Fenecon Dess PvMeter
The Fenecon DESS PvMeter is a per-phase PV generation measurement component within the Fenecon DESS (Distributed Energy Storage System), managed by the FEMS energy management system on OpenEMS. Over Modbus TCP, this template reads the three-phase active power registers of the PV meter: active power on L1, L2, and L3. These values let the FEMS, and your ModbusCloud portal, track live solar generation across each phase independently. Installers monitoring DESS installations use this data to detect phase imbalance, validate PV yield, and feed generation figures into multi-source energy dashboards.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 3, read only
- Brand
- Fenecon
- Last updated
Registers (3)
3 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| active_power_l1 | W | Read | |||
| active_power_l2 | W | Read | |||
| active_power_l3 | W | Read |
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Use cases
- Monitor per-phase PV active power on L1, L2, and L3 to catch asymmetric generation early.
- Track cumulative solar yield per phase to verify string performance over days and weeks.
- Alert on a sudden drop in active power on any single phase to detect inverter or wiring faults.
- Compare L1, L2, and L3 generation values to identify persistent phase imbalance in the PV installation.
- Feed live per-phase PV power readings into a multi-site energy dashboard for portfolio reporting.
Installation
Enable the FEMS App Modbus/TCP Read Access on the FENECON DESS system via the FEMS App Center, and note the FEMS box IP address on the local network.
Connect the ModbusCloud Gateway to the same LAN as the FEMS box, ensuring TCP port 502 is reachable from the Gateway to the FEMS IP address.
In the ModbusCloud portal, add the Gateway, import the Fenecon DESS PvMeter template, and set the Modbus unit ID to 255 (the FEMS default) and the base address offset to 0.
Trigger a manual poll on register 11144 and confirm the L1 active power value matches the live PV reading shown in the FEMS Online Monitoring dashboard.
Things to watch for
All three registers return zero even when the PV system is producing.
The PvMeter component in FEMS only exposes register values when the corresponding FEMS App (PV meter integration) is active and a physical meter is connected and communicating. Verify in the FEMS App Center that the PV meter app is installed and shows no faults. A red LED on the BMS box or an error in Online Monitoring usually points to the root cause.
The Gateway connects on port 502 but reads return exception code 02.
Exception code 02 (Illegal Data Address) means the register block is not enabled for external access. By default, the FEMS Modbus/TCP interface exposes only the _sum and ess0 component channels. Access to the PvMeter component (addresses around 11144) must be explicitly enabled in your FEMS project configuration. Contact your FEMS system integrator to confirm the correct component unlock.
Register values are off by one address compared to the Fenecon documentation.
This is a known base-address offset issue. The FEMS Modbus/TCP API requires the base address to be set to 0 in your Modbus client, not 1. If your client (or the ModbusCloud Gateway profile) defaults to 1, every register will be shifted by one. Set the base address to 0 to align with the template addresses 11144, 11174, and 11204.
Values on L2 or L3 appear stuck or always read the same as L1.
Each phase register sits at a separate address spaced 30 apart: 11144 for L1, 11174 for L2, 11204 for L3. If polling returns the same value for all three, your Modbus client may be reading three consecutive 16-bit words starting at 11144 instead of polling each address individually. Configure three separate register reads, one per address, as defined in the template.
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