Adding VPP registers to GEN4 Growatt inverters to control battery first / grid first

[brad5505]

Since the recent solax modbus update,I have been using VPP registers for my GEN3 Growatt inverter to control battery first / grid first. This all works well.
Background information at
#1631
and
#1759

I didn’t include VPP registers for GEN4 inverters as I could not test it. I have now updated the plugin_growatt.py file to include the registers for GEN4 inverters and would welcome anyone with a GEN4 inverter to test this before I submit an new PR.

Attached is the plugin_growatt.py file. Any feedback would be great.

plugin_growatt.py

[bartbutenaers]

Hi @brad5505

First of all thanks for all your hard work to provide cool stuff to people like me!!

Hardware

To give you some hardware context, this is my setup:

• Growatt 3PH MOD 10KTL3-XH BE(BP): Hybrid Inverter
• Growatt ShineWiLan-X2: Datalogger
• Growatt APX 5.0P-B1: battery module 5 kWh => 3 modules * 5 kWh = 15 kWh
• Growatt APX 98034-P2: BMS

Scripts

I created - based on your feedback - a test script to start charging my battery for 5 minutes at 50% load:

sequence:
  - action: number.set_value
    target:
      entity_id: number.growattmodbus_inverter_vpp_time
    data:
      value: 5
  - action: number.set_value
    target:
      entity_id: number.growattmodbus_inverter_vpp_power
    data:
      value: 50
  - action: select.select_option
    target:
      entity_id: select.growattmodbus_inverter_vpp_remote_control
    data:
      option: Enabled
  - delay:
      seconds: 1
  - action: select.select_option
    target:
      entity_id: select.growattmodbus_inverter_vpp_status
    data:
      option: Enabled
alias: Start loading battery
description: ""

I created also a test script to stop charging my battery:

sequence:
  - action: number.set_value
    target:
      entity_id: number.growattmodbus_inverter_vpp_time
    data:
      value: 0
  - action: number.set_value
    target:
      entity_id: number.growattmodbus_inverter_vpp_power
    data:
      value: 0
  - action: select.select_option
    target:
      entity_id: select.growattmodbus_inverter_vpp_remote_control
    data:
      option: Disabled
  - delay:
      seconds: 1
  - action: select.select_option
    target:
      entity_id: select.growattmodbus_inverter_vpp_status
    data:
      option: Disabled
alias: Start loading battery
description: ""

First test

When I started my first test, I suddenly got large peaks. But it was apparently my wife, who had decided that it was a the perfect timing to activate both the oven and the iron 😖. So my experiment wasn't really conducted under laboratory conditions...

Second test

The second test was much better 👍👍

• I first ran the start script, and it started charging the battery. And 5 minutes later it automatically stopped charging.
• Then I ran the start script, and a minute afterwards I ran the stop script. And it nicely stopped loading immediately.

So to me your Gen4 patch seems to be working fine 😍

Questions

1. As you can see in my chart above, there is almost always charging power. I.e. the charging power is never zero, although the battery (I thought...) is not charging . Very weird, to me at least... So this is NOT related to your code, but perhaps any body reading this can illimunate me about this...

2. The charging power is 3kW, and it is not clear to me why. When looking at the datasheet of my converter, the maximum charge power of my inverter is 10kW:

   

   The 3kW is not 50% of this 10kW...

   So I thought that perhaps the battery itself has a limiting charging factor. When look at the datasheet of my battery, the maximum power is 7,5 kW:

   

   So again the 3kW is not 50% of 7,5kW. Although this datasheet mentions output power only, which is perhaps not related to charging.

   Do you (or anybody else reading this), have any idea why my charge power is 3kW?

3. I had setup previously a charge limit of 2,6kW:

   

   I had expected that this limit would be taken into account also for VPP, but that doesn't seem to be the case (because 3kW > 2.6kW). Is then my theory correct that VPP overrules every other setting, because it is (among others) being used when you sign a contract with an aggregator company. And you let them use your battery to stabilize the grid, so you are not allowed to limit them in any way using other settings?

4. Do you know if it is only possible to load X minutes, or e.g. until the SOC is Y% ?

Thanks and enjoy your sunday!
Bart

[scruysberghs]

Hi guys, I have been playing around with the VPP registers for a couple of months. Nice to see these added to Solax modbus Growatt plugin.

With regards to the conversion from actual power to the VPP power percentage you have to use the value in register 30026, sadly this register isn't yet available in the solax growatt plugin. Would be nice if someone could add it.
So if this gives you 6000W sending 50%/-50% to register 30409 will send 3000W/-3000W to/from the battery

With registers 30100 and 30407-8-9 now available in the plugin you have all the registers you need to control your battery 24/7
If 30026 is added I can drop my custom modbus yaml stuff...

[brad5505]

Hi @scruysberghs

My percentage power values equate well to my SPH 5kW inverter. The percentage values are proportional to 5000w ( eg -20% gives me a battery discharge of 1000w). I did read my 3026 register and it gave me 6000w. So im my case, if I used the 30026 value, my ratios would be wrong.

