11kV to 0.8kV 1250 kVA Solar Power Transformer - Copper Wound High Efficiency PV Transformer
The 1250 kVA Solar Power Step-Up Transformer is a high-performance, inverter-duty solution specifically engineered for utility-scale photovoltaic (PV) installations. Designed to interface directly with 800V central or string inverters, this unit efficiently elevates voltage to 11kV for medium-voltage distribution. Unlike standard distribution transformers, our 1250 kVA model features 100% high-purity oxygen-free copper windings, offering superior thermal conductivity and lower losses. The core is constructed from laser-scribed, grain-oriented silicon steel to minimize eddy current losses, ensuring maximum energy harvest even during low-irradiance periods. With advanced harmonic mitigation technology, it withstands the high-frequency switching stresses typical of modern solar power conversion.
- Primary Voltage Ratings 11 kV/800V (Customizable up to 12kV)
- Secondary Voltage Ratings 0.315kV, 0.38kV, 0.48kV, 0.6kV, 0.69kV, 0.8kV or customized
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Solar Step-up Transformer
- BIL 30/200kV, 30/170kV, 30/150, 30/95 or others
- Standards IEEE, ANSI, NEMA, IEC, GB
- Application Utility-Scale Solar Farms & Centralized Power Plants
- Power Rating 1250 kVA
- Certificate UL ,CESI
- Cooling Method ONAN, KNAN
- Opeartion Step-up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
11kV to 0.8kV 1250 kVA Solar Power Transformer - Copper Wound High Efficiency PV Transformer
Technical Specifications
Accessories
| Rated Power | 1250kVA | |
| Rating Primary Voltage | 11kV/800V | |
| Secondary Voltage | Customized | |
| Frequency | 50/60Hz | |
| Vector Group | Dyn11,Ynd11,Dyn11yn11,YNd11d11 | |
| Winding Material | Aluminum/Copper | |
| Zero-Sequence Impedance | Customized | |
| Altitude | ≤1,000m or Customized | |
| Color | ANSI 70 Light gray/Munsell 7GY3.29/1.5 or customized etc | |
| Tank material | Mild Steel, 304 Stainless Steel | |
| HV Bushing |
| LV Bushing |
| Tap changer |
| Oil level gauge |
| Oil temperature indicator |
| Pressure relief device |
| CT |
| Lifting hook for complete transformer |
| Name plate |
| Radiators |
| Oil upper filtering valve |
| Oil drain valve with 3/8" sampler |
| Terminal box |
Customization Optional
11kV to 0.8kV 1250 kVA Solar Power Transformer - Copper Wound High Efficiency PV Transformer
We offer tailored electrical configurations to meet the specific requirements of international solar projects. Our 1250 kVA units can be designed with dual-low voltage windings to accommodate two separate 625kVA inverter inputs, reducing overall site footprint and balance-of-system (BOS) costs. Customers can choose between mineral oil (IEC 60296) or biodegradable synthetic ester fluids (FR3) for projects located in environmentally sensitive areas or fire-risk zones. Additionally, we provide custom vector groups and impedance ratings to match your specific grid-connection studies and protection coordination requirements. On the mechanical and monitoring side, we provide "Smart Transformer" integration packages.
This includes the installation of fiber-optic temperature sensors directly within the copper windings for precise "hot-spot" monitoring, as well as integrated nitrogen-blanketed sealing systems to extend oil life. Enclosures can be customized with C5-M high-corrosion resistant coatings for coastal salt-spray environments or specialized solar-shielding paint to reduce solar gain in desert climates. We also offer flexible connection interfaces, including plug-in bushings or side-mounted cable boxes, allowing for seamless integration into pre-fabricated containerized substations.
Packing and Shipping
11kV to 0.8kV 1250 kVA Solar Power Transformer - Copper Wound High Efficiency PV Transformer
Our global shipping strategy for the 1250 kVA transformer is centered on vibration-dampened protection. Before departure, each unit is secured to a heavy-duty reinforced steel skid that acts as a vibration isolator. The transformer is wrapped in a multi-layered VCI (Vapor Corrosion Inhibitor) heat-shrunk film that creates a chemical barrier against oxidation, essential for long-term sea freight. All external components, such as the conservator tank and high-voltage bushings, are protected by custom-built timber enclosures to prevent impact damage during crane operations.
