Running evcc in our second home with Fronius

After setting up evcc in our primary home, we wanted to do the same in our holiday home. The photovoltaic (PV) system there was installed by the home’s previous owner, and includes a Fronius Symo GEN24 inverter, a Fronius Smart Meter and a BYD battery. The other components are the same as in our primary home: evcc runs on a Synology NAS, the wallbox is a go-e Gemini and the charged vehicle is from VW. This article will therefore be short one and only cover the differences to our primary setup. So, I suggest you start by reading the previous article on the basics of the setup and then continue here if you are interested in the specifics for Fronius and other topics related to having evcc in a second home.

The diagram below shows the setup in our second home:

The remainder of this article covers the following topics:

  • Setting up a second evcc instance
  • Configure Fronius Symo GEN24
  • Create evcc configuration
  • Resolving conflicts in vehicle detection

And now, let’s dive right into the first one.

Setting up a second evcc instance

The first thing to consider when running evcc in a second home is where to host it. Each instance of evcc only supports one home (site), therefore with two homes you need two instances. If your homes are connected via a reliable VPN, you can host your second evcc instance on the same system as your first. We do not have a VPN yet, and have a Synology NAS in our second home anyway, so I decided to run the second evcc instance there. Check the previous article on how to setup evcc on Synology.

Configure Fronius Symo GEN24

The integration of the inverter works via Modbus TCP, the same protocol used for integrating the Huawei inverter in our first home. Again, I recommend assigning a static IP address to the inverter in your home router’s DHCP configuration. You can then access the local web interface of the inverter via that IP address and activate Modbus TCP. For that, you will need the “Technician” password for the inverter. If you do not have that, ask your installer to do the configuration for you or provide you with the password.

The following screenshots show the required configuration:

In the main dashboard click on Communication …

… and there on Modbus, where you’ll find the option to enable Slave as Modbus TCP. All the other options can be left to their defaults.

As alternative to Modbus TCP you can also use evcc’s integration of the Fronius’ Solar API V1. It also works via the local network, without needing any cloud connection, and has the advantage that it can be activated via a “Customer” account on the local inverter, so no need for the “Technician” account.

Create evcc configuration

After you have setup the Fronius devices as described above, and also the go-e wallbox and vehicles as described in the previous article, you can proceed with creating the evcc configuration. You can download our configuration file here.

We again created the configuration file via the “evcc configure” command described in the previous article, just selecting the “Fronius Primo GEN24 Plus” instead of the Huwaei. You only need to enter its IP address, all other values can be left to their default:

The configuration worked fine from the get-go, there was only one small issue we encountered:

Resolving conflicts in vehicle detection

Knowing which vehicle is being charged enables evcc to show the state-of-charge and provide features like charging limit and planned charge. There are three methods for identifying the vehicle connected: via charging cable (only supported by a few vehicle/charger combinations), via an RFID or other token used at the charger or via the charging status. The first doesn’t work for our go-e wallbox and also we are not using RFID tokens, which leaves only the third method. For that, evcc looks at all vehicles and their charging (connection) status to see which one is connected. In our case that works via the Volkswagen cloud service, which we already setup for our primary home. There the detection works fine, we have two vehicles and one charger. Only one vehicle can be connected at a time, so evcc can reliably determine which one that is. However, when going to our second home, we usually leave one vehicle behind and connected. Therefore when we connect the other vehicle at the second home, evcc will find that both vehicles are connected and cannot determine which one is which.

Since we always use the same, bigger vehicle for going to the second home, the solution for this is simple: I configured that vehicle as default vehicle for the loadpoint in the second home. This way evcc will always assume it is that vehicle that is connected. Only if we would use our other car, I’d have to manually switch vehicles in the evcc user interface. If we’d be using both vehicles regularly in both homes, I’d probably use the RFID tokens that came with the go-e wallbox to identify the two vehicles.

Final words

Apart from the small issue of vehicle detection, the installation and configuration of evcc again went very smooth. Again we are very happy with the benefits it brings us in making the most of our solar power. If you have any questions about our evcc setup, don’t hesitate to contact me.