Connecting to SUN2000-4.6K-LB0 inverter

[deryckhans]

Hello all,

Today I had my old inverter, the SUN2000‑4.6KTL‑L1, replaced with the newer SUN2000‑4.6K‑LB0.

My old inverter successfully used the integration to connect to the built‑in AP at 192.168.200.1 on port 6607. Today I’m trying to configure the same on the new inverter, but so far without any luck. The only real change I’ve noticed is that the AP network’s IP range has been changed to 192.168.8.x. I haven’t tried connecting to the dongle yet, as that was advised against, but I will test that later.

Has anyone already been successful in connecting to this range on these inverters? I was told by the solar company that this model is “quite new”. If I can contribute to the integration by running some tests, I’d be happy to help.

Thanks,
H.

[deryckhans]

After some more testing, I can can confirm modbus is active on both built in AP (port 6607 on 192.168.8.1) and Donlge (port 502 on SDongleA-05).

But all attempts to connect to the inverter are failing.

[deryckhans]

Huawei provided me with the bellow information, apparently there are some important modbus changes introduced by the LB0 series

Why Modbus TCP worked on the old L1 but not on the new LB0

Modbus TCP is disabled by default on LB0 models

On the older L1 models, Modbus TCP was enabled automatically when the dongle was in “installer mode”. On LB0 models, Modbus TCP must be manually enabled in the installer menu.

If Modbus is not explicitly enabled, the inverter will listen on port 6607/502 but will not respond.

LB0 models require a Modbus access password
The inverter will not reply unless:

Modbus TCP is enabled
A Modbus access password is set
The client uses this password when connecting
Without the password, the inverter silently drops the request.

The dongle and the inverter do NOT share the same Modbus interface

Port 502 → Modbus TCP via the Smart Dongle
Port 6607 → Modbus TCP directly on the inverter AP/LAN
These are independent. If Modbus is disabled on one interface, it will not respond even if the other is enabled.

Steps to enable Modbus TCP on the SUN2000‑4.6K‑LB0

Step 1 — Connect to the inverter via FusionSolar app

Connect to Fusion Solar
Log in as Installer
Step 2 — Enable Modbus TCP

Menu path (LB0 models):

Device → Settings → Communication Configuration → Modbus TCP

Enable:

Modbus TCP
LAN access (if using dongle)
AP access (if using inverter Wi‑Fi)
Step 3 — Set the Modbus access password

You must create a password. This password is required for all Modbus TCP clients.

Step 4 — Reboot the inverter

LB0 models require a reboot for Modbus settings to take effect.

[wlcrs]

Hi Hans,

Can you verify if this answer is correct? Please upload screenshots where you perform step 3 in full (handy for adding to the docs later too).

Please ask Huawei how clients should provide that "password" to the inverter. This is a concept that does not exist in ModbusTCP, so they must be doing something custom here? Huawei has good technical documentation pdf's for these kind of things.

[deryckhans]

For the moment, I'm going back and forth with Huawei, as some of the steps do not align with what I'm seeing in the app. I suspect some of the answers to be (partly) generated by AI, so this might take some more time.

I will describe the steps/screenshots the moment I have the modbus replying.

[michaelvandorpe]

Caveat: my solar panels were installed just this week, I'm completely new to this, and while I've been trying different things to get past the configuration dialog of this HA integration, I have only be unsuccessful, with "unexpected errors" and nothing else.

The only thing that "works" is to test the connection as follows:
pi@raspberry:~ $ nc -zv 192.168.1.126 502
Connection to 192.168.1.126 502 port [tcp/*] succeeded!

When connecting to the device's own wifi AP, I have set the Communication Configuration in the FusionSolar app as follows (under Dongle parameter settings): "Start address for automatic address allocation = 1" and "Modbus TCP = Enable (unrestricted)"

Reading the above discussion, I am starting to think something changed recently? I also have an LB0 model.

