SunSpec needed?

[treyus30]

Hi, I have inherited 2 solar edge inverters with LG batteries. It's been a trip getting them figured out but at least I have each inverter meter + an export meter configured now. Home assistant reports what I'd expect, though terminology is wacked out. Right now the most annoying thing is no battery access, so it looks like solar is on at night, and I have no idea how much energy is left. Also it seems to not doing a DC-coupled battery charge (??), today it presented as AC from one inverter into negative AC into the other.

I have read I am apparently one of the "unlucky" that dont have power or battery control over modbus. However, I just want to make sure there are no workarounds. I have both wired into a physical ethernet switch which runs back to a router.

I have the HBI (home backup interface) which is on the RS485-2 bus so I think it needs SolarEdge protocol, but the other option is SunSpec, which documentation says is for non-SolarEdge (which would be HA). Is there anything to try there?

Is there any sense in trying to make my own RS485 to ethernet (TCP) to bypass these arbitrary restrictions? (The statuses are visible on the SetApp, so clearly they are accessible on the bus itself). Will this add-on recognize the protocols the same way?

[WillCodeForCats]

I don't know exactly what the SolarEdge Leader/Follower protocol is. It could be based on a standard, or proprietary, or a mix of some standard with proprietary stuff added on. I would lean towards proprietary since, for example, we know follower inverters are reporting optimizer status to the leader over the bus but that data isn't available over modbus (as far as anyone has been able to find).

I would think the most straightforward way is to convince SolarEdge to enable batteries over the modbus interface. I know some people have reported they were able to get that done, but personally I don't have batteries so I don't have any direct experience.

[treyus30]

'I would think the most straightforward way is to convince SolarEdge to enable batteries over the modbus interface.'

I'm trying to avoid direct contact with them right now for two reasons: 1. They want $100 to transfer the system to my name, so they likely wouldn't entertain helping me until I go through that process. 2. One of the two batteries is having internal BMS issues and requires an official installer to come look at it. That installer should know a lot about these inverters and I hope to pick their brain when they're here - maybe they can ask solar edge and have more negotiating power than I would

[WillCodeForCats]

I have the HBI (home backup interface) which is on the RS485-2 bus so I think it needs SolarEdge protocol, but the other option is SunSpec, which documentation says is for non-SolarEdge (which would be HA). Is there anything to try there?

I totally skipped over this in my other reply; I was thinking about tapping the SolarEdge protocol bus and intercepting what the Follower devices send to the Leader device.

Yes, in theory the SunSpec port option might be the same thing as the Modbus/TCP interface as a serial port interface. I even bought a USB to RS485 serial adapter to try adding a serial port connect option to the integration, but I never actually tried it. If it is it should work the same.

[treyus30]

So do you think something like this is worth a try, and it would just plug right in?
https://www.amazon.com/RS485-High-Speed-High-Stability-Up-gradable-Communicate/dp/B07RQK56TM
or
https://www.amazon.com/waveshare-Independent-Operation-Rail-Mount-Industrial/dp/B0CQYGDMDK
(greatest thing about Amazon is the free returns!)

[WillCodeForCats]

You can try and report back, but I don't know.

[treyus30]

@WillCodeForCats So I got one of the 4-ch Waveshares and got it connected to where I can get some readable hex data in a serial terminal, but only at 9600 baud which I feel is weird when the default is 115200. This is specifying Modbus TCP protocol, everything else gives 0s.

If I plug this into your integration, I get hit with a couple different errors that I'm hoping you can interpret better than I:

To me it seems to be saying its expecting a speed 3x faster, given the registers, but I'm not sure what 40000 references.

Here's some sample data:

[WillCodeForCats]

The integration requires the same responses a SolarEdge inverter would return, and those errors mean it's not doing that.

[ChristophCaina]

Hi there,
coming to this discussion a bit late — is this still an open issue for you?

Looking at your setup and the errors, I think the root cause is the baud rate mismatch. You mentioned you can only get readable data at 9600 baud, but SolarEdge RS485 runs at 115200 baud by default. At the wrong baud rate, the Waveshare adapter will receive garbled or truncated data — which explains both errors:

• Registers received != requested: 23 != 69 at 40000 — the SunSpec header registers are being read incorrectly due to corrupt data
• ID 1 is not a SunSpec inverter — because the SunSpec identifier (0x5375 = Su) at register 40000/40001 can't be read correctly

SolarEdge does implement SunSpec and should respond with the correct Su identifier — but only if the physical layer (baud rate, parity, stop bits) matches exactly. Try setting the Waveshare to 115200 baud, 8N1 and see if that changes things.

If you do get SunSpec working over RS485/TCP, you might then run into a second issue that's less obvious: SunSpec itself is not as uniform as it sounds. The standard actually allows two different data formats:

• Integer model — values stored as int16 with a separate scale factor register (e.g. 2071 × 10⁻² = 20.71 W). This is what SolarEdge uses.
• Float model — values stored directly as float32 (IEEE 754). This is what some other devices (e.g. Bosch Energy Manager) expect.

Both are fully valid according to the SunSpec specification — but a device using one format cannot directly talk to a client expecting the other. So even if two devices are both "SunSpec certified", they may still be incompatible with each other.

If you want to connect multiple devices that expect different formats simultaneously, a Modbus proxy with transparent format conversion can bridge the gap — without touching the inverter or the clients.

Hope this helps — even if it's a bit late to the party!