Solar inverters are one of the fastest-growing applications for power magnetics. Whether string inverters, microinverters or central inverters, the magnetic components—boost inductors, isolation transformers, filter chokes and current sensors—directly determine efficiency, reliability and cost.
This guide covers the key magnetic components in solar inverters and their design requirements.
Shaanxi SiRui Technology Co., Ltd. manufactures boost inductors, isolation transformers, common mode chokes and current sensors for solar inverter applications. Contact: sales@sirui-tech.com | Web: www.sirui-tech.com
1. Solar Inverter Topology
A typical string inverter has two power stages: a DC/DC boost stage (raising panel voltage to the DC bus) and a DC/AC inverter stage (converting to grid-tied AC). Each stage has its own magnetic components.
2. Key Magnetic Components
Boost Inductor (DC/DC Stage)
The largest magnetic component. Handles high DC current (10–50 A) at high switching frequency (20–100 kHz). Powder core (Sendust, MPP, High Flux) is standard for stable performance under DC bias.
Isolation Transformer
Modern string inverters are often transformerless for higher efficiency, but microinverters and some string inverters use high-frequency isolation transformers for safety (4 kV+ isolation).
LCL Grid Filter
Reduces switching ripple current fed to the grid. Inverter-side inductor, grid-side inductor and filter capacitor.
Common Mode Choke
Reduces common mode noise and leakage current to meet grid standards (VDE 0126, IEEE 1547). Nanocrystalline CMCs are preferred for low leakage current.
3. Design Challenges
- Efficiency: targets 97–99%; every 0.1% matters for LCOE
- Wide input range: panels produce 200–600 V depending on conditions
- Grid standards: low leakage current (<300 mA), anti-islanding
- Outdoor reliability: 20–25 year lifetime, temperature cycling
4. Magnetics Selection
| Component | Core Material | Typical Value |
|---|---|---|
| Boost inductor | Powder core (Sendust/MPP) | 100–1000 μH |
| Isolation transformer | Ferrite (PC95/PC44) | Per voltage ratio |
| LCL filter inductor | Powder core / iron | 1–10 mH |
| Common mode choke | Nanocrystalline / ferrite | 1–100 mH |
5. Sirui-Tech Solar Products
- Boost inductors: powder core, for 1–50 kW inverters
- Isolation transformers: high-frequency, high isolation
- Grid side filter chokes: LCL filter inductors
- Common mode chokes: nanocrystalline for low leakage current
Conclusion
Solar inverters demand high-efficiency, high-reliability magnetics across a wide operating range. Powder cores are preferred for inductors due to stable DC bias performance. Nanocrystalline CMCs help meet leakage current requirements.
Need magnetics for your solar inverter? Contact Sirui-Tech at sales@sirui-tech.com with your inverter power and voltage range.