In solar photovoltaic (PV) power generation systems, the transformer is an indispensable key component. With the rapid development of distributed PV and large-scale ground-mounted power plants, the differences between PV dedicated transformers and traditional ordinary distribution transformers have drawn increasing attention. As a professional power equipment supplier, Xinhong Electrical provides a detailed analysis of the main differences between the two, helping you make the right choice for your specific application.
Ordinary distribution transformer: Mainly used in urban distribution networks, industrial and civil building power distribution, stepping down high voltage (e.g., 10kV, 35kV) to low voltage levels such as 400V for end-user loads. Its operating conditions are relatively stable with small load fluctuations.
PV dedicated transformer: Specifically designed for PV power generation systems, typically installed after the inverter to step up the inverter’s low voltage (e.g., 800V, 1140V) to medium or high voltage (e.g., 10kV, 35kV) for grid connection. It must accommodate the intermittent and fluctuating nature of PV generation.
PV dedicated transformers generally have a higher low-voltage side voltage (e.g., 800V, 1000V, 1500V) to match the trend toward higher DC-side voltages of PV inverters, thereby reducing line losses. Ordinary distribution transformers typically have a standard low-voltage side of 400V (or 380V/220V). Xinhong Electrical manufactures PV transformers that can flexibly match different inverter output voltages and support non-standard customization.
PV inverters generate certain harmonics (mainly 3rd, 5th, and 7th orders) and small DC components during operation. Ordinary distribution transformers are not designed with these special components in mind, and prolonged operation may lead to core saturation, increased noise, and local overheating. In contrast, PV dedicated transformers adopt optimized magnetic circuit designs (e.g., lower magnetic flux density, higher insulation levels) and use low-loss, high-permeability magnetic materials to effectively suppress harmonic effects and prevent magnetic saturation caused by DC bias.
Ordinary distribution transformer: Commonly uses Dyn11 or Yyn0 connection groups, with short-circuit impedance generally between 4% and 6%.
PV dedicated transformer: Prefers the Dyn11 connection group, which provides a zero-sequence current path and facilitates single-phase ground fault protection. To limit short-circuit current and improve system stability, the short-circuit impedance is typically designed higher (6% to 8%) to accommodate multiple parallel-connected transformers in PV plants.
PV power plants have limited annual operating hours (approximately 1,000–2,000 hours/year) and operate at no load for long periods at night. Therefore, PV dedicated transformers have extremely strict requirements for no-load losses (core losses). They generally use high-quality cold-rolled silicon steel or amorphous alloy cores to reduce standby losses at night. Ordinary distribution transformers focus more on the overall economy of load losses. Xinhong Electrical’s PV dedicated transformers meet energy efficiency class 1 (GB 20052-2020) and even higher ultra-low loss standards.
PV systems are affected by weather conditions and may experience short-term over-generation or inverter overload. PV dedicated transformers typically have a continuous overload capability of 1.1 to 1.2 times the rated capacity, with enhanced cooling structures (e.g., larger cooling fins, forced air cooling). Ordinary distribution transformers have a relatively conservative overload capability, and prolonged overload can accelerate insulation aging.
PV power plants are often located in harsh environments such as deserts, Gobi areas, rooftops, and lake surfaces. PV dedicated transformers generally adopt fully sealed structures (e.g., corrugated tanks or expandable radiators) with protection ratings up to IP65 (outdoor type) or higher, offering moisture resistance, dust resistance, salt fog resistance, and UV resistance. Ordinary distribution transformers are typically used indoors or in semi-outdoor locations, with protection ratings usually between IP20 and IP44.
To cope with voltage fluctuations and harmonic heating in PV systems, PV dedicated transformers typically have their insulation class upgraded to Class H (180°C) or even Class C, allowing higher temperature rise limits (e.g., 125K or 150K). Ordinary distribution transformers generally use Class B or Class F insulation (temperature rise limits of 80K–100K).
| Parameter | Ordinary Distribution Transformer | PV Dedicated Transformer (Xinhong Electrical) |
|---|---|---|
| Low-voltage side voltage | 400V / 690V | 800V / 1000V / 1500V |
| Connection group | Dyn11 / Yyn0 | Dyn11 (standard) |
| Short-circuit impedance | 4% – 6% | 6% – 8% |
| No-load loss | Conventional level | Ultra-low (amorphous alloy optional) |
| Overload capacity | 1.05x short-term | 1.1 – 1.2x continuous |
| Insulation class | Class B / F | Class H and above |
| Protection construction | Standard oil-immersed sealed | Fully sealed, anti-corrosion, weather-resistant |
| Typical applications | Distribution networks, factories, buildings | PV power plants, inverter step-up |
As an experienced transformer manufacturer, Xinhong Electrical offers a full range of PV dedicated step-up transformers with capacities from 100kVA to 25MVA and voltage levels covering 11kV, 20kV, and 35kV. Our products can also be customized according to IEC standards. They have been widely used in many large-scale PV power plants both domestically and internationally, featuring high efficiency, high reliability, and long service life. For selection guidance or technical consultation, please contact the Xinhong Electrical team.
