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Fronius Ohmpilot FAQ


The Fronius Ohmpilot is a consumption regulator designed to use excess solar power to heat water.
Thanks to the continuously adjustable regulation from 0 to 9 kW, surplus PV current can be put to highly efficient use and fed to the loads in the household.
The Fronius Ohmpilot is primarily used to intelligently control heating elements for providing hot water in boilers and buffer storage tanks, but can also be used for infrared heating or towel radiators. Solar power can thus provide a family home with average levels of water consumption with most of their hot water during spring and summer.

The result is maximum self-consumption, a reduction in the household’s CO2 emissions and less wear on the building’s main heating system during the summer months.

To use the Ohmpilot you need a Fronius Smart Meter and a Fronius Data-/Hybridmanager or GEN24 inverter. A Data- or Hybridmanager is installed as standard in the standard version of all Fronius SnapINverters (Symo, Symo Hybrid, Primo, Galvo, Eco). You can also retrofit a Datamanager Box into any system regardless of which inverter you have.
Yes, by retrofitting a Fronius Datamanager Box 2.0 and a Fronius Smart Meter you can use the Ohmpilot with any pv system, no matter what inverter you have.
A Fronius Datamanager requires at least firmware version 3.8.1-6, a Hybridmanager at least 1.8.1-9 in order to be compatible with the Fronius Ohmpilot. GEN24 inverters require no minimum firmware version.
The heating element can be connected directly to the Ohmpilot. The communication between Ohmpilot and inverter can be established via a direct RS485 cable (Modbus RTU) or via a local network (ethernet or wifi).
Single-phase heating elements can be operated from 0.3 to 3 kW and three-phase heating elements from 0.9 to 9 kW. Use only purely resistive loads (no electronic temperature limiters, fans, ...). Three-phase heating elements must have a neutral wire connection in the star point and their load must be divided equally between all 3 phases (e.g. 3x 3kW).
You can update the firmware of your Ohmpilot on Solar.web under "Settings" - "Components".
The Ohmpilot has 2 years Fronius Warranty Plus starting from dispatch from Fronius factory. It is not possible to extent the warranty.
No, the use of several Ohmpilot in one system is not supported.
This curcuit diagram shows how it is possible to implement heating systems of more than 9 kW.

Installation & Start up

Make sure the inverter has been fully commissioned first. Once you've connected the Ohmpilot to the inverter or the same network as the inverter, within about 5 minutes the components should connect automatically with each other and the Ohmpilot will start operating. Further settings can be made on the user interface of the Ohmpilot.
Settings for the Ohmpilot can be adjusted on its user interface. Press the button on the Ohmpilot two times to activate the wifi access point, then connect to the Ohmpilot's wifi and enter the ip address in your browser's URL bar to access the user interface.
The communication between Ohmpilot and inverter can be established via a direct RS485 cable connection (Modbus RTU) or via a local network (Ethernet or WIFI).
The bus cabling is done in parallel with the Fronius Smart Meter and the Fronius inverter or Data-/Hybridmanager. Please refer to the manual for details.
The network configuration is done on the user interface of the Ohmpilot under "Network". The inverter searches for the Ohmpilot and connects automatically as soon as both components are within the same network. The search process may take up to 5 minutes. When using subnets, both components must be in the same subnet. Please refer to the manual for details.
The Ohmpilot must be equipped with a circuit breaker of maximum B16 A and a residual-current circuit breaker on the grid side.
The maximum cable length from the output of the Ohmpilot to the load (heating element) must not exceed 5 m in order to fulfill EMC standards.


When the legionella prevention system is activated, the hot water is heated up to 60 °C at a set interval. You can change the interval on the user interface of the Ohmpilot. It is not possible to set the legionella prevention to a specific day of the week or specific time of day.
The Ohmpilot starts heating at around 300 W power surplus.
Yes, the Ohmpilot has a control output for switching a heat pump. For activation, the heat pump must have a control input (e.g. SG Ready or grid operator release). Please refer to the manual for further details.


There can be several reasons, like not enough surplus energy being available. For troubleshooting, press the button on the Ohmpilot three times to activate boost mode.
If the Ohmpilot is still not heating, check the neutral wire connection, the temperature switch of the heating element and make sure you are using a compatible heating element.
If the Ohmpilot is heating during boost mode, but not during normal operation, check your maximum temperature settings and the communication between the Ohmpilot and the inverter.

Possible reasons are the legionella prevention system, your minimum temperature settings or a problem with the Smart Meter. Check your settings on the user interface of the Ohmpilot and the Smart Meter values.
After a component exchange the data connection must be restored manually. Connect to the user interface of the inverter and add the Ohmpilot to the components under "System information" (Data-/Hybridmanager) or "Device Configuration" (GEN24).
No, there are no additional, recurring checks necessary.

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