Installation · Growatt

Install GridZeno on Growatt WIT 50-125K-XHU.

WIT 50-125K-XHU is Growatt's large hybrid inverter that stands on the floor. The communication is on the right side in a waterproof COM connector with six RJ45 ports. The dongle goes in one of the two RS485 ports, where pins 7 and 8 are Growatt's connection for an external controller (EMS).

Needs an electrician: the inverter has to be opened

The side cover on the right side has to come off, and behind it are also the connections for grid, load, PV and battery. It should be done by a qualified person, e.g. an authorised installer.

Applies to: WIT 50K, 63K, 75K, 85K, 99.9K, 100K and 125K-XHU
Connection: Network cable with RJ45 plug
Time: About 30 minutes

Controlled like the Growatt WIT: charging and holding with the inverter's operating mode, selling with Growatt's VPP protocol. The dongle always sets the inverter's own mode back afterwards. What GridZeno can do on Growatt WIT 50-125K-XHU

How the dongle recognises it: No type code of its own in any table. The dongle sees 5603 and a rated power in 30016 above 15 kW and treats it as a WIT above 15 kW.

GridZeno Dongle for Growatt WIT 50-125K-XHU

What you need

GridZeno Dongle: The device ID is on the label, e.g. GZ-A1B2C3.
Cable: Cat5e cable, long enough to reach from the inverter to the dongle.
RJ45 plug and crimping tool: For the inverter end, which is crimped after the cable has been passed through the COM connector's parts.
Screwdriver: For the side cover on the right side.
USB power: A 5 V USB charger and a cable with USB-C.

The port

On the right side behind the side cover, below the USB port and next to the LAN1 and LAN2 cable glands. The COM connector has six RJ45 ports: 2, 4 and 6 at the top, 1, 3 and 5 at the bottom. Ports 2 and 3 are RS485, 1 is BMS, 4 is DI and 5 and 6 are for parallel operation.

Port: RS485 (port 2 or 3 in the COM connector)

The RS485 port, with Growatt's pin numbering. RS485_3 on pins 7 and 8 is for SEM/EMS. The plug shown with the contacts facing you and the locking tab at the back: pin 1 is furthest to the left.

Pin 8 A, RS485_3A
Pin 7 B, RS485_3B
Pin 2 GND, GND.S

The cable

A network cable where the inverter end is crimped with only three wires: the dongle's A on pin 8, B on pin 7 and GND on pin 2. The rest of the positions in the plug are empty. An ordinary straight cable doesn't work here, because the GridZeno dongle has A and B on pins 4 and 5, and Growatt on pins 8 and 7. The cable has to go through the COM connector's seal and housing before the plug goes on at the inverter end, so that end is crimped on site with an RJ45 crimping tool.

From the dongle to the inverter
Dongle end	Inverter end
Dongle pin 4, blue (A)	Growatt pin 8, RS485A
Dongle pin 5, white/blue (B)	Growatt pin 7, RS485B
Dongle pin 3, white/green (GND)	Growatt pin 2, GND
The other wires	Cut off and insulated

Settings

On the inverter

Modbus: Modbus RTU at 9600 baud, 8N1 and address 1. That's what the dongle uses from the factory, so there's nothing to set.

In GridZeno's Welcome

The inverter is chosen in GridZeno: in Welcome the first time, and later under System, Change inverter. The dongle fetches its setup from there.

Manufacturer and model: Growatt, WIT over 15 kW
Connection: By cable (RS485)
RS485 settings: Keep the default: 9600 baud, 8N1, address 1.

Step by step

Each step has a small drawing that shows what to do.

1
Switch off the inverter, and remove the side cover
Turn off the AC breaker, set PV SWITCH 1 and 2 to OFF, and turn off the battery's breaker. Wait 5 minutes. Unscrew the side cover on the right side.
2
Remove the cap from the COM connector
The COM connector is below the USB port, next to LAN1 and LAN2. Remove the waterproof cap, and pull out the connector housing.
3
Pass the cable through the connector's parts
Pass the cable through the sealing insert, the clamp and the connector housing, in that order, before the plug is crimped on.
4
Terminate the cable with an RJ45 plug
Strip 15 mm, and crimp the RJ45 plug on with blue (A) on pin 8, white/blue (B) on pin 7 and white/green (GND) on pin 2. The other wires are cut off and insulated.
5
Plug the connector into the RS485 port
Press the plug into port 2 at the top left until it clicks. Port 3 at the bottom in the middle has the same pins.
6
Put the COM connector back in
Press the COM connector in until it clicks, and tighten it so the seal sits correctly. Screw the side cover back on.
7
Plug the RJ45 end into the dongle
The cable's other end goes into the dongle's RS485 port. Place the dongle somewhere dry and close to the inverter, so the cable doesn't hang from the plug.
8
Connect power to the dongle
Plug the USB-C cable into the dongle and the charger into a socket. The dongle starts by itself. It gets power from the charger, not from the inverter.
9
Connect the dongle to the network
Over Wi-Fi: the first time, the dongle creates its own Wi-Fi, GridZeno-Setup- followed by the last characters of the device ID. Connect your phone to it, choose your own network, enter the password, and press Save and connect. When it says Connection OK, press Go to GridZeno. Over cable (LAN): plug a network cable from the router into the dongle's network port.
10
Log in, and choose your inverter
Log in to GridZeno. Welcome pairs the dongle with its device ID. Then choose your inverter, Growatt WIT, and the connection By cable (RS485). Press Save inverter, and the dongle fetches its setup and reads the inverter.

The dongle's own setup is described with screenshots in The user guide, and the pairing in Getting started.

Take care

Use port 2 or 3. Port 1 is the battery's connection, and the energy meter is in the 8-pin terminal next to the ports.

Pins 1, 4 and 5 in the RS485 port are RS485_1. They must not be used by the dongle.

What GridZeno can control on Growatt WIT 50-125K-XHU, and how, is on the page about Growatt WIT 50-125K-XHU. If you're stuck, write to us with the model name.

Source

Ports, pins and menus are from the manufacturer's own manual: Growatt WIT 50-125K-XHU User Manual (EN, 2026-06), Section 3.1, Overview, 6.3, Communication Connection, with figures 6.12-6.14 and table 6.5.