For sea freight logistics, we utilize 20ft Flat Rack or Open Top containers depending on the final assembly height. We implement a rigorous "Double-Tie" down method using industrial-grade steel lashing and turnbuckles, ensuring the unit remains immobile even in sea states exceeding Force 6. For liquid-filled units, we maintain a specific oil level to allow for thermal expansion during transit through different climate zones, with the tank pressurized with dry nitrogen to prevent moisture ingress.Inland transport involves the use of specialized hydraulic trailers equipped with air-ride suspension.
This minimizes the risk of internal core-shifting or loosening of the copper winding braces. We provide comprehensive tracking for every 1250 kVA unit, utilizing GPS-enabled shock sensors that record real-time G-force data. If a preset threshold is exceeded, an automated alert is sent to our quality team, triggering a mandatory internal inspection upon site arrival to guarantee the unit’s structural integrity before commissioning.The final stage of our delivery process includes comprehensive documentation and unloading support.
We provide a detailed "Site Receiving Guide" and digital CAD drawings of lifting points to the project contractors. Our packing list is digitized and integrated with QR codes on each crate, allowing site managers to quickly verify components against the project inventory. We offer DDP (Delivered Duty Paid) services to most global solar hubs, managing all customs clearance and local haulage to ensure your project stays on its critical path schedule.
For sea freight logistics, we utilize 20ft Flat Rack or Open Top containers depending on the final assembly height. We implement a rigorous "Double-Tie" down method using industrial-grade steel lashing and turnbuckles, ensuring the unit remains immobile even in sea states exceeding Force 6. For liquid-filled units, we maintain a specific oil level to allow for thermal expansion during transit through different climate zones, with the tank pressurized with dry nitrogen to prevent moisture ingress.Inland transport involves the use of specialized hydraulic trailers equipped with air-ride suspension.
This minimizes the risk of internal core-shifting or loosening of the copper winding braces. We provide comprehensive tracking for every 1250 kVA unit, utilizing GPS-enabled shock sensors that record real-time G-force data. If a preset threshold is exceeded, an automated alert is sent to our quality team, triggering a mandatory internal inspection upon site arrival to guarantee the unit’s structural integrity before commissioning.The final stage of our delivery process includes comprehensive documentation and unloading support.
We provide a detailed "Site Receiving Guide" and digital CAD drawings of lifting points to the project contractors. Our packing list is digitized and integrated with QR codes on each crate, allowing site managers to quickly verify components against the project inventory. We offer DDP (Delivered Duty Paid) services to most global solar hubs, managing all customs clearance and local haulage to ensure your project stays on its critical path schedule.
32
32 years of industry experience
Manufacturer Test
11kV to 0.8kV 1250 kVA Solar Power Transformer - Copper Wound High Efficiency PV Transformer
Progress Test
Progress testing for the solar power transformer is conducted through structured inspections at critical production stages. Incoming materials, including copper conductors, core steel, insulation materials, and insulating oil, are verified for compliance with design specifications. During winding assembly, inspections focus on conductor placement accuracy, insulation layering, and dimensional consistency. Core assembly is monitored to ensure magnetic alignment and mechanical stability.
After winding completion, the active part undergoes controlled drying and vacuum treatment to achieve specified moisture limits. Intermediate electrical inspections, such as winding resistance measurement and turns ratio verification, are carried out before tank installation. Tank fabrication is inspected for welding quality, dimensional accuracy, and coating integrity. Prior to oil filling, leak testing and internal cleanliness inspections are performed. All results are documented to ensure quality traceability and readiness for final acceptance testing.
Design Tests
Design tests are critical type tests used to verify the rationality of transformer design and long-term operational reliability. They are typically performed on prototypes or representative products within the same series. Tests include temperature rise tests to verify that winding and oil temperatures meet design limits under rated load; lightning impulse withstand tests to assess the insulation strength of the transformer under transient overvoltage conditions in the power grid; and short-circuit withstand tests to confirm the stability of the windings and mechanical structure under short-circuit electrodynamic forces. Additionally, noise measurement tests may be included to verify that the product meets environmental and power plant noise standards. The results of all design tests provide a basis for verifying the product design, ensuring it meets relevant IEC or IEEE standards.
