1,000+ Electrical Transformers (7.2–34.5 kV, 25–3000 kVA) — UL Evaluated, Certificate of Compliance Available — In Stock & Ready to Ship from Houston, CA & Florida. Contact Us Today!
Universal Compatibility with All Leading Inverter Models
Superior Protection Against High Harmonics & Transients
Optimized for Bidirectional BESS & Grid Integration
Standard transformers cannot meet the demands of solar power plants – they overheat and age quickly, insulation loses its properties earlier and failures occur, usually after 5-8 years. Solar inverter duty transformers from Daelim Belefic are engineered to handle the unique demands of solar power generation, delivering reliable performance under the dynamic and challenging conditions associated with photovoltaic systems.
Every parameter of these transformers is adapted to work with inverter-coupled PV and BESS, meaning no retrofit of existing distribution transformers is performed. Daelim Belefic uses its many years of experience to deliver high-performance transformers for renewable projects around the world.
Daelim Belefic’s solar inverter duty transformer is mainly available in oil-immersed and dry type configurations, manufactured according to IEC 60076, ANSI/IEEE C57.12.00, CSA C88, and AS/NZS. All parameters are according to the inverter output, and this is defined before ordering.Daelim Belefic does not rely on generic transformer sizing—each unit is precisely engineered to match the specific requirements of your project.
Parameter | Specification |
Rated capacity | 100 kVA – 20 MVA (single unit), higher ratings via multi-winding or parallel configurations |
HV side | Up to 35000 V (or as required by grid interconnection point) |
LV side | Up to 1000 V |
Frequency | 50 / 60 Hz |
Phases | Three-phase is standard. Single-phase is also available upon request. |
Winding configuration | Standard: Two winding |
Cooling method | ONAN/ONAF (oil-immersed unit) |
Core material | CRGO silicon steel |
Winding material | Electrolytic copper – standard Aluminium – on request |
Insulation class | Class A (oil) Class F/H (dry type= |
Tap changer | Off circuit ±2×2.5% |
Maximum inverter overload | Sized to maximum inverter output power per IEEE best practice |
Ambient temperature | −25°C to +50°C standard Desert and arctic versions available |
Altitude | ≤ 1,000 m – standard 4,000 m+ available upon request with enhanced cooling |
Noise level | ≤ 65 dB at 1 m – standard ≤ 50 dB low-noise versions |
Applicable standards | IEC 60076-1/2/3, ANSI/IEEE C57.12.00, IEEE 1547, IEEE 519, CSA C88, AS/NZS 60076, UL/cUL |
To ensure the most accurate and optimized transformer solution, detailed inverter data—such as maximum output power, output voltage, THD spectrum, and electrical schematics should be provided to Daelim Belefic’s engineering team prior to quotation. This enables precise analysis and a design fully aligned with your project requirements.
Each of our solar inverter duty transformers is characterized by engineering solutions that adapt to work in the renewables sector. These are the main differences compared to standard transformers. All of the above features are part of the standard design – and not a matter of choice when ordering a transformer.
Feature | Challenges & Customer benefit |
Reduced core flux density (-5% to -10% compared with standard transformers) | ● Solar inverters generate irregular voltage waveforms that increase the flux through the transformer, pushing the core towards saturation. ● Daelim Belefic solar inverter duty transformers are designed with -5% to -10% lower flux density than standard transformers. ● This leaves room for the inverter to influence the transformer operation within the allowable range, which eliminates increased current, noise and additional transformer heating. |
Electrostatic shield | ● Electronic switching in modern inverters can cause transient voltages with a peak of 7x higher than the nominal. ● To prevent insulation breakdown between the HV and LV windings, Daelim Belefic transformers use an electrostatic shield. ● This protection blocks capacitive transients in both directions, preventing relay misoperation and system communication problems. |
Double-split winding architecture | ● Large PV plants pair inverters to a single transformer. In these cases, circulating currents appear, losses are higher and harmonics are more significant. ● The double-split architecture allows for two separate LV transformer windings, which eliminates circulating currents. ● This is also a good design for short circuits, as a problem in one winding will not spill over to the other winding. |
Reverse power flow design | ● Most standard transformers allow energy flow only from the HV to the LV side. ● Daelim Belefic solar inverter duty transformers allow energy flow on both sides. In any case, appropriate relay settings, transformer cooling and all other available operating modes are ensured. |
Oversizing to maximum inverter output | ● Many modern inverters can deliver more than their rated power under controlled conditions. ● If the transformer is designed for the inverter’s nameplate, such operation can lead to overheating and insulation aging, and ultimately failure. ● Each of our transformers is rated for the maximum output of the inverter, not the nominal rating. |
FR3 natural ester insulating fluid | ● Many solar power plants are located in sensitive environmental areas. Daelim Belefic offers a special FR3 natural ester insulating fluid as an alternative to mineral oil. ● This oil has a high flash point and significantly reduces the possibility of fire on site. Natural ester fluid is also biodegradable and non-toxic. It also absorbs moisture from the windings and insulation system, extending its service life. |
These are the most common application scenarios for solar inverter duty transformers. A 100 MW solar power plant may have 50-100 transformers, each paired with one or two inverters on a MV/HV collector bus. Daelim Belefic has completed a large number of solar power plant projects in the United States, Canada, Australia and throughout Asia. Our engineering team performs inverter-transformer relationship calculations, vector group coordination and relay protection settings to ensure optimal transformer operation.
