Hi all,
I’m running a 3-phase ESS system with a Victron MultiPlus-II GX and two additional MP2 5000 units. On the AC side I also have two Sungrow SG10RT string inverters that I’d like to integrate into the GX — read-only, just for monitoring.
The problem:
The GX does not detect the SG10RT, even though Modbus TCP is enabled (no encryption) on the Sungrow side, and the inverters are reachable on the network. I can confirm connectivity because my Loxone reads the Sungrow registers without issues.
With firmware 3.80~14 (Large), I can now configure custom Unit IDs and ports for PV inverter detection — great improvement! I’ve tried Unit ID 1 (Sungrow default) and 126 (SunSpec default), both on port 502. Neither works.
The root cause: The GX scans for the SunSpec identifier “SunS” at register 40000, which is the standard SunSpec base address. However, Sungrow inverters (especially the SG string inverter series accessed via WiNet-S/S2) do not expose SunSpec registers at 40000. They use a proprietary register layout starting at register 5000. While Sungrow is SunSpec-certified, this certification applies to their communication modules (WiNet-S, Logger1000, etc.), and the WiNet-S2 does not route all registers — including the SunSpec register block — through to the inverter.
This means the SG10RT is invisible to the GX regardless of the Unit ID setting.
Current workaround:
I’m using Node-RED to read the Sungrow Modbus registers and publish the data as a virtual PV inverter on the dbus. For a second SG10RT, I’ve installed a dedicated energy meter that the GX picks up as a PV inverter. Both workarounds function but add complexity and points of failure.
The feature request:
Since port and Unit ID are now configurable, could you also add a configurable SunSpec start register address to the PV inverter detection settings? This would allow the GX to scan for the “SunS” identifier at an address other than 40000.
Even better would be an option to define a custom Modbus register mapping (e.g. register address for AC power, AC energy, voltage, current) so that non-SunSpec inverters like Sungrow could be integrated natively — read-only monitoring would be sufficient.
This would benefit a large number of users who have existing Sungrow, Huawei, Growatt, or other inverters alongside their Victron system. These are among the most widely deployed inverters worldwide, and many users combine them with Victron storage systems.
Thank you for the continued improvements to PV inverter integration — the configurable Unit ID in the beta was already a great step forward.
System details:
- Victron MultiPlus-II GX + 2x MP2 5000 (3-phase)
- 2x Sungrow SG10RT with WiNet-S2 (latest firmware)
- Venus OS 3.80~14 (Large)
- Modbus TCP enabled on Sungrow, port 502, no encryption
- Sungrow reachable and readable via Loxone and Node-RED