And I'm wondering whether the "Modbus-TCP NMS" screen that I found under "Certificate management" is relevant here? The app does not allow me to take a screenshot, but it includes the following:

Root certificate > Select
Customer certificate > Select
Key file > Select
Key password - Enter the correct key password

Hitting "Select" brings up a standard file dialogue, allowing me to pick a file from the iPhone file system.

I have also tried specifying different slave numbers:
Exception on slave 0: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.826 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 1: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.529 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 2: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.534 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 3: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.634 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 4: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.824 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 5: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.529 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 6: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.534 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 7: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.634 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 8: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.824 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 9: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.529 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 10: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.534 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 11: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.635 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 12: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.824 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 13: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.529 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 14: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.534 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 15: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.634 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 16: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.824 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 17: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.529 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 18: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.534 seconds into read of unbounded read bytes without response from slave before it closed connection
Exception on slave 19: Modbus Error: [Connection] ModbusTcpClient 192.168.1.126:502: Connection unexpectedly closed 0.634 seconds into read of unbounded read bytes without response from slave before it closed connection

[deryckhans]

Allright, good to hear you have exactly the same behavior. This confirms Huawei's statements that unless activated, the modbus listens but drops all requests silently.

Pretty strange though that none of those changes are mentioned in their documentation. Or at least I didn't find it.

[michaelvandorpe]

No news? I haven't tried anything new myself in those two weeks... But of course, I would still really like to integrate this inverter into HA!

[deryckhans]

It has been a busy couple of weeks, I should be able to get arround to it it the next few days

[michaelvandorpe]

With the 2.0.0 update of the Huawei Solar integration, I was able to connect in seconds. Problem solved for me!

[deryckhans]

Hey Michael, just to be sure: do you have an SUN2000-xxx-LB0 model?

[diegobattistuzzi]

I have seen that this inverter is supported by "Network Connection via Modbus TCP with Modbus RS485 converter DR164 RS485 Wifi by PUSR", but there is no detail of this specifc connection. I don't know it whit battery and meter connected to RS485 it could work.

[steffenberthold]

I am not sure if my comment is helpful: I also have a SUN2000 inverter and a SDongle-05 and the HA Huawei Solar integration worked fine for a long time, but suddenly, 3days agon, all entities became "unavailable". reload, reconfigure was not successfull, I restarted HA and the Fritzbox several time and different order....not success. Tomorrow I try to check the SDongle....I tought it might have sth to do with the new HA Release 2026.4.3 because I updated in the last days.....

[deryckhans]

I received multiple mails from Huawei that they were going to change ip-addresses from their servers somewhere in April. Maybe your firewall is blocking the new addresses?

[ciori]

Hi @deryckhans and others, did you solve the issue or do youy have any update?

I am having the same problem, new recent installation of a SUN2000-5K-LB0 inverter, I have added a USB WiFi dongle to Home Assistant so that it is able to connect to the inverter's built-in WiFi AP. I have the same 192.168.8.x/24 range and I see only 6607 port is open.

These are the results of my tests:

For both slave 0 and 1

(ha web ui error)

(ha system logs)

...
huawei_solar.modbus_pdu.PermissionDeniedError: Modbus Exception 0x80 for function code 0x03
...
huawei_solar.exceptions.ReadException: Failed to read registers model_name: received PermissionDeniedError
...

For slave 2 and above

(ha web ui error)

(ha system logs)

Could not connect to one of the slave devices on 192.168.8.1:6607

From this project's guide I guess I should use slave number 0, am I right?

Then for the modbus thing, I tried to follow the guides to enable modbus tcp, but what i get in the fusion solar app (after logging is as an installer) is different from those tutorials, different menu names and I was not able to find a clear "enable modbus tcp" section.

[ciori]

My doubt is: have huawei completely locked up modbus tcp on newer devices/firmware?

[deryckhans]

Hello ciori,

Sorry about the late reply, the last time I checked this, I was seeing a lot of different / missing options in the app in regards to what I was instructed by the Huawei support team. I have a lot of (unrelated) stuff on my head for the moment, so I will not be able to investigate this further immediatly, but was I get around to it, I will let you know.

