Infineon Technologies is supplying silicon carbide (SiC) power semiconductors to renewable energy solutions provider Fox ESS, helping the company improve the efficiency and power density of its residential energy storage systems.
The company is using Infineon’s CoolSiC™ MOSFETs 1200 V G2 in the top-side-cooled Q-DPAK package in Fox ESS energy storage systems. According to Infineon, the technology has helped Fox ESS cut switching losses by 70%.
Infineon SiC MOSFETs contributes to the performance of Fox ESS’s PQ3-Ultra energy storage system, which achieves a peak photovoltaic inverter efficiency of up to 98.78% in grid-connected operation. Its battery charge and discharge efficiency reaches up to 98.47%.
SiC technology targets efficiency and thermal performance
The CoolSiC MOSFETs are designed to address the efficiency, thermal management and power-density requirements of modern residential energy storage systems.
Infineon’s Q-DPAK package uses top-side cooling to improve thermal management while giving designers greater flexibility in PCB layout. The package is also designed to reduce parasitic effects and stray inductance compared with conventional bottom-side-cooled configurations.
The devices incorporate Infineon’s .XT interconnection technology, which helps lower thermal resistance and operating junction temperature. Their trench gate architecture is designed to reduce switching losses, supporting higher system efficiency.
The compact package also allows manufacturers to save board space while maintaining the power-handling capabilities required for energy storage applications. Its compatibility with automated assembly further supports scalable manufacturing.
Fox ESS ranks first in 10 kW hybrid ESS test
The technology partnership comes as Fox ESS reports strong results for its residential energy storage portfolio.
In a recent evaluation conducted by HTW Berlin University of Applied Sciences and AQUU Research, Fox ESS’s hybrid energy storage solution, combining the PQ-H3-Ultra-10.0 inverter with the EQ3300-5 battery, achieved a System Performance Index (SPI) of 97.0%.
The result placed Fox ESS at the top of the 10 kW class among the hybrid inverter and storage systems tested in 2026. It also represents the highest SPI score recorded since the evaluation began in 2018.
For residential energy storage manufacturers, higher conversion efficiency can translate into better utilisation of generated solar power and reduced energy losses during charging, discharging and grid interaction.
Growing global deployment
Fox ESS has expanded its residential solar and energy storage footprint significantly in recent years. Over the past three years, the company has installed more than 890,000 photovoltaic inverters and over 1 million batteries across more than 70 countries.
The collaboration with Infineon reflects the growing role of SiC power semiconductors in residential energy storage, where manufacturers are looking to combine higher efficiency with compact designs, thermal performance and reliable operation.
