Solar PV Step-Up Power Transformer (6–220 kV, Oil-Immersed, ONAN/ONAF)

Comprehensive Product Overview for Utility-Scale Solar Farms

Manufactured by Energy Transformer – Professional PV Power Transformer Factory & OEM Supplier

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1. Introduction: Why Solar Farms Need Step-Up Transformers

As global energy systems transition toward renewable power, utility-scale solar photovoltaic (PV) farms are expanding at an unprecedented rate. However, even the most advanced PV modules and smart inverters cannot connect directly to the medium- or high-voltage power grid. To safely, efficiently, and reliably feed solar-generated electricity into the transmission network, the system requires a Solar PV Step-Up Power Transformer.

These transformers are positioned between the solar inverter output and the grid interconnection point, boosting the voltage from typical 0.27/0.315/0.4/0.6/0.69 kV to 6 kV – 35 kV – 110 kV – 220 kV, depending on the grid requirements. The grid cannot operate without this essential component, making PV step-up transformers a core asset of every solar power plant.

Energy Transformer, a leading transformer manufacturer in China, specializes in producing high-performance oil-immersed step-up transformers designed for utility-scale PV farms, grid-scale solar stations, and renewable energy substations. With decades of engineering experience, we provide custom, wholesale, and OEM PV transformers built to international standards including IEC, IEEE/ANSI, EN, and GB/T.

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2. Product Definitions and Positioning

A Solar PV Step-Up Power Transformer is a type of oil-immersed, ONAN/ONAF-cooled, distribution or power transformer designed specifically to handle:

• High current & harmonic-rich output from solar inverters

• Rapid load fluctuations caused by solar irradiance changes

• Outdoor desert, coastal, plateau, or tropical environments

• Integration into MV/HV collector systems

• High-efficiency voltage transformation for long-distance transmission

This transformer plays a pivotal role in increasing the voltage and ensuring stable grid connectivity. Energy Transformer provides units ranging from:

● Rated Capacity:

• 1 MVA – 2.5 MVA – 5 MVA – 10 MVA – 20 MVA – 50 MVA – 100 MVA+

● Voltage Levels:

• Low Voltage (LV): 0.27 kV / 0.315 kV / 0.4 kV / 0.6 kV / 0.69 kV

• Medium Voltage (MV): 6 kV / 10 kV / 11 kV / 22 kV / 24 kV / 33 kV / 35 kV

• High Voltage (HV): 66 kV / 110 kV / 132 kV / 150 kV / 220 kV

● Cooling Options:

• ONAN (Oil Natural Air Natural)

• ONAF (Oil Natural Air Forced)

● Insulation Class:

• Mineral oil Type I

• Optional: FR3 natural ester fluid

Read More：Solar Photovoltaic Transformer: A Critical Link in Solar Power Generation

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3. Key Technical Specifications (Overview Table)

Category	Specification	Options
Rated Power	1–200 MVA	Customizable
Primary Voltage	6/10/11/22/33/35/66/110/132/150/220 kV	Others on request
Secondary Voltage	0.27–0.69 kV	Compatible with all inverter brands
Winding Material	Copper (Standard), Aluminum (Optional)	High-conductivity Cu
Cooling Method	ONAN / ONAF	ODAF optional
Insulation Oil	Mineral Oil	FR3 Natural Ester
Vector Group	Dyn11, YNd1, YNd11, YNyn0	Special groups available
Frequency	50/60 Hz	Dual-frequency optional
Impedance	4%–12%	According to grid code
Standards	IEC/IEEE/GB/T	CE / ISO / ASTM compliant
Protection Level	IP44–IP55	Desert, coastal, salt-fog resistant

4. Why Energy Transformer PV Transformers Are Different

Solar power environments impose strict technical demands beyond typical industrial power systems. Our engineering team designs every PV step-up transformer to manage:

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4.1 Enhanced Thermal Performance for Solar Inverter Harmonics

Solar inverters produce THD 2–5% and generate additional thermal stress in transformer windings.
Therefore, Energy Transformer uses:

• Low-loss, high-permeability silicon steel

• Enlarged cooling ducts for optimized oil circulation

• Artificially oversized LV winding sections

• Harmonic-resistant insulation systems

This reduces:

• Temperature rise

• Hot-spot risks

• Dielectric degradation

• Overall energy loss

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4.2 Higher Efficiency for Long-Term Yield

Typical transformer efficiency ranges 98.3–99.5%, yet solar parks run for 25–30 years.
Therefore, efficiency impacts energy revenue directly.

