As demand for green hydrogen toward carbon neutrality expands, power electronics for water electrolysis systems are simultaneously required to scale up to the MW class and achieve higher efficiency. Power converters, which provide stable supply of power from renewable energy to water electrolysis stacks, are core components that influence the overall efficiency and cost of the system, and the adoption of wide bandgap semiconductors, centered on SiC (Silicon Carbide), is accelerating.
Green hydrogen is produced through a CO₂-neutral electrolysis process. Renewable energy power (wind/solar) is input into an electrolyzer to decompose water into hydrogen and oxygen. Electrolyzers require power systems to convert AC power from the grid or renewable energy generation into controlled DC current, and the performance of this converter stage directly impacts the system's OPEX (operating expenditure) and CAPEX (capital expenditure). The cost structure of green hydrogen and its price gap versus grey hydrogen are organized in Green Hydrogen Cost Trends 2026; this article focuses on the power-conversion stage that shapes that production cost.
AC/DC Converter (PFC Stage)
Converts grid AC power to DC while performing power factor correction. Compliance with grid codes and harmonic suppression are essential. High-frequency operation using SiC contributes to improved efficiency.
DC/DC Converter (Stack Drive)
Converts to the operating voltage of the electrolysis stack (several tens of V to several hundred V). Addressing low-voltage, high-current characteristics is a design challenge.
MW-Class System Support
MW-level power processing is required for large-scale green hydrogen projects. High-voltage PIMs and module paralleling are employed.
Grid Code Requirements
Renewable energy grid interconnection regulations are tightening in both Europe and North America. Compliance with power factor, harmonics, and FRT (Fault Ride Through) is a design prerequisite.
Technical Requirements for Power Conversion for Water Electrolysis
Electrolyzers are responsible for converting input power into controlled DC current. Electrolysis stacks generally operate at low voltages (around several tens of V to 200V) and high currents, and a two-stage configuration consisting of a PFC stage and a DC/DC stage is the standard design.
onsemi positions SiC power semiconductors for water electrolysis and offers high-voltage PIMs (Power Integrated Modules) for MW-class water electrolysis. Adoption of SiC enables operation at high switching frequencies, realizing miniaturization of passive components and improvement in system efficiency. In high-voltage, high-current water electrolysis systems, loss reduction directly impacts operating expenditure (OPEX), making the TCO (Total Cost of Ownership) advantage of SiC particularly prominent.
Infineon provides a one-stop power conversion solution for water electrolysis, appealing for reductions in both OPEX and CAPEX. Its ecosystem, which integrates power modules, gate drivers, and control ICs, achieves both a reduction in design man-hours and assurance of reliability.
Grid Codes and Interconnection Requirements
Power systems for water electrolysis must comply with grid code requirements. In Europe, compliance with power factor requirements, harmonic regulations, and FRT (Fault Ride Through) based on the European Network Code is required. For MW-class systems, LCL filter design for harmonic suppression and stable control of the 3-phase PFC stage are critical design challenges.
While power semiconductors are used to control a wide range of electrical equipment including automotive, industrial, power, railway, and home appliances (METI), water electrolysis applications specifically premise long-duration, high-load operation, making thermal design and assurance of long-term reliability top priorities for selection.
Implications for Procurement and Design Personnel
In power converter procurement for large-scale green hydrogen projects, onsemi (EliteSiC, high-voltage PIM) and Infineon (SiC MOSFET modules, integrated gate drivers) are positioned as key suppliers.
In MW-class systems, paralleling design of individual modules and balancing control become implementation challenges. Although the unit price of SiC devices is higher than that of IGBTs, OPEX reduction through improved conversion efficiency and CAPEX reduction through reduced passive components due to higher frequencies can be expected, making TCO-based economic evaluation the axis of procurement decisions. Since grid code compliance varies by region, it is necessary to note that design specifications diverge for Europe (EN compliant) and North America (IEEE 1547 compliant).