When electricity storage is close to solar power generation, transformers must handle bidirectional power flow. Due to this mode of operation, transformers are loaded 18-24 hours a day, instead of only being loaded during solar power generation. Our transformers use advanced ONAF cooling, reinforced winding insulation and a special configuration that allows for trouble-free operation.
Solar installations on commercial buildings, industrial plants, logistics and data centers require compact, quiet and optimal transformer solutions. These transformers need to comply with often very rigorous building codes, occupational health and safety and fire protection regulations.
Pad-mounted solar IDT solutions from Daelim Belefic, available with FR3 fluid and ultra-low noise levels below 50 dB, are designed to meet fire safety standards, environmental regulations, and acoustic requirements—making them ideal for installations in or near populated areas.
Remote PV projects that feed weak and rural distribution networks require specially designed transformers with precisely matched parameters to reduce voltage rise at the point of grid interconnection and reduce short-circuit current.
Daelim Belefic configures its solar inverter duty transformers according to short-circuit current calculations, supplies OLTCs where voltage fluctuation is significant, and reduces the effect of potential-induced degradation in the solar power plant.
Floating solar systems and solar power plants in offshore installations combine thermal demands with extremely corrosive environments. Daelim Belefic manufactures solar inverter duty transformer variants with fully hermetically sealed corrugated tanks and marine grade C5-M coating (ISO 12944). This combines the inverter-specific electrical design in a sealed construction with reduced maintenance requirements, proven in specific offshore and marine conditions.
At Daelim Belefic, every solar inverter duty transformer project begins with precise alignment between the inverter, the solar plant’s operating characteristics, and the requirements for seamless grid integration—ensuring optimal performance from day one. The customization options for our transformers are significant:
The production of solar inverter duty transformers at Daelim belefic goes through specific checkpoints to ensure top quality products and final deliveries. Daelim belefic holds ISO 9001, CSA, CESI, CNAS, and SGS certifications with UL/cUL for applicable transformer types. At its core, the focus is on:
Before the transformer production starts, the R&D team consults with the customer and conducts a harmonic analysis according to the inverter specification. Core flux density, winding insulation grade, K-factor selection are analyzed according to the inverter and harmonic components produced by the solar power plant.
During production, we do not follow assumptions and catalog frames. The verified transformer design is documented and delivered to the customer with the unit’s test package.
In accordance with the IEC 60076 standard, each Daelim Belefic solar inverter duty transformer undergoes the following tests:
Daelim Belefic exports transformers for utility-scale projects where precision, accuracy and delivery quality are critical. Missed deadlines and commissioning dates can result in significant penalties. Over the years, our logistics support has grown and is designed to support the reality of tight deadlines and high customer expectations. Some of the specifics of our delivery are:
Daelim Belefic provides support to its customers throughout the entire asset lifecycle – from specification of characteristics, commissioning to long-term field support.
When you choose a transformer from Daelim Belefic, you can be confident it is precisely engineered to match inverter performance, site conditions, and grid connection requirements.
The result is a more efficient transformer, fewer failures and operational confidence at every stage of the project. Whether you are building a solar power plant or optimizing an existing one, the right transformer can make a measurable difference.
Are you ready to optimize your solar power plant? Request a solution tailored to your needs, consult with our expert team or download our detailed product specifications today – to ensure your system will perform exactly as you envisioned.
Standard transformers are designed for simpler consumers. Solar inverters produce higher harmonics and transient overvoltages, which standard transformers cannot handle. These processes accelerate insulation aging, increased noise and vibration, which can lead to early failure.
Yes, that’s what we do in every situation in these and similar projects. Our transformers are adaptable for SMA, Sungrow, Huawei, ABB and many other inverter platforms. After you provide all the data about the inverter, our expert team – you will receive a response within 48 hours with all the necessary data and calculations.
The choice of K-factor depends on the required performance. A moderately loaded system with THD up to 35% can use K-4. K-13 is suitable for networks where THD is up to 70%, while larger transformers can have a higher K-factor.
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