Custom Home Assistant integration for Solvis Heating Devices.
Solvis GmbH is a German manufacturer of innovative and energy-efficient heating systems. The company develops hybrid heating solutions, solar panels, and heat pumps that can be flexibly combined. The Solvis Modbus interface allows seamless integration with Home Assistant for monitoring and control.
This integration provides full support for SolvisControl 3 (SC3) devices with an enabled Modbus interface, offering seamless integration with Home Assistant.
SolvisControl 2 (SC2) devices are supported with limitations. SC2 requires a SolvisRemote module for Modbus communication, and functionality is available only from firmware version MA205.
Older Solvis control units (e.g., SC1) and devices without Modbus support are not compatible.
Some features may depend on the firmware version installed on SC3. Keeping the device firmware up to date is recommended for best compatibility.
The following firmware versions are confirmed to be fully supported: 3.19.47, 3.20.05 and 3.20.16. The following versions are likely to work but are not fully verified: 3.15.09, 3.17.12. Other versions (3.5.1 and earlier) may also be compatible, but have not been tested.
The version of the network board should not be critical for the functionality of the integration. No issues have been observed so far with any of the currently used versions 3.0.1, 3.1.0, or 3.2.1.
Some features may depend on the firmware version installed on SC2. As there are some known deviations from documentation and actual firmware implementation, staying on the latest version is recommended, as the integartion is set to deal with these deviations.
The following firmware versions are confirmed to be fully supported: 205.08 (latest) Other versions may also be compatible, but have not been tested.
If you have information about the compatibility of an unlisted version, or encounter issues with a listed version, feedback is welcome.
Due to the wide range of configuration options, system versions, and occasionally unclear documentation, some entity names—especially for less common setups—may be incorrect or misleading. Less common configurations include, for example, SolvisMax district heating, separate solid fuel boilers, external boilers, swimming pool heating circuits, or solar thermal systems with east/west-oriented roof surfaces.
If you encounter such cases, we appreciate feedback including a description of the issue and details about your system configuration, so we can take it into account in future versions.
The easiest way to install this component is using the Home Assistant Community Store by clicking the badge below, which adds this repository as a custom repository to your Home Assistant instance:
- Click the Download button in the lower right corner.
- Select the recommended version.
- Restart Home Assistant.
Note on available versions: Please stay with the recommended version unless you know what you are doing!
Details
- Copy the repository contents of
custom_components/solvis_controlinto<HASS config directory>/custom_components. - Restart Home Assistant.
To use this integration, the Solvis device must have Modbus enabled.
Follow these steps
- Navigate to Sonstiges → Nutzerwechsel → Installateur and enter the default code 0064.
- Navigate to Sonstiges → Modbus → SmartHome/GLT and change Modus from Aus to write.
Notes:
- Screenshots are from Solvis SC3 (Ver. MA3.19.47).
- Selecting "read" mode only allows data monitoring, but not active control.
- It is strongly recommended to use the latest firmware version. For the SC3, the current version as of April 2025 is MA3.20.16.
SC2 devices require a Solvis Remote device for Modbus communication. To use this integration, the Solvis device must have Modbus enabled along the following steps:
Follow these steps
- Navigate to Sonstig. → Nutzerwechsel → Installateur and enter the default code 0064.
(Sonstiges)
(Remote)
(next screen)
Notes:
- Screenshots are from Solvis SC2 (Ver. MA205.08 N300), and Solvis Remote V2.20.06
- Selecting "read" mode only allows data monitoring, but not active control.
Once the integration is installed and Modbus access is enabled, add the device in Home Assistant:
- Go to Settings → Devices & Services → Integrations.
- Click Add Integration and search for Solvis Control. Click on it.
- Configure the integration:
- Assign a device name (optional).
- Enter the IP address of the Solvis Remote Device (found in your router's DHCP list).
- Keep the port unchanged.
- Select your Solvis Control version and set the low, standard and high polling intervals.
- Use the checkboxes to select which assemblies and system components (second and/or third heating circuit, heat pump, solar collector, heat meter, PV2Heat) are connected to the heating system.
- In the final step of the configuration, for each available heating circuit (as defined in the previous step), you can configure the presence and behavior of the room temperature sensor. Select 'disabled' if no sensor is installed, 'read' to only read the value (default), or 'write' if the value should be writable.
After setup, the integration polls an initial set of parameters and completes the installation with a success message.
Notes:
- The integration attempts to determine the number of existing heating circuits via Modbus query. If the automatically determined number is incorrect or a different configuration is desired, the second and third heating circuits can be manually enabled or disabled. The corresponding entities will then be (not) added accordingly.
