Installation · Sofar Solar

Install GridZeno on Sofar KTLX.

Sofar KTLX-G3 is a three-phase grid inverter without a battery, so GridZeno can show the production and, where the protocol allows it, limit export. There's no battery to control. The dongle is connected with three wires in the 16-pin COM connector: A in pin 1, B in pin 3 and GND in pin 7.

Applies to: SOFAR 3.3-12KTLX-G3, 3-15KTLX-G3-PRO, 15-24KTLX-G3, 17-25KTLX-G3-PRO, 15-25KTLX-G3P and 15-30KTLX-G3P
Connection: Wires in the inverter's terminal plug
Time: About 30 minutes

A grid inverter without a battery. GridZeno shows solar, consumption and grid and lowers the inverter's export limit at negative prices. What GridZeno can do on Sofar KTLX

How the dongle recognises it: The serial number in holding 0x0445 with the code S1 (15-24KTLX-G3) or S2 (3.3-12KTLX-G3), three-phase.

GridZeno Dongle for Sofar KTLX

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.
Wire strippers and ferrules: Three wire ferrules for the three wires in the COM connector.
USB power: A 5 V USB charger and a cable with USB-C.

The port

On the underside of the inverter, to the right of the USB port. The same connector is used for energy meter and DRM, so there may already be wires in it.

Port: COM (16-pin multifunction connector)

The COM connector, as Sofar numbers the pins. Pins 1 and 2 are A, pins 3 and 4 are B, and pin 7 is the RS485 signal's ground. The numbers are on the plug.

Pin 1 A, RS485A
Pin 3 B, RS485B
Pin 7 GND, GND.S

The cable

A network cable where one end has an RJ45 plug for the dongle and the other end is cut off. At the inverter end, only the three wires from pins 4, 5 and 3 are used, with terminals on.

From the dongle to the inverter
Dongle end	Inverter end
Dongle pin 4, blue (A)	COM pin 1, RS485A
Dongle pin 5, white/blue (B)	COM pin 3, RS485B
Dongle pin 3, white/green (GND)	COM pin 7, GND.S
The other wires	Cut off and insulated

Settings

On the inverter

1.Enter Setting > 7.Set Address: 01, as from the factory
7.Set ComProtocol (PRO, 15-24KTLX-G3 and G3P): Modbus and address 01, as from the factory. On 15-25KTLX-G3P the baud rate is set here: 9600.

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: Sofar Solar, KTLX
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
Check the address
Hold the button down to get into 1.Enter Setting, and go to 7.Set Address. On PRO, 15-24KTLX-G3 and G3P the item is called 7.Set ComProtocol: choose Modbus. The address must be 01, as from the factory. If the display asks for a password, Sofar's default is 0001.
2
Find the COM connector
The round 16-pin connector is on the underside, to the right of the USB port. Switch off the inverter, and take out the connector so you can get at the terminals.
3
Pass the cable through the connector's parts
Pass the cable through the connector's nut and seal before the wires are put in.
4
Prepare the cable
Strip the three wires from pin 4 (blue), pin 5 (white/blue) and pin 3 (white/green), and put terminals on. Insulate the other wires.
5
Put the wires in pins 1, 3 and 7
Blue (A) goes in pin 1, white/blue (B) in pin 3 and white/green (GND) in pin 7, following the numbers on the connector.
6
Plug the connector back in
Screw the connector together, and plug it into the COM port so it's sealed.
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, Sofar Solar KTLX, 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 5 and 6 in COM are the energy meter's connection and pins 8 to 12 the DRM control. Don't touch them. Pin 7 is shared with DRM: if there's already a wire in it, put the dongle's white/green wire in together with it, or leave it out. The USB port is for Sofar's own data logger and for updates.

On 15-25KTLX-G3P there's the item 25.Comm Blackout Config: the inverter switches to a protection mode if RS485 is silent for too long. Leave it turned off, or write to us.

If you aren't used to fitting wires in a terminal connector, let the installer do it.

What GridZeno can control on Sofar KTLX, and how, is on the page about Sofar KTLX. If you're stuck, write to us with the model name.

Source

Ports, pins and menus are from the manufacturer's own manual: SOFAR 3.3~12KTLX-G3 User manual (EN, version 2025-07-18), and the manuals for 3-15KTLX-G3-PRO, 15-24KTLX-G3, 17-25KTLX-G3-PRO, 15-25KTLX-G3P and 15-30KTLX-G3P (EN), Section 4.5.2, COM, Multi function communication port, 4.5.3, Communications Port Description, and Enter Setting (7. Set address).