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.

WARNING: this repository depends on a closed source library, velib.

PV Inverter Compatibility

Fronius: All Fronius inverters supporting the solar API v1. Also the sunspec modbus TCP standard is supported. If ModbusTCP is enabled on the Fronius using the web interface, then their ModbusTCP api is used, not the JSON. Power limiting, aka Zero feed-in, only works via ModbusTCP.

ABB: both monitoring and power limiting works. Uses the ModbusTCP sunspec API.

SMA: only monitoring works. Power limiting could be done, but requires more work, as SMA doesn’t follow the Sunspec API for that. Abandoned.

Solar Edge: only monitoring works. Its not possible to enable power limiting without help or even a firmware change on Solar Edge side. See details below. Abandoned.

Other PV inverters that implement the sunspec standard might work as well.

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.

SMA sunny boy:

• The Operating State (part of the inverter model) is not supported, although the SunSpec standard specifies it as mandatory. This is a problem, because the power limiter in hub4control uses this state.
• The parameters controlling power limiting are write only (SunSpec has them read/write). This is a problem because it is impossible to retrieve their current value, for example during startup. There is a workaround possible, but it is not part of this release.

Solar Edge:

• The SE2200H - SE6000H range (HD-wave) was specifically tested, though others may work too.
• The unit id is 126.
• Only one concurrent TCP connection is allowed on port 502. Additional connections are rejected.
• The inverter publishes only the Common model and the Inverter model. This is sufficient for basic operation.
• Power limiting is not possible because the inverter does not publish model 123 (Immediate Controls).

Development & toolchain

To compile and run on a (linux) PC you will also need a QT SDK (version 4.8.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.