SolarMax SolarMax SMT (pv)
The SolarMax SMT is an on-grid transformerless PV string inverter in the 6 to 16 kW class, designed for commercial and industrial rooftop installations. This Modbus TCP template reads two core registers from the SolarMax SMT: current AC output power and cumulative total energy yield. Both registers are polled via function code 3 over a standard TCP connection, giving your ModbusCloud Gateway a live production feed and a long-term yield counter in a single import. Installers and asset managers can track generation in real time and export historical yield data without any additional hardware.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 2, read only
- Brand
- SolarMax
- Last updated
Registers (2)
2 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| energy | Wh | Read |
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Use cases
- Monitor live AC output power of the SolarMax SMT to detect shading or soiling events during daylight hours.
- Track cumulative energy yield over months to verify performance guarantees and identify degradation trends.
- Alert on zero-power readings during expected production hours to catch inverter faults or grid disconnections early.
- Compare daily energy totals across multiple SolarMax SMT units on a multi-roof site from a single dashboard.
- Report monthly yield figures from the energy register to building owners for billing or subsidy reconciliation.
Installation
Enable Modbus TCP on the SolarMax SMT via the inverter display or MaxLink App under the communication or Modbus section, and note the assigned unit ID and TCP port.
Connect the SolarMax SMT to the same local network as the ModbusCloud Gateway using an Ethernet cable, ensuring the inverter has a static or reserved IP address.
In the ModbusCloud portal, add a new device, select the SolarMax SMT (pv) template, and enter the inverter IP address, port, and unit ID assigned in step 1.
Verify the connection by checking that the power and energy registers return non-zero values during daylight; a zero power reading at midday indicates a unit ID or IP mismatch.
Things to watch for
Why does the power register return zero during the day?
The SolarMax SMT powers its communication electronics from the PV generator. If irradiance is very low or the inverter has not yet started feeding the grid, the Modbus interface is inactive and all registers return zero. This is normal behaviour at dawn and dusk. Confirm the inverter display shows active grid feed before troubleshooting further.
Values are ten times higher than the actual output. What is wrong?
Community reports confirm that some SolarMax SMT firmware versions return the power register value in units of 0.1 W rather than 1 W. If your readings are a factor of ten too high, apply a scale factor of 0.1 to the power register in your ModbusCloud portal channel configuration. The energy register is not affected by this scaling issue.
The gateway connects but no register values appear at all.
Check that the unit ID configured in the portal matches the Modbus slave address set on the inverter. SolarMax SMT units can be assigned addresses between 1 and 249. A mismatch causes the inverter to silently ignore requests. Also confirm the TCP port matches the value configured in the inverter communication settings.
Can I write to any register on this inverter via this template?
This template contains only read registers. No write access is defined, so no setpoints or control commands are sent to the inverter. If you configure any write operations outside this template, proceed with caution, as unauthorised writes to inverter registers can affect grid-feed behaviour and may affect your warranty.
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