M-TEC Energy Butler GEN3 (grid)
The M-TEC Energy Butler GEN3 is an all-in-one hybrid inverter and battery storage system, available from 6 to 20 kW with stackable LFP modules from 7.7 to 30.7 kWh. This template targets the grid measurement role, reading the signed grid exchange power at register 11000 over Modbus TCP via the device's onboard Wi-Fi gateway. A positive value indicates power drawn from the grid; a negative value indicates export. Connecting the ModbusCloud Gateway to the Energy Butler GEN3 gives installers a reliable, cloud-based view of grid power flow without additional metering hardware.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 1, read only
- Brand
- M-TEC
- Last updated
Registers (1)
1 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read |
Loading registers…
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Use cases
- Monitor real-time grid import and export power to verify self-consumption performance of the Energy Butler GEN3.
- Alert on sustained grid import above a threshold to detect battery or inverter faults during daylight hours.
- Track grid exchange power trends over time to report on feed-in volumes for billing or incentive programs.
- Compare grid power readings against expected PV output to spot configuration mismatches or shading issues.
- Verify that grid export drops to zero when a feed-in limit is active on the Energy Butler GEN3.
Installation
Confirm the Energy Butler GEN3 is connected to your local network via its onboard Wi-Fi or LAN port and note its IP address, visible as the 'espressif' device in your router's device list.
Connect the ModbusCloud Gateway to the same LAN segment as the Energy Butler GEN3, ensuring both devices can reach each other on TCP port 502 (firmware 27.52.4.0 or newer) or port 5743 (older firmware).
In the ModbusCloud portal, add a new device, import the M-TEC Energy Butler GEN3 (grid) template, and set the unit ID to 247 and the target IP address to the inverter's local address.
Spot-check register 11000 in the portal's live register view: with the site drawing from the grid, the value should be a positive integer in watts; confirm the sign matches expected grid direction.
Things to watch for
The gateway connects but register 11000 always times out. Why?
The M-TEC Energy Butler GEN3 changed its Modbus TCP port from 5743 to 502 starting with firmware version 27.52.4.0. Check which firmware your unit runs, then set the portal's port field accordingly. Also confirm the unit ID is 247, not the default 1.
Register 11000 returns a value, but the sign seems inverted. What is correct?
The register is a signed int32. A positive value means the site is importing power from the grid; a negative value means it is exporting. Some third-party tools apply a scale of -1 to flip the convention. In ModbusCloud the raw signed value is preserved: positive = import, negative = export.
I get no response at all, even though the inverter is online. What should I check?
The M-TEC Energy Butler GEN3 internally uses RTU framing over TCP, not standard Modbus TCP framing. Ensure the ModbusCloud Gateway is configured for RTU-over-TCP mode. Additionally, the inverter's own cloud polling can temporarily block external Modbus queries; a brief retry interval of at least two seconds is recommended.
The gateway shows constant zero watts even during peak solar hours. Why?
A reading of zero at register 11000 often means the inverter is in island or standby mode, or that the smart meter connected to the Energy Butler GEN3 is not reporting correctly. Verify the inverter's own display shows a non-zero grid value, and check that the meter on the EMS bus is active and communicating.
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