Installation · Growatt

Install GridZeno on Growatt WIT 29.9-50K-XHU.

WIT 29.9-50K-XHU is a wide three-phase hybrid inverter that hangs on the wall. On the underside is COM1, with nine RJ45 ports under a waterproof cover. The dongle goes in the RS485-1 port, where pins 7 and 8 are Growatt's connection for an external controller (EMS/VPP). The inverter needs no settings.

Applies to: WIT 29.9K, 30K, 36K, 40K and 50K-XHU
Connection: Network cable with RJ45 plug
Time: About 25 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 29.9-50K-XHU

How the dongle recognises it: The type code 5601. The Home Assistant integration Growatt_ModbusTCP calls 5601 a WIT 29.9-50K-XHU after a register scan; Growatt's VPP protocol V2.01 calls it a WIT 100KTL3-H. Both are controlled as WIT above 15 kW.

GridZeno Dongle for Growatt WIT 29.9-50K-XHU

What you need

GridZeno Dongle: The device ID is on the label, e.g. GZ-A1B2C3.
Cable: Cat5e cable with a thickness of 5.5 to 7 mm, so it fits the holes in the cable gland.
RJ45 plug and crimping tool: For the inverter end, which is crimped after the cable has been passed through the cover.
Screwdriver: For the four screws in the COM1 cover.
USB power: A 5 V USB charger and a cable with USB-C.

The port

On the underside, between the MPPT inputs and the USB port. COM1 has nine RJ45 ports under a waterproof cover with two cable glands: BMS1, RS485-1 and RS485-2 at the top, BMS2, PARA-IN and PARA-OUT in the middle, BMS3, METER and DI at the bottom. RS485-2 has the same pins.

Port: RS485-1 (in COM1)

The RS485-1 port, with Growatt's pin numbering. RS485_3 on pins 7 and 8 is for EMS/VPP. 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 cable gland in the COM1 cover 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

Communication address: 1, as from the factory. It's only changed with Growatt's ShineBus, by an installer.
Modbus: Modbus RTU at 9600 baud, 8N1. 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 COM1 cover
Turn off the AC breaker, set the DC switch to OFF, and disconnect the battery. Wait 5 minutes. Undo the four screws in the waterproof cover over COM1, and remove the cover.
2
Pass the cable through the cover's cable gland
Loosen the cable gland, take a plug out of the five-hole sealing ring, and press the cable into the hole from the opening at the side. Pass the cable through the cover. Leave the plugs in the holes you don't use.
3
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.
4
Plug the connector into RS485-1
Press the plug into the port marked RS485-1, at the top in the middle, until it clicks. RS485-2 next to it has the same pins.
5
Screw the COM1 cover back on
Put the cover on, put in the four screws, and tighten the cable gland so the sealing ring sits correctly.
6
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.
7
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.
8
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.
9
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 RS485-1 or RS485-2. BMS1 to BMS3 are the batteries' connections and METER the energy meter's.

Pins 1, 4 and 5 in RS485-1 are Growatt's own connection to meter 2 and ShineBus. They must not be used by the dongle.

What GridZeno can control on Growatt WIT 29.9-50K-XHU, and how, is on the page about Growatt WIT 29.9-50K-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 29.9-50K-XHU User Manual (EN, 2025-04), Section 3.1, Overview, 6.5.1, COM1 Connection, with figures 6.17-6.20 and table 6.5, and 7.1.1, Set the Communication Address.