Fronius

The Fronius integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] polls a Fronius solar inverter or datalogger for details of a Fronius SolarNet setup and integrate it in your Home Assistant installation.

Supported devices

The integration supports all inverters with integrated Datamanager or external “Datalogger Web” providing the Fronius SolarAPI (JSON) interface of version v0 or v1. This includes among others:

• Agilo
• Eco
• Galvo
• Gen24
• IG Plus
• Primo
• Symo
• Symo Hybrid
• Tauro
• Verto (Plus)

Devices connected to those inverters or dataloggers are supported as well.

• Energy meter (Fronius Smart Meter or S0 meter connected to the inverter)
• Ohmpilot
• Storage

Prerequisites

You should either set a static IP or assign a static DHCP lease for the Fronius device, or alternatively access it through the local DNS name if your network is configured accordingly.

Configuration

Configuration

To add the Fronius hub to your Home Assistant instance, use this My button:

Fronius can be auto-discovered by Home Assistant. If an instance was found, it will be shown as Discovered. You can then set it up right away.

Monitored data

Each device adds a set of sensors to Home Assistant.

• SolarNet device

  • Logger information

    General information about the Fronius Datalogger. Not available on “Gen24” devices. Updated every hour.

    • Serial number, software and hardware platforms
    • Current price of energy consumed and returned to grid and the CO₂ factor as set in the Dataloggers settings

  • Power flow

    Cumulative data of the SolarNet system. Updated every 10 seconds.

    • Energy produced on the current day, year and total produced energy
    • Power fed to the grid (if positive) or consumed from the grid (if negative)
    • Power load as a generator (if positive) or consumer (if negative)
    • Battery charging power (if positive) or discharging power (if negative)
    • Whether the battery is in standby, on Gen24 devices with a battery
    • Whether the system is currently supplying backup power during a grid outage, on Gen24, Tauro, and Verto devices with backup power configured
    • Photovoltaic production
    • Current relative self-consumption of produced energy
    • Current relative autonomy

• Inverter

  The energy produced on the current day, year (not for Gen24 devices), and total produced energy, power, current, voltage, frequency, and status for an individual inverter. Updated every minute.

• Meter

  Detailed information about power, current, and voltage, if supported, split among the phases. Updated every minute.

• Ohmpilot

  Detailed information about energy, power, and temperature of your Ohmpilots. Updated every minute.

• Storage

  Detailed information about current, voltage, state, cycle count, capacity and more about installed batteries. Updated every minute.

When an endpoint is not responding correctly the update interval will increase to 10 minutes (3 minutes for power flow) until valid data is received again. This reduces the number of requests to Fronius devices using night mode (shutdown when no PV power is produced).

Modbus TCP

Most Fronius devices also provide a Modbus TCP interface using the SunSpec information models. It exposes per-string (MPP tracker) data that the Solar API does not, so the integration reads it in addition when it is available.

Modbus is optional. If it isn’t enabled, or the inverter is powered down, no Modbus entities are created and the rest of the integration is unaffected. The integration checks again every hour, so entities appear on their own once the device answers.

To enable it on the device’s web interface:

• Gen24, Tauro, and Verto: go to Communication > Modbus and turn on the Modbus TCP server.
• Devices with a Datamanager: go to Settings > Modbus and set Data output via Modbus to TCP. One Datamanager serves every inverter in its SolarNet ring.

These entities are added per inverter and updated every minute:

• MPPT <n> DC power and MPPT <n> energy for each MPP tracker.
• MPPT <n> DC current and MPPT <n> DC voltage for each MPP tracker. Disabled by default.
• PV energy total: lifetime energy from the photovoltaic strings only. Whether this is a DC measurement depends on the device, see below.
• Battery charging energy total and Battery discharging energy total: on hybrid inverters that expose their battery as dedicated MPP trackers, such as Gen24 with a battery.

MPPT <n> DC power is a DC measurement on every device tested, and matches MPPT <n> DC current times MPPT <n> DC voltage.

MPPT <n> energy is not consistent between devices, which is why its name does not claim a side. A Gen24 reports the lifetime energy of each string, which is a DC value and therefore a few percent above Total energy, the AC counter. A SnapINverter reports the same value as Total energy instead, so PV energy total matches it exactly rather than adding anything. Comparing the two entities on your own system shows which the inverter provides.

Controlling the inverter over Modbus

Modbus is the only interface that lets Home Assistant change settings on the inverter; the Solar API is read-only. These setpoints are added as number entities, and appear under Configuration on the inverter’s device page:

• AC power limit: caps the power the inverter puts out on AC, as a percentage of its nominal power output. This is not a feed-in limit. Everything the inverter delivers counts against it, whether it is used in the house or exported to the grid.
• Battery charge power limit and Battery discharge power limit: cap how fast the battery may charge or discharge, as a percentage of its maximum rate.
• Battery minimum reserve: the state of charge the battery is not discharged below.

The AC power limit, Battery charge power limit, and Battery discharge power limit setpoints each have a switch that turns the limit on and off: AC power limiting, Battery charge power limiting, and Battery discharge power limiting. Battery grid charging is a separate switch that allows or prevents charging the battery from the grid.

A setpoint is only applied while its switch is on. Setting one while the switch is off stores the value on the inverter without applying it, and turning the switch on then applies what is stored, which is the order Fronius documents.

Turning a limit off does not lift it. The inverter hands control back to the next source in its priority list, which may impose a limit of its own, such as Dynamic power reduction. To override such a source instead, leave the limit on and set it to 100 %. That is an active instruction to run unrestricted, where off is “someone else decides”.

The inverter decides which control source wins. If IO control or Dynamic power reduction has a higher priority than Modbus in the DNO Editor, the inverter may refuse or ignore what Home Assistant sends.