In the meanwhile, don't hesitate to keep me posted on your progress

[steffenberthold]

What I can say is that my Inverter has firmware V174, my dongle has V120 and I use the integration v2.1.0. Fingers crossed I can say all works fine.Von meinem/meiner Galaxy gesendet -------- Ursprüngliche Nachricht --------Von: ciori ***@***.***> Datum: 24.05.26 21:30 (GMT+01:00) An: wlcrs/huawei_solar ***@***.***> Cc: steffenberthold ***@***.***>, Comment ***@***.***> Betreff: Re: [wlcrs/huawei_solar] Connecting to SUN2000-4.6K-LB0 inverter (Discussion #1289) My doubt is: have huawei completely locked up modbus tcp on newer devices/firmware? —Reply to this email directly, view it on GitHub, or unsubscribe.Triage notifications on the go with GitHub Mobile for iOS or Android. You are receiving this because you commented.Message ID: ***@***.***>

[deryckhans]

Can you confirm you also have the SUN2000-4.6K-LB0?

[steffenberthold]

I have SUN2000-8KTL-M1 Mit freundlichen Grüßen / best regards Steffen Berthold Am Mittwoch, 27. Mai 2026 um 11:43:15 MESZ hat deryckhans ***@***.***> Folgendes geschrieben: Can you confirm you also have the SUN2000-4.6K-LB0? — Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS and Android. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[deryckhans]

Allright, I have been able to invetigate this further. Huawei support have now confirmed modbus is no longer being exposed via the built-in wifi on the LB0 models.

1. LB0 models do NOT expose Modbus TCP on Wi‑Fi
   According to Huawei’s official SUN2000‑L0/LB0 communication guide:

Modbus TCP is NOT available on the inverter’s internal Wi‑Fi AP.
Modbus TCP is only available through the Smart Dongle (SDongleA‑05 or SDongleA‑03).
The inverter’s Wi‑Fi AP is now monitoring‑only, not a Modbus interface.
This is why your previous method (connecting directly to the inverter Wi‑Fi) no longer works.

Modbus connection should only be done via the Dongle, but again they are asking me to configure settings that I don't see in my device configuration. Feel free to give it a try yourself.

2. Enable Modbus TCP on the Smart Dongle (official procedure)

Modbus to be enabled on the dongle, not on the inverter.

Steps (from FusionSolar App → Installer mode):
Go to Device Management
Select Smart Dongle
Open Settings
Enable:
[Modbus TCP] = ON
[Third‑party Monitoring] = ON
Confirm that the dongle has a valid LAN IP address
Reboot the dongle (short press 3 seconds)
Important: On LB0 models, enabling Modbus on the inverter itself is not sufficient. The dongle is the Modbus server.

3. Use the correct Modbus TCP port

Port 6607 → Modbus TCP via Smart Dongle
Port 502 → Not supported on LB0 models
If you try port 502, communication will fail.

4. Ensure the dongle is in “Normal Mode” (not in AP mode)
   Modbus TCP only works when the dongle is connected to the LAN.

Check LED status:

Green steady → Normal network mode
Blue → AP mode (Modbus disabled)
If blue → press button 1 second to exit AP mode.

5. Assign a fixed IP address to the dongle
   We recommend a static IP for Modbus polling stability.

You can set this:

In your router (DHCP reservation)
Or in the dongle network settings (Installer mode)
6. Verify that Modbus is not blocked by the router
following ports to be open:

6607 TCP (Modbus TCP)
10000–10005 TCP (FusionSolar communication)
If your router/firewall blocks port 6607, Modbus will drop.

7. Check the maximum number of Modbus connections
   Official limit:

Max 5 Modbus TCP clients simultaneously
If more clients connect (Home Assistant, EMS, monitoring tools), the dongle will drop connections.

[deryckhans]

SOLVED!

Not sure what exactly happened, but I can only assume an update was executed that recognized the LB0. As mentionned above, Huawei does not expose the Inverters onboard wifi any more, so you have to connect to the dongle. In my case, it worked with port 502 and auto detect client id.