.

Q6: What environmental conditions can the unit withstand? Altitude ≤ 3000 m, ambient temperature −40 °C to +45 °C, outdoor wind speed ≤ 30 m/s, daily-average humidity ≤ 95%, monthly-average ≤ 90%. The sealed enclosure withstands prolonged UV exposure, dust and thermal cycling typical of desert and tropical PV plant locations.

Q7: Which standards does the product comply with? IEEE C57.12.00, IEEE C57.12.10, IEEE C57.12.34, IEC 60076-1, IEC 60076-2, IEC 50588 and IEC 62271-202. Full type-test reports and FAT documentation are provided.

Q8: Can the PV transformer be customized for different inverter ratings and plant sizes? Yes. Rated capacity, primary/secondary voltages, terminal or ring-main wiring, connection group, tap range, oil type (mineral or ester), and monitoring options can all be customized to match inverter ratings from small commercial to utility-scale PV plants.