Transformer Factory Acceptance Test
Factory Acceptance Testing ensures the operational readiness of the PV transformer before delivery. Electrical routine tests verify resistance balance, voltage ratio accuracy, phase displacement, and insulation resistance levels. High-voltage testing confirms the transformer’s ability to withstand rated operating conditions.
Thermal performance is validated through temperature rise testing, while efficiency is confirmed by loss and impedance measurements. Partial discharge testing evaluates internal insulation quality. Mechanical and functional checks include oil leakage testing, cooling equipment operation, monitoring device verification, and safety component inspection. Oil samples are analyzed for dielectric strength and moisture content. FAT documentation is completed for customer approval.
Routine Test - On load Loss Test
Purpose of Testing
The purpose of On-load Loss Test is to measure the active power loss of the transformer under rated voltage and rated load, evaluate its energy efficiency level and design compliance, and provide a basis for energy consumption calculation and performance optimization during operation.
Testing Equipment
Power transformer test system (e.g. OMICRON, ISA, Tettex, Vanguard, etc.)
Voltage source and current source (usually rated voltage, or adjusted according to the test standard, such as 10 KV, 20 KV, 35 KV, etc.)
Temperature and humidity meter (used to record ambient temperature and humidity for correction of test data)
Voltage source and current source (usually rated voltage, or adjusted according to the test standard, such as 10 KV, 20 KV, 35 KV, etc.)
Temperature and humidity meter (used to record ambient temperature and humidity for correction of test data)
Pre-Test Preparation
Disconnect the transformer high voltage, low voltage and neutral power supply to ensure that the equipment is properly grounded and safely discharged.
The test environment should be dry and rainless, with a relative humidity of less than 75% and a recommended temperature range of 20–30°C.
The test environment should be dry and rainless, with a relative humidity of less than 75% and a recommended temperature range of 20–30°C.
Test Progress
Connect the Test Instrument:
Connect the test equipment to the appropriate terminals of the device under test and ensure that all wiring is correct and the device is well grounded.
Apply Test Voltage:
Apply the specified test voltage at the rated frequency and adjust the low voltage side to maintain the rated current (or specified current).
Connect the test equipment to the appropriate terminals of the device under test and ensure that all wiring is correct and the device is well grounded.
Apply Test Voltage:
Apply the specified test voltage at the rated frequency and adjust the low voltage side to maintain the rated current (or specified current).
Measure and Record
Start the test and record the following parameters:
On-Load Loss Power
Input Power and Output Power
Current
Voltage
Temperature (temperature rise or winding temperature)
Ambient temperature and humidity during the test
On-Load Loss Power
Input Power and Output Power
Current
Voltage
Temperature (temperature rise or winding temperature)
Ambient temperature and humidity during the test
Temperature Correction
The measured loss data is corrected based on a reference temperature (usually 20°C) to ensure the accuracy of the results.
Repeat Testing (if necessary)
Test different tap positions (Tap Changer) and record and compare the load loss data of each tap point.
Evaluation Criteria (Reference)
Evaluate the test results based on the equipment type and manufacturer requirements. If the load losses are low and the efficiency is high, it is considered "normal".
Test standard
IEEE C57.12.01 & IEEE C57.12.91 (Dry-Type)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Ideal for large-scale factory-integrated PV systems where a dedicated 1250 kVA transformer is required to isolate solar generation from the building’s internal 400V load while feeding the grid at 11kV.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
Product Packaging
Transformers Packaging (1)
Transformers Packaging (2)
Transformers Packaging (3)
Transformers Packaging (4)
Transformers Packaging (5)
Transformers Packaging (6)
Transformers Packaging (7)
Transformers Packaging (8)
Related Products
2500kVA Dry Type Transformer
The NPC ELECTRIC 2500kVA Dry Type Transformer is a high-capacity, reliable power solution designed for large industrial and commercial applications. With a power rating of 2500kVA, it features advanced dry-type insulation technology, offering superior safety, low maintenance, and long-term performance. Engineered to operate efficiently in demanding environments, this transformer delivers stable, noise-free power while minimizing environmental impact.
