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

25 MVA - 300 MVA 115kV Solar Power Transformer For Sale

This 115kV oil-immersed solar transformer is specifically developed for modern utility-scale photovoltaic applications, providing a reliable step-down solution that bridges high-voltage collection with regional transmission networks. Rated from 25 MVA to 300 MVA, this three-phase transformer meets the diverse grid interconnection needs of large solar farms, ensuring stable and efficient energy delivery across North America and Europe.

Designed with a Delta-connected 115kV primary winding, the unit supports fully customizable secondary voltage outputs—commonly including 66 kV, 35 kV, 33 kV, and 11 kV—depending on regional distribution requirements. The core is constructed with grain-oriented low-loss silicon steel, paired with oxygen-free copper windings to reduce core losses and enhance thermal stability under continuous solar input.

Housed in a sealed, weather-resistant tank, the transformer is filled with high-grade insulating mineral oil, offering reliable thermal performance in harsh climates from Arizona deserts to northern Germany. ONAN/ONAF cooling systems ensure long-term temperature control, while optional OLTC (On-Load Tap Changer) and SCADA-integrated monitoring systems enable remote performance optimization.

In 2022, one of our 115kV 30MVA units was deployed in a coastal solar farm in southern Portugal. Despite high salt corrosion risks and extreme summer temperatures, the unit has run flawlessly, monitored remotely from a control center in Madrid. It now serves as the model design for our European solar deployments.

Built to IEC, IEEE, ANSI, and CSA standards, the transformer is rigorously tested for dielectric integrity, impulse resistance, and thermal cycling. Energy Transformer offers full OEM and ODM manufacturing, along with bulk delivery options across key solar markets including the United States, Canada, United Kingdom, Germany, France, Netherlands, Spain, Italy, Portugal, and Australia.

Whether for grid-tied solar stations, battery energy storage integration, or hybrid PV systems, this transformer delivers the performance, safety, and efficiency required for the evolving global energy landscape.

25 MVA - 300 MVA 115kV Solar Power Transformer Technical Specs

No.	Item	Specification	Remark
1	Rated Capacity	25 MVA to 300 MVA	Designed for large PV generation and export
2	High Voltage Side	115 kV (Delta or Wye input)	Optimized for regional transmission networks
3	Output Voltage	66 kV, 35 kV, 33 kV, 11 kV (customizable)	Supports diverse distribution systems
4	System Configuration	Three-phase, 50Hz / 60Hz	Global grid compatibility
5	Cooling Method	ONAN / ONAF (Oil cooling system)	Ensures stable operation in high ambient temps
6	Core Technology	Grain-oriented silicon steel	Minimizes eddy losses and magnetic resistance
7	Insulating Liquid	Premium-grade transformer oil	Safe thermal transfer and long insulation life
8	Heat Rise Limit	≤65°C (ONAN), ≤80°C (ONAF)	Maintains safe internal temps under load
9	Tank Structure	Anti-corrosive outdoor-rated steel	Suitable for field-mounted installations
10	Regulatory Standards	IEC, IEEE, ANSI, CSA-compliant	Ensures compliance for NA & EU grids
11	Certifications	CE, UL, CSA, SGS, RoHS	Third-party verified quality and safety
12	Wiring Schemes	D–Yn, Y–Y, D–D, Y–D (flexible)	Tailored per utility and EPC specifications
13	Suitable Projects	PV substations, grid interconnects, renewables	Built for high-capacity solar deployments
14	Protective Features	Thermal alarms, surge arresters, CT-integrated	Enhanced operational safety
15	Dimensions	Customized per voltage and capacity	Designs vary by model size and rating
16	Efficiency Profile	≥99.3% under rated load	High-efficiency output with reduced loss
17	Deployment Method	Skid, pad, or foundation mounted	Adaptable to various terrain or EPC needs
18	Working Temp Range	-25°C to +55°C	Built for variable environmental zones
19	Full Load Loss	1.3% max at rated conditions	Optimized loss reduction across operating cycles
20	Open-Circuit Loss	0.3% typical at idle	Lower parasitic consumption
21	Load Loss	≤1.0% at rated current	Supports steady performance under high draw
22	Impedance Range	5% to 7.5% typical	Balances fault isolation and voltage control
23	Fault Endurance	35 kA – 60 kA withstand	Passes high-fault short-circuit testing
24	Thermal Classification	Class A/B Insulation (105–130°C)	Handles extended high-load operation
25	Conductor Material	Copper or aluminum options	Copper for peak conductivity, Al for cost savings
26	Tap Control	OLTC or de-energized tap changer	Enables live voltage tuning under load
27	Bushing Material	Composite/polymer or porcelain	Weatherproof for outdoor deployment
28	Oil Capacity	1,000 – 4,500 liters (based on rating)	Scaled to ensure cooling performance
29	Life Expectancy	30–40 years with maintenance	Designed for long-term solar integration
30	Acoustic Profile	58 – 70 dB depending on size	Low noise for rural and industrial use
31	Warranty Support	2 to 5 years	Extended coverage available on request
32	Lead Time	8 – 12 weeks	Ready-to-ship or built-to-order options
33	Custom Orders	120 – 150 days based on scope	Full production traceability and QA process
34	Pricing	Request a formal quote	Based on spec, quantity, and delivery location

