Correction to Solax-Growatt integration: Growatt MIN-inverters now have functional VPP registers, and do not need TOU programming

[nholmgaard]

... whereas the EMS registers and the total energy counters, which are automatically detected inserted, are by default disabled by the Solax-Growatt integration. I do not know if they can be programmatically enabled?

This would make it easier to install and take up the integration, which looks very promising indeed!

[johanzander]

I was not aware that growatt-min could support VPP, but indeed promising.
I just finished a long beta period with a few ppl that tried out the TOU method.

There is theoretical support for solax modbus, which has never been tested though, so should be fairly straightforward.

Would you be open to contribute or test it?

[nholmgaard]

I made a (very small) contribution to get VPP functional, and can confirm that it works just fine on my MIN3600TL-XH via wired Modbus.

Yes, I am trying BESS out right now, and will be happy to report back. I have gotten the EMS registers enabled and all green in the Settings, but no real usage - still showing "Initializing system". I will take a look tomorrow and let you know.

[johanzander]

Great!

There is an export debug log function in BESS which is very handy for debugging!

[nholmgaard]

I have some problems getting BESS to sell energy from the battery. The intent switch seems well intended, but does not cause the battery to discharge - Grid First is apparently not enough. Did the beta testers have batteries? I took over manually this evening using VPP to ensure that the battery was selling energy in the peak hours. I can provide scripts for controlling the battery via VPP, if you are interested.

[johanzander]

I have only had two beta testers and they both have batteries but don't know if they have explicitly verified exporting works or was happy with the arbitrage.

So please export debug logs from Bess which will give me your configuration and the VPP commands and I can have a look at it

[johanzander]

FYI: https://github.com/user-attachments/files/18301858/2.1.GROWATT.VPP.COMMUNICATION.PROTOCOL.OF.INVERTER_V2.01.pdf

[johanzander]

@jdungen - you use growatt modbus solax right? would you be interested in taking a stab at this one?

[jdungen]

Yes for sure. But I use tuo with the 3 options load,grid and battery.

[johanzander]

I guess this approach would make the tou usage for growatt solax redundant, and make the setup easier. Do you see a benefit with that?

[jdungen]

Yes Sure, will look into that doc. I have the 3PH MID 15KTL3-XH inverter with 30KW battery. (No PV as you already no) what can I test ?Thanks, Jan

[jdungen]

Did some research:

# Growatt MID 15KTL3-XH — VPP Priority Control via Modbus
#
# There is no single "mode" register. Priority behavior is derived
# from three control levers written to the VPP register block (301xx):
#
#   export_limit    → 0% blocks grid export, 100% allows full export
#   charge_enable   → 1/0 enables/disables battery charging
#   discharge_enable → 1/0 enables/disables battery discharge
#
# Mode presets:
#
#   Self-consumption:  export_limit=0,   charge=1, discharge=1
#   Charge battery:  export_limit=0, charge=1, discharge=0
#                    charge_power = max(0, pv_output - house_load - margin)
#
#   Use charge_power=MAX only when:
#     - Grid price is negative (charge from grid intentionally)
#     - SOC is critically low and time window is short
#   Otherwise size charge_power to available PV surplus to avoid
#   importing from grid just to charge the battery.
#
#   Export to grid:    export_limit=100, charge=0, discharge=0
#
# Notes:
#   - Load is always served first (hardware enforced, cannot override)
#   - charge_enable=0 blocks charging regardless of charge_power value
#   - Power values may be in W or dW (×10) depending on firmware version
#   - Some firmware requires writing a commit register after control writes
#
# Write via Modbus FC 0x06 (single) or 0x10 (multiple registers)

[jdungen]

Hi i have a VPP test running now on my 3PH MID 15KTL3-XH inverter with 30KW battery. see https://github.com/jdungen/bess-manager

2026-06-27 21:01:11 | INFO | core.bess.battery_system_manager:2328 - Period 84 (21:00): Intent=LOAD_SUPPORT, Action=-0.50 kWh (-2.00 kW), DischargeRate=13%
2026-06-27 21:01:11 | INFO | core.bess.battery_system_manager:2344 - HARDWARE: Setting discharge power rate to 13% for period 84
2026-06-27 21:01:11 | INFO | core.bess.ha_api_controller:1726 - Growatt VPP: power=-15%, allow_ac_charging=False, time=20 min (edge-triggered)
2026-06-27 21:01:12 | INFO | core.bess.power_monitor:190 - Phase loads: #1: 598W (10.4%), #2: 575W (10.0%), #3: 598W (10.4%)
2026-06-27 21:01:12 | INFO | core.bess.power_monitor:216 - Adjusting charging power from 100% to 0%

[johanzander]

Great process! Will have a look later but I'm almost out of my weekly Cluade Credits after massive work on 9.7.x ...

Could be a messy rebase to your fork if your work has diverged too much...