11kV – 33kV Solar Inverter Duty Transformer Up to 20MVA
The Reliable Solar Inverter Duty Transformer for Renewable Energy applications is engineered to support modern photovoltaic systems with capacities up to 20MVA and voltage levels from 11kV to 33kV. Designed to interface directly with solar inverters, this transformer ensures stable voltage conversion, excellent harmonic tolerance, and consistent performance under fluctuating generation conditions typical of renewable energy plants. The transformer adopts a robust oil-immersed structure with optimized thermal management to handle continuous load cycling and high ambient temperatures. Advanced magnetic core materials reduce no-load losses, while reinforced insulation systems improve dielectric strength and operational lifespan.
130kV 10MVA / 25MVA / 40MVA Electrical Power Transformer
The 130kV Electrical Power Transformer with ratings of 10MVA, 25MVA, and 40MVA is designed to support medium-to-large capacity power transmission and distribution systems. It is engineered to provide consistent voltage conversion, high operational efficiency, and excellent thermal stability under variable grid conditions. The transformer incorporates a precisely calculated magnetic core, high-strength winding design, and an oil-immersed insulation system that enhances heat dissipation and electrical reliability. Its structure is optimized to withstand electrical stress, mechanical vibration, and long-term continuous operation. Suitable for outdoor installation, the transformer maintains stable performance in challenging environments such as high temperature, humidity, or heavy industrial zones. Built in accordance with recognized international standards, it offers dependable service life and reduced maintenance requirements for modern power networks.
25kVA Completely self-protected(CSP) Single Phase Pole Mounted Transformer
25 kVA Completely self-protected(CSP) Single Phase pole Mounted transformer is an efficient and reliable power equipment designed for small and medium-sized power needs. It is widely used in power distribution systems in residential areas, commercial areas, and small industrial facilities. The transformer adopts fully self-protection technology and has built-in multiple protection functions such as overload, short circuit, overvoltage, etc. to ensure automatic power failure under abnormal conditions, avoid equipment damage, and improve system safety. High-quality manufacturing materials and reliable performance ensure its long-term stable operation, reduce energy waste, and improve power supply efficiency.
75kVA Conventional Type Single Phase Pole Mounted Transformer
NPC ELECTRIC has been specialized in manufacturing 75kVA Conventional Type Single Phase pole Mounted transformer for more than 20 years, which complies with international standards such as ANSI/IEEE C57, IEC60076 and other standards. Its main function is to convert high voltage electricity (such as 11kV, 13.8kV, etc.) into low voltage electricity (such as 120V/240V), providing stable and reliable power supply to end users. It is suitable for residential, commercial, agricultural and small industrial loads.
55kV 1600kVA Three Phase Oil Immersed Power Transformer Copper
The 55kV 1600kVA Three Phase Oil Immersed Power Transformer Copper is designed for reliable medium/high-voltage distribution networks. It adopts 99.95 % electrolytic copper windings, Class A insulation, a corrugated-fin tank, and ONAN cooling for excellent heat dissipation. Available in energy-saving S11/S13 series with no-load loss reduced by up to 35 %. Fully sealed or conservator type prevents oil aging. Equipped with ±5 % or ±2×2.5 % off-circuit tap changer (on-load optional). Meets IEC 60076, GB/T 1094 standards, lightning impulse withstand 250 kV peak, PD <10 pC. Low noise (<58 dB), strong short-circuit strength, suitable for harsh environments. Vacuum oil filling + nitrogen sealing ensures a 30+ year lifespan. Widely trusted in mining, petrochemical, renewable energy, and urban 55 kV substations.FAQ From Customers
-
What is a Transformer?A transformer is an electrical device used to change the voltage of alternating current (AC). It works on the principle of electromagnetic induction, converting high-voltage current into low-voltage current or low-voltage current into high-voltage current. Transformers are widely used in power transmission, distribution systems, and various electronic devices.
-
What are the main uses of a transformer?The main use of a transformer is voltage conversion. Transformers are used in power transmission systems to help transfer electricity from power plants to consumers. In addition, transformers are also used in electronic devices such as chargers, televisions, power adapters, etc., to adjust the voltage to meet the requirements of different devices.
-
Do you have UL listed?Yes, our transformer has UL listed. We have exported to America many pad mounted transformer,substation transformer and HV.
Welcome your inquiry
Honesty, Integrity, Frugality, Activeness and Passion