✅ 115kV Solar Power Transformer – Oil-Immersed Step-Down Unit for Utility-Scale PV Plants Overview

The 115kV oil-immersed solar power transformer is a high-voltage step-down unit designed specifically for large-scale photovoltaic (PV) power plants. It converts generated power from inverter-level voltages (typically 34.5kV or 33kV) down to grid-compatible high voltages, such as 115kV, for utility transmission. These three-phase, outdoor-rated transformers are equipped with high-quality windings, ONAN/ONAF cooling, and are engineered for high efficiency, low losses, and reliable long-term operation. ENERGY TRANSFORMER customizes each unit to comply with IEC, ANSI, IEEE, CSA, and EN standards for utility solar integration.

✅ 115kV Solar Transformer MVA Ratings (10 MVA to 300 MVA)

ENERGY TRANSFORMER manufactures 115kV solar step-up and step-down transformers with standard MVA ratings including 10 MVA, 20 MVA, 25 MVA, 40 MVA, 50 MVA, 63 MVA, and 80 MVA. These units serve as the electrical interface between PV inverters and regional transmission grids. All designs comply with IEC 60076 and IEEE C57 standards, and are tested for thermal, dielectric, and short-circuit performance. Suitable for both centralized utility PV farms and hybrid renewable installations.

✅ How to Calculate MVA for 115kV PV Grid Transformers

The MVA rating can be calculated using: MVA = (√3 × Voltage × Current) / 1,000,000. For example, a transformer operating at 115kV with 300A current has an approximate rating of 60 MVA. Proper sizing ensures compatibility with switchgear, fuses, overcurrent protection, and grid codes. ENERGY TRANSFORMER offers system studies, fault current analysis, and solar substation design consultation.

✅ What Is a 115kV Solar Step-Down Transformer?

A 115kV solar step-down transformer connects utility-scale PV plants to high-voltage transmission lines, stepping down voltage from 115kV to 34.5kV or 33kV. These units support continuous loads, integrate seamlessly with inverter feeders, and provide excellent thermal performance under variable solar generation. Features include OLTC or NLTC voltage adjustment, advanced winding insulation, and real-time monitoring. Ideal for solar farms, battery energy storage systems (BESS), and green hydrogen facilities.

✅ 115kV Transformer Dimensions for Solar Substations

Physical size depends on power rating. For example, a 40 MVA 115kV transformer may measure 6–7 meters in length, 3.5–4.5 meters in width, and 4–5 meters in height. ENERGY TRANSFORMER provides complete layout drawings, foundation dimensions, and top-view installation plans to facilitate site engineering and civil work preparation.

✅ Transport Weight and Handling of 115kV Solar Transformers

Weight varies with capacity. A 25 MVA unit may weigh around 45 tons (dry), while an 80 MVA unit may exceed 95 tons. Shipping weight with oil and accessories can reach over 120 tons. All units include lifting points, hoisting instructions, and center-of-gravity markings for safe logistics by truck, rail, or vessel. ENERGY TRANSFORMER assists with transport planning and route optimization.

✅ 115kV Transformer Pricing Factors

The cost of a 115kV solar power transformer depends on MVA rating, vector group, core material, copper or aluminum windings, accessories (OLTC, surge protection, sensors), and certification requirements. A 50 MVA model may range from $300,000 to $550,000 USD. ENERGY TRANSFORMER provides transparent quotations with EXW, FOB, and CIF options, and supports financing for qualified EPCs and developers.

✅ Full Load Current Reference for 115kV Solar Transformers

Use the formula: I = MVA / (√3 × kV). A 25 MVA unit at 115kV has a current of ~125A. ENERGY TRANSFORMER includes full load current data in technical drawings and nameplates to aid in breaker sizing, CT selection, and relay calibration. Optional SCADA-ready sensors available for real-time current monitoring and fault detection.

✅ Installation Guidelines for 115kV PV Transformers

Installation includes concrete foundation, oil containment, lightning protection, fire wall separation, and high-voltage fencing. ENERGY TRANSFORMER provides complete installation manuals, civil engineering references, and optional on-site commissioning support. Oil filtration, vacuum filling, and insulation resistance testing are available before energization.

✅ Tank Design, Conservator and Protection System

Each oil-immersed transformer features a sealed steel tank with anti-corrosion coating and welded seams. Conservator tanks include silica gel breathers, oil level indicators, and nitrogen-sealing options. Protection cabinets include Buchholz relay, pressure relief device, fan controller, temperature display, and SCADA-ready digital modules. Fault alarms and real-time diagnostics ensure high reliability.

✅ Voltage Classes and Vector Group Options

Standard secondary voltages: 33kV, 34.5kV, or 13.8kV. Common vector groups include YNd11, Dyn11, and YNyn0, selected based on grounding scheme and utility grid compatibility. ENERGY TRANSFORMER customizes vector group settings, tap ranges, and terminal arrangements to match PV substation requirements.

