dbus-fronius

This application communicates with Fronius, ABB, SolarEdge, SMA, and possibly also other brands of PV Inverters. The data is then made available on D-Bus, the internal Data bus in Venus OS.

The Venus OS gui application contains several pages to change the behaviour of this application, especially settings on how to detect the inverters on the LAN.

In order to build the application, you need a linux system, a recent version of QT creator, the Venus OS SDK and a not publicly available library called velib.

You can find the SDK here:

https://github.com/victronenergy/venus/wiki

The there linked documentation also contains information on how to configure QT creator to use the cross compiler that comes with the SDK.

Next you can load the project file software/dbus-fronius.pro in QT creator and create the binary.

PV Inverter Compatibility

Fronius

All Fronius inverters supporting the solar API v1 are supported and work out of the box, once properly commissioned. For now, this also includes really old models like the IG plus.

The sunspec modbus TCP standard is supported. If ModbusTCP is enabled during commissioning, then the ModbusTCP api is used instead of SolarAPI. Power limiting only works via ModbusTCP.

It is recommended that the SunSpec api is used whenever possible. It is faster, and there are less problems with correctly detecting the number of phases.

Users of GEN24 models are advised to always turn on SunSpec. This is because without SunSpec support, it is impossible to distinguish between a GEN24 and a Tauro.

ABB

Monitoring and power limiting works automatically. The ModbusTCP sunspec API is used.

SMA

Power limiting works for newer inverters, but has to be explicitly enabled on the GX device. Older Sunnyboy inverters were not tested, but can be monitored. The limiting implementation is SMA specific and not Sunspec compliant, because SMA doesn't allow cyclic writing of WMaxLimEna. SMA inverters need to be configured manually to allow limiting through modbus.

Solar Edge

All models can be monitored. Limiting is supported for some models. SolarEdge's proprietary modbus protocol is used to do limiting, where supported.

• The SE2200H - SE6000H range (HD-wave) was specifically tested.
• Some models allow only one concurrent TCP connection on port 502. Additional connections are rejected.
• US models currently lack Frequency Control, and are therefore not compatible.
• The UnitId is 126.

For limiting support:

• For SetApp (screenless) inverters: Firmware 4.8.24 or higher is required.
• For LCD inverters: Firmware 3.25xx or higher is required.

Other PV inverters

PV inverters that implement at least sunspec information models 1, 101 or 103, and 120, might work as well. Limiting support is only available if information models 123 or 704 are implemented. Limiting has to be explicitly enabled on the GX device.

Note that as the code is now, it assumes that the sunspec registers are available at unit ID 126. There is currently no mechanism to change this for the user, nor auto detection. This means that for some brands it might be necessary to change the config in the PV Inverter to that unit ID.

More information in the CCGX manual, section PV Inverter monitoring, as well as the PV Inverter manuals linked from there.

Sunspec quirks & more compatibility details

Fronius: The Fronius inverter appears to be compliant with the sunspec standard regarding the registers needed in this project. However, there may be multiple PV inverters sharing a single IP address. Multiple inverters are connected to a data manager, and not directly to the network. The data manager is connected to the network, and acts as a gateway for modbus TCP communication. Each inverter has its own unit ID. The unit IDs are retrieved using the solar API.

Development & toolchain

To compile and run on a (linux) PC you will also need a QT SDK (version 6.6.x), including QT D-Bus support. Because you do not have access to the system D-Bus (unless you run as root or adjust the D-Bus configuration) you should start the fronius application with: 'dbus-fronius --dbus session' Note that QT for windows does not support D-Bus, so you cannot build a windows executable.

The dbus-fronius executable expects the CCGX settings manager (localsettings) to be running. localsettings is available on github:

https://github.com/victronenergy/localsettings

The README.md of localsettings contains some information on how to run localsettings on your PC.

Unit tests

In order to run the unit tests, you need to install a python interpreter (v2.7 or newer).

Architecture

The application consists of 3 layers:

• Data acquisition layer:
  • FroniusSolarAPI implements the http+json protocol used to extract data from the inverters.
  • ModbusTcpClient used to communicate with SunSpec PV inverters.
  • InverterGateway is reponsible for device detection. This actual detection is delegated to one of the AbstractDetector classes. There is one for the Solar API (SolarApiDetector), and one for SunSpec (SunspecDetector). PV inverters are found by sending Solar API/ Modbus requests out to all IP addresses in the network (the maximum number of IP addresses is limited). IP addresses where a PV inverter has already been detected take priority. This is a tedious procedure which causes a lot of network travel. However, it is necessary for auto detection, because the inverters do not support any protocol for efficient detection (like upnp).
  • InverterMediator Each mediator represents a PV inverter found while the service is running. If a inverter is detected by a InverterGateway, the mediator will know whether the detected inverter is the one he represents. It is reponsible for creating and removing Inverter objects which publishes the inverter data on the D-Bus, and for starting/stopping communication with the inverters.
  • DBusFronius Ties everything together. It creates 2 inverter InverteGateway objects for device detection. If a device is found, it will create an InverterMediator if there is no mediator yet which represents the inverter. DBusFronius will also publish the com.victronenergy.fronius service.
• Data model
  • Settings Persistent inverter independent settings (stored on com.victronenergy.settings), such as the list of IP addresses where data cards have been found. This class takes the relevant data from the D-Bus using VeQItems.
  • InverterSettings Persistent inverter settings.
  • Inverter contains all values published on the D-Bus.