Battery storage (BESS) integration
Fronius GEN24 Plus: battery and PV under one control
Fronius, the Austrian inverter maker from Wels, puts the PV strings and the battery behind one hybrid inverter in the GEN24 Plus and the Symo Hybrid. Voltmasters EMS reads and steers that inverter over a single SunSpec Modbus TCP connection and shows the battery and the PV strings in the platform as two linked devices.
Supported devices
- Primo GEN24 Plus
- Symo GEN24 Plus
- Symo Hybrid
Fifteen hybrid models with a Fronius storage system: the single-phase Primo GEN24 Plus (3.0 to 6.0 Plus), the three-phase Symo GEN24 Plus (3.0 to 10.0 Plus) and the Symo Hybrid (3.0-3-S, 4.0-3-S and 5.0-3-S). Only the Plus variants of the GEN24 take a battery; a GEN24 without Plus is added as a Fronius PV inverter. Supported from controller version 0.0.336.
What the EMS gets out of your Fronius installation
- Trade on the imbalance market and dynamic prices, quarter hour by quarter hour
- Peak shaving: keep peak power and capacity tariff under control
- Maximise self-consumption together with PV and EV chargers
- Fluvius telecontrol and grid compliance, certification included
- Real-time monitoring with automatic incident detection
Why installers combine Fronius and Voltmasters
On its own, a hybrid inverter only decides when its battery charges. With the EMS added, it follows the strategy of the whole site: charging and discharging for self-consumption and peak shaving, charging from the grid while the EMS is steering, curtailing the PV through the output limit and controlling reactive power. When the EMS stops steering, it releases the battery, the output limit and the reactive power and restores the grid charging setting it found. The inverter then continues on its own energy management instead of staying frozen at the last setpoint.
The technical bit, in short
- Connection over SunSpec Modbus TCP, port 502, slave id 1
- Enable Modbus TCP and allow inverter control via Modbus, otherwise the inverter refuses the battery setpoints
- Fixed IP address on the same network as the controller
- Fill in the battery capacity yourself: the inverter does not report the size of the storage system
- Incidents for an inverter fault, an inverter alarm and a battery that is not connected
How it works
How your Fronius connects to the EMS
Voltmaster Controller in the cabinet
The industrial DIN-rail controller sits next to the installation and runs the optimisation locally, even without internet.
Connect over the local network
You connect the device following the step-by-step guide in our documentation. We assist with commissioning on your first project.
Configure and go live
The installation appears in the platform: dashboards, control and monitoring are active right away.
FAQ
Questions about the Fronius integration
Which Fronius inverters does Voltmasters support as a battery system?
The hybrid inverters with a Fronius storage system: the Primo GEN24 Plus (3.0 to 6.0 Plus), the Symo GEN24 Plus (3.0 to 10.0 Plus) and the Symo Hybrid (3.0-3-S, 4.0-3-S and 5.0-3-S), over SunSpec Modbus TCP. A GEN24 without Plus, or another Fronius inverter without a battery, is added as a PV inverter.
What should I watch for with the minimum reserve of the inverter?
The inverter keeps a minimum reserve of its own, which also serves as its backup power reserve, and the EMS does not change it. When that reserve sits above the minimum SoC you configure on the battery, the EMS cannot use the band between the two and raises a warning. Compare both values when you commission the site.
Does the system keep working when the internet drops?
Yes. The Voltmaster Controller runs the optimisation locally in the cabinet. If the connection drops, control, peak shaving and the safety limits simply stay active.
How do I connect a Fronius GEN24 Plus to the EMS?
The Voltmaster Controller connects to the device over the local network. The step-by-step instructions are in our documentation, and as a certified partner we guide your first commissioning from start to finish.
Sources
Manufacturer documentation
This page links to the manufacturer's own documentation for this device. Always check the most recent version at the manufacturer.
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