Cyber Security
Official Statement Regarding the Cybersecurity Issue of Hoymiles HM Microinverters
Date: July 9, 2026
Hoymiles hereby issues the following official statement regarding the cybersecurity issue related to the discontinued HM Series microinverters.
Current Products Fully Comply with the Latest EU Cybersecurity Requirements
Hoymiles' current microinverter products sold in the German market have all successfully completed cybersecurity assessments in accordance with the latest requirements of the EU Radio Equipment Directive (RED) EN 18031 and have obtained compliance recognition from internationally accredited certification bodies, including TÜV Rheinland and DEKRA, demonstrating conformity with the applicable EU regulatory requirements.
Since the mandatory implementation of RED EN 18031 on August 1, 2025, all Hoymiles microinverters exported to the European Union have been designed, developed and validated in accordance with this latest cybersecurity requirements, providing enhanced protection for both device operation and communication security.
Firmware Update Plan Confirmed, Remediation Progress on Track
Following a comprehensive technical assessment, Hoymiles has finalized a remediation plan for the cybersecurity issue affecting the legacy HM Series on the market to effectively ensure the safe operation of existing users' systems.
The security firmware is currently undergoing validation and is scheduled for official release on August 30, 2026.
The new firmware incorporates AES-128-CBC encryption to further strengthen communication security and will undergo cybersecurity assessment in accordance with RED EN 18031 prior to release.
The update is designed to address the reported cybersecurity issue while further improving the overall security and reliability of the affected products.
Information for Existing Users
To ensure the continued reliable operation of installed products, Hoymiles would like to provide the following information:
1.All installed HM Series units may continue to operate normally. Users are not required to shut down or replace their equipment.
2.A complimentary firmware update will be made available for affected HM Series products. The release is planned for August 30, 2026.
3.Users may register their product information through their distributor, or Hoymiles customer support to facilitate the firmware upgrade process.
4.Upon release, detailed upgrade instructions will be published through our official Security Advisory Portal, with full technical support provided throughout the upgrade process.
Our Commitment
Hoymiles remains committed to continuously strengthening its cybersecurity governance and compliance framework.
We will continue to comply with applicable cybersecurity regulations across global markets, further enhance the security of our products, and provide customers worldwide with safe, reliable and innovative smart energy solutions.
Hoymiles Power Electronics Inc.
July 9, 2026