Unsure why you need to use the 30026 value. This is a read only register, and the value probably does not change.

Below is the code I added to my plugin_growatt.py

GrowattModbusSensorEntityDescription(
    name="Rated battery charging",
    key="rated_battery_charging",
    native_unit_of_measurement=UnitOfPower.WATT,
    device_class=SensorDeviceClass.POWER,
    state_class=SensorStateClass.MEASUREMENT,
    register=30026,
    register_type=REG_HOLDING,
    unit=REGISTER_U32,
    scale=0.1,
    rounding=1,
    allowedtypes=GEN3 | GEN4,
    entity_category=EntityCategory.DIAGNOSTIC,
    entity_registry_enabled_default=True,
    icon="mdi:battery-sync",
), 

[scruysberghs]

haven't tried it with a SPH but for MID and MOD inverters you do have to use the % of register 30026 to get a linear and correct translation from power to %. If you use rated power of the inverter itself it will be off (so I have to use 6000W instead of the 50000W in your example)
Have you tried calibrating 10 20 30 40 50 60 70 80 90 100% to see what happens with the battery power? Is it linear?

[brad5505]

I only have a SPH inverter, so it maybe different with other inverters. For my SPH inverter I have not done a full calibration. I have only used -20%, -80%, +20 and +80%. For these settings, the results (discharge and charge rates) were as expected.

[brad5505]

Thanks for testing the VPP settings on your GEN4 inverter. Glad it all seems to work. I will now create a PR to have this incorporated into the solax-modbus integration.

Unsure why your battery charging power is limited to 3000w. Maybe try setting the VPP inverter power to 100, to see if the 3000w is a hard limit or it goes up to 6000w.

Also, unsure why you see fairly constant low charging. Does your system include Solar panels. Do you see the same thing at night? Could it be some type of offset for self consumption.

[wills106]

Just released these changes in 2026.01.2 thanks

[bartbutenaers]

Thanks @wills106 and @brad5505 !!

[brad5505]

Thanks @wills106 for publishing and thanks @bartbutenaers for the testing

[bartbutenaers]

Thanks. Yes indeed I have solar panels. Will need to analyze the charts and settings to get familiar with my setup and how it behaves.

I have used your VPP mechanism for the first time to load my battery during the night hours (at a bit cheaper night tariff), using two automations

• The first automation is triggered at 01:00 and starts charging via VPP (with VPP time 0 and VPP power 50%).
• The second automation is triggered at 07:00 and stops charging via VPP (with VPP time 0 and VPP power 0%).

Until now I did that every night which was very accurate. But now it looks different from what I had expected:

1. It starts loading correctly at 01:00 but at a charging power around 2.4kW. No idea why it is using these power values.
2. At 05:30 the charge power suddenly drops to around 1,5kW. Again no idea why.
3. My second automation did not run (due to a stupid error in my yaml) but then you see that the charging power gradually drops until the battery is 100% full. I had expected it to go at full power until the battery was completely full, but that isn't the case.

I assume this has nothing related to your PR. But just mentioning it here, in case anybody else has similar experiences...
Will need to digg into my settings to analyze this.

[ridax67]

Has anyone had any success with VPP AC charging at maximum speed? My setup normally AC charge at 10kW max, but in VPP mode I can only get it to charge at around 4-5kW. The VPP power register clearly calculates with 10kW because it is linear up to around 40-50% and then doesn't increase regardless of power values.

[brad5505]

Having solar panels may explain the fairly constant low charging during the day if it was overcast.

What VPP time did you use? You had 0 in your post.
The first automation is triggered at 01:00 and starts charging via VPP (with VPP time 0 and VPP power 50%).
The second automation is triggered at 07:00 and stops charging via VPP (with VPP time 0 and VPP power 0%).

Battery charge rates for me reduce between about 97% and 100% SOC. This would explain some of the reduction in charge rates you observed. If you graph SOC along with battery charge power, you maybe able to see a pattern to determine at what SOC the charge rate changes.

[bartbutenaers]

Yes indeed my first automation has vpp time 0, because the docs tell that this means infinite. I thought that would be the best choice, since I have a second automation to explicit stop loading.

Yes you are correct about the constant loading from my solar panels. How stupid of me. Thanks for the insights!!!

What do you mean with "Battery charge rates for me reduce between about 97% and 100% SOC"?

[brad5505]

Yes indeed my first automation has vpp time 0, because the docs tell that this means infinite. I thought that would be the best choice, since I have a second automation to explicit stop loading.

I normally put in a VPP time value as a safety feature, so if Home Assistant crashes for some reason or my wifi router drops out , the inverter will still swith the VPP settings off.

[brad5505]

Safety Feature near 100% SOC (Tapering): When a battery is near full capacity, it becomes harder for the lithium ions to be absorbed into the anode. If high-speed charging continues, the excess energy turns into heat, which can cause internal damage, reduce life, or lead to thermal runaway. The BMS reduces the current to prevent this.