Transformer Solutions for Solar Farms & Wind Power Stations

Solar farms and wind power stations use transformers to collect generated electricity, increase voltage, and connect renewable energy systems to medium- and high-voltage networks.

Although both applications use similar transformer technologies, their electrical configurations and operating environments can differ. Transformer selection should therefore consider generation equipment, voltage levels, load characteristics, environmental conditions, and grid connection requirements.

Transformer Applications in Solar Farms

A typical solar power project may use transformers at different stages of the power conversion and grid connection process.

PV Step-Up Transformer

The inverter converts DC power from the PV array into AC power. A step-up transformer can then increase the AC voltage to the medium-voltage level of the collection system.

A typical configuration may be:

PV Array → Inverter → Step-Up Transformer → MV Collection System → Main Substation

Depending on the project design, the inverter and transformer may be installed as part of an integrated power station or as separate equipment.

Main Power Transformer

After electricity is collected at the medium-voltage level, a main power transformer can increase the voltage further for grid connection or transmission.

The required capacity and voltage ratio depend on the project generation capacity and grid connection requirements.

The required capacity and voltage ratio depend on the project generation capacity and grid connection requirements.

Transformer Applications in Wind Power Stations

Wind turbine transformers transfer generated power from the turbine generator to the medium-voltage collection network.

A typical configuration is:

Wind Turbine Generator → Wind Turbine Transformer → MV Collection System → Main Substation

Depending on the turbine design, the transformer may be installed in the nacelle, inside the tower, or near the tower base.

Wind turbine transformers should also be designed with consideration for vibration, available installation space, variable loading, and environmental conditions. Offshore projects may additionally require consideration of salt mist and corrosion. 

Key Transformer Selection Factors

Rated Capacity

Transformer capacity should be matched with the expected generation output and operating conditions.

The design should also consider load variation and the operating characteristics of the renewable energy system.

Voltage Ratio

The transformer voltage ratio should match the inverter or generator output, MV collection system, and grid requirements.

Temperature Rise and Cooling

Solar installations may operate under high ambient temperatures and strong solar radiation, particularly in desert and semi-arid regions.

Wind projects may also experience demanding outdoor conditions and, for offshore applications, salt mist and high humidity.

Transformer thermal design should therefore consider:

· Ambient temperature

· Temperature rise

· Cooling method

· Installation location

· Ventilation

· Environmental conditions

Inverter and Generator Characteristics

For solar projects, transformer design should consider the electrical characteristics of inverter-based systems, including harmonics, switching behavior, and variable loading where applicable.

For wind projects, transformer design should consider the turbine generator characteristics, collection voltage, variable loading, vibration, and installation constraints.

Dry-Type or Oil-Immersed Transformer?

Both dry-type and liquid-filled transformers can be used in renewable energy projects.

Dry-type transformers may be considered where fire safety, indoor installation, reduced oil-related risks, or space requirements are important.

Oil-immersed transformers may be considered for outdoor installations and applications requiring liquid-filled transformer technology.

The appropriate solution depends on capacity, installation environment, fire-safety requirements, maintenance arrangements, and project specifications. Both dry-type and liquid-filled technologies are used in solar and wind applications. 

Solar vs. Wind Transformer Selection

What Should Be Confirmed Before Ordering?

Before selecting a transformer for a solar or wind project, the following information should be confirmed:

· Rated capacity

· HV and LV voltage

· Frequency

· Connection group

· Impedance

· No-load loss

· Load loss

· Cooling method

· Insulation class

· Temperature rise

· Ambient temperature

· Installation altitude

· Enclosure or tank requirements

· Applicable standards

· Grid connection requirements

Providing these parameters during the quotation stage helps the manufacturer develop a transformer configuration that matches the project requirements.

Conclusion

Transformers are an important part of solar and wind power systems, from generation-side voltage conversion to MV collection and grid connection.

Solar projects may use PV step-up transformers and main power transformers, while wind projects may use wind turbine transformers and main power transformers.

The appropriate transformer solution depends on the generation equipment, voltage levels, capacity, load profile, environmental conditions, installation requirements, and grid connection specifications.

For renewable energy projects, evaluating electrical characteristics, losses, thermal performance, insulation, environmental conditions, and installation constraints together can help determine a suitable transformer configuration.