Bug: Serial number (SN) field limited to 10 characters — too short for some EV Charger models

[Sturmi77]

Bug Description

The config_flow.py has a hardcoded maximum length of 10 characters for the serial number (SN) field in both CONFIG_SCHEMA and OPTION_SCHEMA:

vol.Required(CONF_SN): vol.All(
    str, vol.Length(max=10, msg="invalid_sn_length")
),

This prevents users from entering serial numbers longer than 10 characters. The SolaX EV Charger (X3-EVC series) can have serial numbers of 14 characters (e.g. C32203XXXXXXXX), making it impossible to set up the integration via the UI.

Impact

• Integration cannot be configured at all for affected devices
• Workaround requires manually patching config_flow.py after every HACS update

Steps to Reproduce

1. Install integration via HACS
2. Go to Settings → Devices & Services → Add Integration → SolaX HTTP
3. Enter a serial number longer than 10 characters
4. UI rejects input with invalid_sn_length error

Expected Behavior

The SN field should accept serial numbers of at least 20 characters to accommodate all current and future SolaX EV Charger models.

Suggested Fix

In config_flow.py, change both occurrences of max=10 to max=20 (or remove the length restriction entirely):

# CONFIG_SCHEMA
vol.Required(CONF_SN): vol.All(
    str, vol.Length(max=20, msg="invalid_sn_length")
),

# OPTION_SCHEMA
vol.Required(CONF_SN): vol.All(str, vol.Length(max=20)),

Environment

• Integration version: v1.4.1
• Home Assistant: 2026.03.x
• EV Charger model: SolaX X3-EVC (serial number prefix C322)

[Sturmi77]

Additional findings: X3-EVC-22K(PXH) not supported via local HTTP API

After further investigation, the root cause of the NoneType error for this specific device goes beyond the SN length limit.

Device: SolaX X3-EVC-22K(PXH)

The (PXH) suffix indicates a newer generation EV Charger with its own integrated WiFi module. This model behaves differently from older EVC models:

Symptoms:

1. Device responds on port 80 (browser shows a credential dialog with username + password)
2. curl -X POST http://<ip> -d 'optType=ReadRealTimeData&pwd=<SN_or_RegNo>' returns message failed (not Status failed)
3. Both the serial number (C32203xxxxxxxx, 14 chars) and the Registration No. fail as password
4. The plugin_factory.py receives None from _read_device_info() because the API response contains "failed"

Root cause:
The X3-EVC-22K(PXH) uses a different authentication mechanism on its local HTTP API — it requires a proper HTTP login (username + password via browser dialog), unlike older EVC models that accept the Registration No. as pwd= parameter in the POST body.

The optType=ReadRealTimeData&pwd=... endpoint either:

• Is not supported on this firmware generation, or
• Requires the WiFi module's Registration No. in a different format

Workaround:
Use the SolaX Cloud API instead (https://www.solaxcloud.com/proxyApp/proxy/api/getRealtimeInfo.do?tokenId=...&sn=...) via a REST sensor in configuration.yaml. Data updates every 5 minutes.

Summary of two issues found

Issue	Affected devices	Fix needed
SN field max=10 too short	All devices with SN > 10 chars (e.g. C322xx = 14 chars)	Increase to max=20
Local HTTP API incompatible	X3-EVC-22K(PXH) and likely other newer (PXH) models	Needs investigation of new auth mechanism

Would be great if the README could document which EVC models/generations are supported via local HTTP API and which require Cloud API as fallback.

[PatrikTrestik]

Have you tested Modbus TCP on this new model?

Cloud API is not fallback, it is only for reading without option to automate charger.
For cloud API you have to be connected. Most of the users are intentionally disconnecting from SolaX cloud so it is no option.

If Modbus TCP works, I suggest to use SolaX modbus integration.

[Sturmi77]

I will give it another try. Modbus Integration works for my inverter since years but I never made it work for the EV Charger. I would absolutely prefer the local version without doubt.

[PatrikTrestik]

I will give it another try. Modbus Integration works for my inverter since years but I never made it work for the EV Charger. I would absolutely prefer the local version without doubt.

Modbus TCP is new on EVC. I do not know which FW version added it, but it is one of latests. If you have one of older FW upgrade first.