Energy Transformer PV units achieve:

• Ultra-low no-load loss (Amorphous core optional)

• Reduced load loss with high-conductivity copper windings

• Energy savings of up to 5–8% annually

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4.3 Rugged Outdoor Protection

Solar farms are located in harsh environments:
☑ deserts
☑ freezing zones
☑ coastal salt-fog areas
☑ humid tropical regions
☑ high-altitude plateaus

We offer:

• Anti-corrosion paint (C4/C5 grade)

• Stainless steel fittings

• Hermetically sealed tanks

• IP55 protection optional

• Sandproof radiators

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4.4 Compatibility with All Major Solar Inverters

Our LV winding options match every top-brand inverter:

• Huawei

• Sungrow

• SMA

• Power Electronics

• TMEIC

• ABB / Fimer

• Schneider

Read More：How to Buy Power Transformers in Brazil

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5. Application Scenarios

Energy Transformer PV Step-Up Transformers are widely used in:

• Utility-scale solar farms (50–500 MW)

• Solar power substations

• Hybrid solar-battery storage plants

• Distributed solar microgrids

• Solar + wind hybrid energy parks

Each installation benefits from stable voltage transformation and long-term reliability.

Learn More：115kV Solar Power Transformer – Oil-Immersed Step-Down Unit for Utility-Scale PV Plants

6. Manufacturing Strength: Energy Transformer Factory

As a dedicated transformer manufacturer, OEM supplier, and export factory, Energy Transformer provides:

Full Production Capabilities

• Core cutting & stacking

• CNC winding fabrication

• Vacuum oil-filling

• Tank welding & shot blasting

• Full-type testing

Quality Control

• Partial discharge test

• Heat run test

• Induced AC withstand test

• Impulse voltage test

Certifications

• ISO9001

• ISO14001

• GB/T

• CE

• IEC Type Test Reports

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7. Customization & OEM Services

We support full customization based on:

• Capacity

• Voltage

• Vector group

• Cooling class

• Protection level

• Oil type

• Terminal/bushing type

• Smart monitoring systems

OEM/ODM branding with custom nameplates and packaging is available.

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8. Advantages of Choosing Energy Transformer

✔ Direct Factory Price

Manufactured in-house to reduce cost.

✔ High Engineering Expertise

30+ years of transformer design capability.

✔ Global Export Experience

Clients in 40+ countries: Southeast Asia, Middle East, Africa, Europe, LATAM.

✔ Strong After-Sales Support

On-site commissioning, remote guidance, lifetime technical service.

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9. Conclusion: The Optimal Transformer Solution for Modern Solar Farms

Solar PV power generation depends heavily on the performance and reliability of its step-up transformer. Energy Transformer provides high-efficiency, long-lifespan, grid-compliant, oil-immersed PV step-up transformers engineered specifically for utility-scale solar farms — including pad-mounted transformers for PV blocks, medium-voltage transformers for inverter stations, and HV substation transformers for grid interconnection.

From 6 kV to 220 kV, from 1 MVA to 200 MVA, from standard oil-immersed power transformers to fully customized ONAN/ONAF models, Energy Transformer is your global manufacturing partner for solar power transmission equipment. Our product line covers utility pad-mounted transformers, cast-coil dry-type transformers, distribution transformers, skid-mounted PV transformers, and EPC-grade booster transformers for solar farms across North America, Europe, and Asia-Pacific.