Installation · Growatt

Install GridZeno on Growatt WIT 50-100K.

WIT 50-100K is Growatt's large three-phase inverter, which stands on the floor or hangs on the wall. The communication is in a panel on the right side, behind a cover. The dongle is connected with two wires in the 16-pin connector COM1, pins 3 and 4, which Growatt has set aside for external communication.

Needs an electrician: the inverter has to be opened

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

Applies to: WIT 50-100K-A, -H, -AU and -HU
Connection: Wires in the inverter's terminal 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 50-100K

How the dongle recognises it: The type code 5600 or 5601, or 5603 with a rated power above 15 kW. 5600 appears only in the Home Assistant integration Growatt_ModbusTCP, not in Growatt's own documents, and the sources disagree on which WIT 5601 is.

GridZeno Dongle for Growatt WIT 50-100K

What you need

GridZeno Dongle: The device ID is on the label, e.g. GZ-A1B2C3.
Cable: GridZeno's Modbus cable with one end cut off, or another network cable with one plug.
The 16-pin connector: From the inverter's accessory bag, and a short wire for the bridge between pins 5 and 10.
Tools: Screwdriver for the right cover, and wire strippers.
USB power: A 5 V USB charger and a cable with USB-C.

The port

In the panel on the inverter's right side, behind the right cover, together with BMS-COM (16-pin), COM2 (30-pin), the USB box and DRMS. The matching connector is in the accessory bag.

Port: COM1 (16-pin connector)

The COM1 connector, with Growatt's pin numbering: 1 to 5 at the top, 6 to 11 in the middle and 12 to 16 at the bottom. Pins 3 and 4 are for external communication. The numbers are on the plug.

Pin 3 A, RS485A1
Pin 4 B, RS485B1

The cable

A network cable with an RJ45 plug for the dongle at one end and the other end cut off. At the inverter end, only the two wires from pins 4 and 5 are used. Also a short wire that makes a bridge between pins 5 and 10 in the COM1 connector.

From the dongle to the inverter
Dongle end	Inverter end
Dongle pin 4, blue (A)	COM1 pin 3, RS485A1
Dongle pin 5, white/blue (B)	COM1 pin 4, RS485B1
Short wire	Bridge between COM1 pin 5 and pin 10
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 right cover
Send a shutdown command in the app or on the website first. Then turn off the battery's switch and breaker, then the breaker between the grid and the inverter, and set the DC switches to OFF. Unscrew the right cover so you can see the communication panel.
2
Remove the dust cap from COM1
COM1 is the 16-pin connector in the panel on the right side, between BMS-COM and the large 30-pin COM2. Remove the dust cap.
3
Prepare the cable
Pass the cable in through the hole in the sealing pad, and strip the two wires from pin 4 (blue) and pin 5 (white/blue). Insulate the other wires.
4
Put the wires in pins 3 and 4
Blue (A) goes in pin 3 and white/blue (B) in pin 4 of the 16-pin connector from the accessory bag, following the numbers on the connector. Make a bridge with a short wire between pin 5 and pin 10. That switches on the RS485 resistor, as Growatt specifies when an external device controls the inverter.
5
Plug the connector into COM1
Plug the connector into COM1 so it sits firmly and tightly. Put the right cover back on once all connections have been checked.
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

Pins 6 to 9 are the energy meter's connection, pins 12 and 13 the emergency stop and pins 14 and 15 the generator's start signal. Don't touch wires that are already in them.

Use COM1, not BMS-COM. They have the same shape, but BMS-COM is the battery's connection.

What GridZeno can control on Growatt WIT 50-100K, and how, is on the page about Growatt WIT 50-100K. 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 50-100K Storage/Hybrid Inverter User Manual (GR-UM-299-A-03, EN, 2026-03), Section 3.1, Overview, 6.1, figure 6.1, 6.5.2, External Communication Connection, with table 6.4, and 7.2.1, Set the Communication Address.