E3/DC e3dc (pv)
The E3/DC e3dc (pv) is a photovoltaic meter template for the E3/DC S10 Home Power Plant, a combined PV inverter and battery storage system. Over Modbus TCP, this template reads two holding registers: power_a at address 40067 for instantaneous PV generation power and power_b at address 40075, the high word of the grid power int32 pair. Together these registers let your ModbusCloud Gateway deliver live solar production data to the portal for dashboards, alerts, and historical trend analysis.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 2, read only
- Brand
- E3/DC
- Last updated
Registers (2)
2 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power_a | W | Read | |||
| power_b | Read |
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Use cases
- Monitor real-time PV generation from the E3/DC S10 to verify panel output against irradiance forecasts.
- Track daily solar production trends in the portal to detect module soiling or shading over time.
- Alert on unexpected drops in power_a during peak sun hours to catch inverter faults early.
- Compare PV generation against household consumption to report self-consumption ratios by day.
- Verify that power_a readings match the E3/DC app display after firmware updates or configuration changes.
Installation
Enable Modbus TCP on the E3/DC S10: navigate to the device menu under Funktionen or Smart-Funktionen, activate Modbus, then select the E3/DC protocol on port 502.
Connect the E3/DC S10 to your local network and confirm its IP address is reachable from the same LAN segment as the ModbusCloud Gateway.
In the ModbusCloud portal, add a new gateway, import the E3/DC e3dc (pv) template, and set the unit ID to 1 and the TCP port to 502.
Spot-check the power_a register in the portal live view during daylight hours and confirm the watt value matches the reading shown in the E3/DC device interface.
Things to watch for
Why does power_a always read zero even in bright sunlight?
Modbus TCP must be explicitly enabled on the S10 and the E3/DC protocol selected in the menu. If the interface is active but power_a stays zero, confirm the unit ID is set to 1 and the gateway is polling address 40067, not 40068. A one-register offset is a frequent configuration mistake across Modbus clients.
The gateway connects but no values appear in the portal. What now?
Check that the S10 IP is accessible on TCP port 502 from the Gateway network segment. Firewalls or VLANs can silently block Modbus traffic. Also verify the reconnect interval is configured: after an S10 restart the Modbus connection is not re-established automatically unless a reconnect timeout is set.
Why does power_b sometimes show very large numbers?
Power_b is the high 16-bit word of the grid power int32 pair. When the E3/DC system is exporting to the grid, this word will be 32768 or above as part of the two's-complement int32 encoding. Read the value as a signed int32 spanning both registers, not as a standalone uint16, to get the correct grid direction and magnitude.
Values look correct most of the time but jump to garbage after several hours. Why?
The E3/DC Modbus connection can time out silently. If your polling interval is very long or network interruptions occur, the S10 may drop the TCP session. Configure the ModbusCloud Gateway with a reconnect interval so connections are automatically re-established without requiring a manual portal intervention.
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