[Bug]: SoC reports 16% when Solax Cloud reports 10%

[RGx01]

Describe the bug

Upgraded to 2026.05.5 today and observed some odd SoC behaviour after a discharge (SoC creeping up by 6%). On the final discharge of the day it stopped at 16% and couldn't figure out why it wouldn't go to 10%. Logged into solax cloud and it was reporting SoC of 10%, looking at the cloud SoC where I saw odd SoC behaviour of SoC creeping up, the cloud trace has non of that. Rolled back to 2026.05.03 and SoC dropped back to 10%.

Integration Version

2026.05.5

Homeassistant core version

2026.5.4

Inverter brand

X1-Hybrid-5.0kW by SolaX Power Firmware: DSP 1.58 ARM 1.53 Hardware: Gen4

Plugin used

plugin_solax.py

Serial prefix

H4502A

Inverter firmware versions

DSP 1.58 ARM 1.53

Connection Method

Solax pocket wifi 3

Dongle firmware

1.006.01

Detailed Error Log

No response

Additional context

[Pengo429]

My SOC just stays at 0%. Same inverter, same firmware. On this integration version and the previous.

[TCWORLD]

@RGx01 what is the value of "Modbus Protocol Version" on the latest release.

Which battery capacity sensor are you using? "Local Battery SoC" is not a name I recognise.

What do you mean by "SoC creeping up" - could you show the data from the cloud platform and mark on the screenshot which bit you are indicating.

[TCWORLD]

@Pengo429 Same question to you. What is the serial prefix (6 digits), firmware version and modbus protocol version, and what battery capacity sensor are you looking at.

[Pengo429]

sensor.solax_battery_capacity 2026.05.5 this morning, 2026.05.4 last night. Just reverted back to 2026.05.3:

[TCWORLD]

@Pengo429 What is the serial prefix (first 6 digits), firmware version and modbus protocol version?

[Pengo429]

Modbus protocol version: 100
Serial prefix: H4502A
Firmware ver????: DSP 1.58 ARM 1.53

[TCWORLD]

Interesting.

No idea why the inverter is not respecting the latest protocol docs when it's reporting the modern protocol version (100).

Could you check whether "SolaX PV Power Total" was reporting the correct value when you had 2026.05.5 installed?

[Pengo429]

SolaX PV Power Total was correct with 2026.05.5
BTW: I had to enable modbus protocol version to display it.

[TCWORLD]

Thanks for confirming. Very glad the total PV sensor was still working!

There's been a lot of problems caused by SolaX changing the Modbus registers between different firmware/protocol revisions (primarily issues with GEN6 inverters). I thought we'd managed to iron out the problems, but it seems clearly there are still some discrepancies.

This should be fixed by #2099. If you want to test the changes, make sure 2026.05.5 is installed, then overwrite plugin_solax.py with the file in the linked PR and restart home assistant.

[RGx01]

Protocol entity was disabled in 2026.05.5, just enabled it on 2025.05.3 and it reports 100. Sorry about the capacity entity, its sensor.solax_inverter_solax_battery_capacity. I only recently started using this great integration after local API access was disabled on my dongle. I had lots of automations so remapped the modbus entities to my old entity values. just not untangled the templates/automations/dashboards yet.

[RGx01]

The cloud was actually reporting about 11% lower at 21:15 after the discharge where you see SoC creeping up.

[jefft4]

My SOC just stays at 0%. Same inverter, same firmware. On this integration version and the previous.

Me also - reported SoC went to zero after an update and stayed there. I've raised #2102 with logs. At a guess, it's reading the wrong register. I'll have a look at the code if I get time later.