- The integration uses three polling intervals: high, standard, and low.
- The high polling interval defaults to 10 seconds, with a minimum of 2 seconds. It is used for frequently changing values (e.g., flow temperatures).
- The standard polling interval defaults to 30 seconds, with a minimum of 2 seconds. It must be a multiple of the high interval and is used for regularly changing values (e.g., room temperature).
- The low polling interval defaults to 300 seconds, must be greater than 10 seconds, and must be a multiple of the standard interval. It is used for rarely changing values (e.g., firmware version).
- For an overview of which values are retrieved at which interval, please refer to the polling groups list
- The SC2 Processor and Modbus implementation seems to be rather slow in processing requests. As a result, the web interface responds rather sluggish with the integration running. If that poses a problem, increasing the polling intervals might reduce the issue.
This integration enables data polling and control of up to three heating circuits, solar panels, and heat pumps connected to Solvis Heating Devices via the Solvis Modbus interface.
For a detailed list of supported entities, check the supported entities list.
Notes:
- For more information on the Solvis Modbus interface, refer to:
- Official Modbus specifications are partially outdated and contain incorrect information (example for SC2 - flow meters do not provide the flow in l/sec as described, but the impulse duration of the flow meter)
- A revised SC3 Modbus specification is expected in 2025 (unofficial information from Solvis, December 2024).
- Sometimes useful for debugging: Anlagenschema SolvisMax - ALS-MAX7 Ver. 27350-2n
If you experience issues with the integration, check the following common problems and solutions.
Verify connection from Home Assistant to SC3 devices
To check if the Modbus connection is active on an SC3 device:
- Switch to Installateur mode.
- Navigate to Sonstiges → Status Modbus.
- The connection should appear under TCP server.
Note: The integration only establishes a Modbus connection briefly to poll data. Therefore, the Home Assistant IP is not permanently visible in the connection overview but appears only for short periods.
Modbus connection fails
Symptoms:
No communication between Home Assistant and the Solvis device.
Solutions:
- Ensure that Modbus is enabled in the Solvis device (
Sonstiges → Modbus → SmartHome/GLT). - Verify that the correct IP address and port number are set in the integration.
- Test the network connection (e.g., using
ping). - Check firewall or router settings for potential blocks.
Incomplete or incorrect sensor data
Symptoms:
Some sensor values are missing or show unrealistic readings.
Solutions:
- Ensure that the Solvis device runs the latest firmware version.
- Restart Home Assistant.
Integration not recognized in Home Assistant
Symptoms:
The integration does not appear in the list of available integrations.
Solutions:
- Ensure that all integration files are correctly placed under
custom_components/solvis_control. - Clear Home Assistant’s cache and restart the system.
Issues with write operations (Modbus Write)
Symptoms:
Changes (e.g., target temperatures) are not applied.
Solutions:
- Ensure that Modbus is set to
writemode instead ofread(see prerequisites). - Update the Solvis controller firmware.
Error: convert_from_registers() got an unexpected keyword argument 'word_order'
Symptoms:
The integration fails to initialize or throws errors during setup. Log message includes:
TypeError: ModbusClientMixin.convert_from_registers() got an unexpected keyword argument 'word_order'
Cause:
An incompatible version of the pymodbus library is active. This often happens when another integration (e.g., SolarEdge Modbus, Huawei, Goe) installs its own older version of pymodbus, overriding the version required by this integration.
Solutions:
- Ensure all Modbus-based integrations are updated to versions compatible with pymodbus >= 3.8.0.
- If using the SolarEdge Modbus integration, update to V2.0.3, which includes a compatible pymodbus.
- Reboot the entire Home Assistant system, not just Home Assistant Core, to ensure the correct library version is used.
If the issue persists, please provide debug logs and open an issue on GitHub.
If the issue persists, enable debug logging in Home Assistant by adding the following to your configuration.yaml:
logger:
logs:
custom_components.solvis_control: debugAfter restarting Home Assistant, check the logs under Settings → System → Logs for any error messages related to the integration.
When opening an issue on GitHub, please include:
- A clear description of the issue:
What is happening, and what did you expect? - Relevant error messages from the logs:
Copy and paste any related log entries. - Details about your setup:
- Home Assistant version
- Solvis device model
- Firmware version
- Steps to reproduce the issue:
If possible, describe how to trigger the problem.
Providing detailed information will help diagnose and resolve the issue more efficiently.
We welcome pull requests! Please allow time for review. If you need guidance on where to contribute, open a discussion — we're happy to help!
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