✅ Copper vs Aluminum Windings in 115kV Solar Transformers

Copper windings offer better conductivity and durability, while aluminum provides a cost-effective alternative. ENERGY TRANSFORMER offers both options using high-precision winding machines and multi-layer insulation for IEC/IEEE compliance. All windings undergo dielectric, impulse, and temperature rise tests.

✅ Transformer Efficiency and Losses

Typical full-load efficiency exceeds 99.4%. No-load loss for a 25 MVA transformer may be ≤30 kW, and load loss ≤160 kW. ENERGY TRANSFORMER uses low-loss core steel, optimized magnetic circuits, and enhanced oil flow cooling to minimize losses. IoT-based loss tracking systems available for digital O&M.

✅ Global Standards and Certifications

ENERGY TRANSFORMER units meet or exceed IEC 60076, IEEE C57, CSA, CE, and EN standards. Optional compliance with UL, ISO, UKCA, and NRTL certifications. FAT (Factory Acceptance Test) reports, third-party inspections, and routine/type/special test documentation included with every order.

✅ Nameplate and Documentation for 115kV Solar Transformers

Each transformer nameplate includes: rated MVA, primary/secondary voltages, frequency, vector group, weight, oil volume, cooling method, standard references, and serial number. ENERGY TRANSFORMER supplies digital datasheets, schematic drawings, vector group diagram, and bilingual nameplates (English/French or English/Spanish) upon request.

✅ Worldwide Delivery of 115kV Solar Transformers

ENERGY TRANSFORMER exports 115kV oil-immersed solar transformers to over 40 countries, including the USA, Canada, Germany, Spain, South Africa, Egypt, Saudi Arabia, UAE, and India. We support full-scope EPCs, solar developers, and utility tenders with fast lead times, documentation packages, and logistics coordination. Contact us for datasheets, technical support, and custom transformer design for your next PV project.

✅ Explore Related High Voltage Transformer Solutions

• 110kV Step-Down Transformers | 10–300 MVA Oil-Immersed Designs
• 132kV Utility Power Transformers | For Solar & Wind Farm Integration
• Heavy-Duty 66kV/69kV Transformers | 10–80 MVA Grid-Class Capacity
• 220kV/230kV High Voltage Transformers | 50–500 MVA Substation Use
• 33kV & 22kV Medium Voltage Transformers | For Urban Distribution

Featured Large-Capacity Oil-Immersed Power Transformers:
• 10 MVA 66kV/11kV Solar Step-Down Transformer – ONAN/ONAF Cooling
• 15 MVA 69kV/13.8kV Oil-Filled Substation Transformer – ANSI/IEC Certified
• 20 MVA 132kV to 33kV Grid Transformer for Renewable Energy Projects
• 25 MVA 110kV Oil-Immersed Transformer – Copper Windings, OLTC Ready
• 30 MVA 69kV/22kV High Voltage Transformer – Customizable Designs
• 40 MVA 115kV Solar Transformer for Utility-Scale PV Integration
• 50 MVA 220kV/66kV Step-Down Transformer – Designed for National Grids
• 63 MVA 132kV Outdoor Power Transformer – CE, UL & CSA Certified
• 75 MVA 110kV/33kV Transformer – Industrial & Utility Applications
• 100 MVA 230kV Oil-Immersed Power Transformer – Long Lifecycle Design

Why Choose 115kV Solar Power Transformer – Oil-Immersed Step-Down Unit for Utility-Scale PV Plants?

Energy Transformer's 115kV oil-immersed step-down transformer is purpose-built to deliver high-efficiency voltage regulation for solar PV farms, energy storage hubs, and utility-scale renewable integration. Designed with robust engineering and strict compliance in mind, this 3-phase transformer ensures long-lasting performance across grid applications.

✅ Tailored for Utility-Scale Renewable Integration
Engineered to convert generated solar energy from inverter stations to grid-compatible voltages, the 115kV transformer plays a crucial role in reliable solar power transmission across large-scale utility networks.

✅ Heavy-Duty Construction with Advanced Cooling
Featuring a sealed steel tank, high-conductivity copper windings, and ONAN/ONAF oil-based cooling, this unit ensures operational stability and thermal performance in harsh outdoor or substation environments.

✅ Meets International Compliance Standards
Manufactured in accordance with IEC 60076, IEEE, ANSI C57.12, and CE/UL/CSA certifications, the 115kV transformer meets the technical and safety requirements of energy projects across North America, Europe, and other global regions.

✅ Flexible Design for Project-Specific Demands
Voltage ratios, impedance, vector group configurations (Dyn11, YNd1, YNyn0), and OLTC options are fully customizable, supporting regional grid standards and ensuring smooth voltage control for dynamic solar operations.

✅ Efficient Production and Global Supply Chain
Backed by a vertically integrated supply chain, Energy Transformer ensures short lead times (60–90 days), on-time global deliveries, and expert technical support. Markets served include the USA, Canada, UK, Germany, France, Australia, and more.

📩 Get in touch with Energy Transformer today to discuss 115kV transformer specifications, capacity options (10–200 MVA), or solar EPC project requirements. Choose us for dependable quality, competitive pricing, and grid-proven reliability.