Depending on the inverter’s firmware, an AC power limit below 10 % may force the inverter into standby, stopping feed-in altogether rather than throttling it.

On a hybrid inverter, the AC power limit does not restrict charging the battery. Charging is not AC output. Surplus photovoltaic power goes into the battery instead of being wasted, which makes the limit useful for peak shaving. Discharging does count against it, because that power leaves the inverter on AC.

The battery limits are power, not a charge level

Battery charge power limit limits charging power. It is not a “charge to 80 %” setting. The inverter exposes no maximum state of charge over Modbus at all; only the minimum reserve.

A charge ceiling can be built as an automation instead, using the battery’s state of charge sensor and the charge power limit:

automation:
  - alias: "Stop charging the battery at 80%"
    triggers:
      - trigger: numeric_state
        entity_id: sensor.byd_battery_box_premium_hv_state_of_charge
        above: 80
    actions:
      - action: number.set_value
        target:
          entity_id: number.gen24_battery_charge_power_limit
        data:
          value: 0
  - alias: "Allow charging the battery again below 75%"
    triggers:
      - trigger: numeric_state
        entity_id: sensor.byd_battery_box_premium_hv_state_of_charge
        below: 75
    actions:
      - action: number.set_value
        target:
          entity_id: number.gen24_battery_charge_power_limit
        data:
          value: 100

Battery charge power limiting has to be on for this to take effect. Discharging is limited by its own setpoint, so the battery still supplies the house while charging is held at 0 %. If Home Assistant stops running, the inverter keeps the last setpoint and switch state until you change them again.

Energy dashboard

Recommended energy dashboard configuration:

• For “Solar production”:
  • If no battery is connected to an inverter: Add each inverters Energy total entity.
  • If a battery is connected to an inverter: Use Riemann sum over SolarNet Power photovoltaics entity.
• “Battery systems” energy values aren’t supported directly by the Solar API. Use Riemann sum to integrate SolarNet Power battery charge and SolarNet Power battery discharge into energy values (kWh).
• For “Devices” use the Ohmpilots Energy consumed entity.

The energy meter integrated with Fronius devices can be installed (and configured) in two different installation positions: “feed in path” (grid interconnection point) or “consumption path”.

Feed in path meter

Recommended energy dashboard configuration for meter location in feed in path:

• For “Grid consumption” use the meters Energy real consumed entity.
• For “Return to grid” use the meters Energy real produced entity.

Consumption path meter

Recommended energy dashboard configuration for meter location in consumption path:

1. Use Riemann sum to integrate SolarNet Power grid import and SolarNet Power grid export entities into energy values (Wh or kWh).
2. Use these energy entities for Grid consumption and Return to grid in the energy dashboard configuration.

Example automation

The following automationAutomations in Home Assistant allow you to automatically respond to things that happen in and around your home. [Learn more] toggles a switch when the solar production crosses certain thresholds:

description: "Turn on switch when PV power is above 1000 W and turn it off below 50 W."
mode: single
triggers:
  - trigger: state
    entity_id:
      - sensor.solarnet_power_photovoltaics
conditions: []
actions:
  - choose:
      - conditions:
          - condition: numeric_state
            entity_id: sensor.solarnet_power_photovoltaics
            above: 1000
        sequence:
          - action: switch.turn_on
            metadata: {}
            data: {}
            target:
              entity_id: switch.swtest
      - conditions:
          - condition: numeric_state
            entity_id: sensor.solarnet_power_photovoltaics
            below: 50
        sequence:
          - action: switch.turn_off
            metadata: {}
            data: {}
            target:
              entity_id: switch.swtest

Note

Fronius often provides firmware updates for the datamanager interfaces and the devices in their system, it’s recommended to check and apply them regularly. This integration relies on functionality present in rather recent firmware.

Known limitations

The Solar API is read-only, so everything this integration changes on a device goes over Modbus TCP, and only what the SunSpec models expose: the output power limit and the battery charge, discharge, and reserve setpoints. Every setpoint is a percentage. Fronius exposes no absolute watt setting, and no maximum state of charge.

Details about Modbus registers can be found in the device documentation or at the Fronius website.

Troubleshooting

Can’t set up the device

• Make sure the device is not in a power-saving mode when currently not producing energy.
• Make sure the device is connected to the network and is reachable from the Home Assistant instance.
• Check the device’s settings to ensure that the Solar API is enabled.

Some devices are missing after setup or restart of Home Assistant

• Make sure inverters are not in a power-saving mode when currently not producing energy - or wait until they start producing energy.

Some entities are missing after setup

Some data, like photovoltaic production, is only provided by the Fronius device when non-zero. When the integration is added at night, there might be no entities added providing photovoltaic related data. Entities will be added on sunrise, when the Fronius devices begin to provide more data.

No power limit or battery setpoints

These are the number entities described under Modbus TCP.

• Check that Inverter control via Modbus is enabled on the device’s web interface, under the same Modbus settings where Modbus TCP is turned on. Without it the inverter rejects every write, so the integration doesn’t offer the entities.
• Reload the integration after changing the setting.

No MPPT, PV energy, or battery energy entities

These come from the device’s Modbus TCP interface.

• Check that Modbus TCP is enabled on the device’s web interface.
• Check that the Modbus port configured in Home Assistant matches the device. Reconfigure the integration to change it.
• Make sure the inverter is not in a power-saving mode. An inverter that is powered down doesn’t answer, and the entities are added once it wakes up.

Removing the integration

This integration can be removed by following these steps:

To remove an integration instance from Home Assistant

1. Go to Settings > Devices & services and select the integration card.
2. From the list of devices, select the integration instance you want to remove.
3. Next to the entry, select the three dots menu. Then, select Delete.