This python script simulates a SDM630 energy meter, it provides the modbus register 30053 (total system power in Watt) which the Growatt MIC 600TL-X requests over RS485 when export limitation is activated.
Usage:
./growatt_simulate_sdm630.py SERIALPORT TOTAL_SYSTEM_POWER_IN_WATT
Successfully tested with FTDI FT232 based USB-to-RS485 interface.
The export limitation works in principle, but when the total power (reported by the meter) goes above ~2kW, the inverter goes down to ~6W. Observed with Firmware: GH1.0
Other users also report this problem: https://www.photovoltaikforum.com/thread/168815-growatt-1500tlx-durch-smartmeter-steuern/?postID=2702847#post2702847
- Turn on export limit with 40% on MIC 600TL-X (menu -> advanced setting)
- Wire RS485 (signals A and B, 120 Ohm termination an both ends) and connect RS485 interface to computer
- Simulate power export of 300W:
./growatt_simulate_sdm630.py /dev/ttyUSB0 300=> OK: regulation works - Simulate power export of 2300W:
./growatt_simulate_sdm630.py /dev/ttyUSB0 2300=> FAIL: inverter power goes down to ~6W
I've contacted the Growatt support. If a solution is found, I will report here.