Installation · Sofar Solar

Install GridZeno on Sofar ESI.

Sofar ESI is a single-phase hybrid inverter with a battery. It has a 20-pin multi-function connector, COM, where pins 2 and 3 are Sofar's own RS485 connection for monitoring the inverter. The dongle is connected with two wires in those two pins.

Needs an electrician: the inverter has to be opened

The inverter has to be opened to reach the communication port, and behind the cover there are also high-voltage connections. It should be done by a qualified person, such as an authorised electrician.

Applies to: ESI 3-6K-S1
Connection: Wires in the inverter's terminal plug
Time: About 30 minutes

What GridZeno can do on Sofar ESI today

There's no public register map for the ESI 3-6K-S1, so the dongle can't read it yet.

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You can connect the dongle by this guide, but it reads nothing from the inverter until its firmware can. GridZeno Dongle for Sofar ESI

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 stripper, ferrules and a small flat-blade screwdriver: Two wire ferrules, and the screwdriver for the terminals in the COM connector.
USB power: A 5 V USB charger and a cable with USB-C.

The port

On the right-hand side of the inverter, below the connectors for grid and EPS (Inverter signal port). The same connector is used for the battery, energy meter, current clamp and DRM, so there may already be wires in it.

Port: COM (20-pin multi-function connector)

The COM connector, with the pins numbered as Sofar numbers them. Pins 2 and 3 are for monitoring the inverter, pins 6 and 7 for the energy meter. The numbers are on the plug.

Pin 2 A, UC-A
Pin 3 B, UC-B

The cable

A network cable where one end has an RJ45 connector for the dongle and the other end is cut off. At the inverter end, only the two wires from pins 4 and 5 are used, with terminals (wire-end ferrules) on them. The COM connector has no RS485 GND, so the white/green wire isn't used.

From the dongle to the inverter
Dongle end	Inverter end
Dongle pin 4, blue (A)	COM pin 2, UC-A
Dongle pin 5, white/blue (B)	COM pin 3, UC-B
The other wires	Cut off and insulated

Settings

On the inverter

System Setting > 7. Communication Addr.: Read off Communication Addr. and Baud Rate. The dongle must have the same.

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, ESI
Connection: By cable (RS485)
RS485 settings: The same baud rate and address as the inverter, 8N1.

Step by step

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

1
Read off the address and baud rate
In the display, go to System Setting and 7. Communication Addr. Here you find 1. Communication Addr. and 2. Baud Rate. Note down the address and the baud rate: the dongle must have the same.
2
Take the cover off
Switch the system off as the manual describes, and take off the outer cover over the connections so you can reach the COM connector.
3
Find the COM connector
The 20-pin connector is on the right-hand side of the inverter, below the connectors for grid and EPS. Pull it out, and unscrew the locking nut.
4
Pass the cable through the connector's parts
Pass the cable through the locking nut and the rubber insert. Take the plug out of the hole the cable is to go through, and leave the other plugs in place.
5
Prepare the cable
Cut off one end of the cable, strip 7.5 mm of the two wires from pin 4 (blue) and pin 5 (white/blue), and fit ferrules. Insulate the other wires.
6
Put the wires in pins 2 and 3
Blue (A) goes in pin 2 and white/blue (B) in pin 3. Tighten the screws, and don't touch wires already in the other pins.
7
Plug the connector back in
Press the rubber insert into the connector until it clicks, and screw the locking nut on. Plug the connector into the COM port, and put the cover back on.
8
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.
9
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.
10
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.
11
Log in, and choose your inverter
Log in to GridZeno. Welcome pairs the dongle with its device ID. Then choose your inverter, Sofar Solar ESI, and the connection By cable (RS485). Set the inverter's address and baud rate under RS485 settings. 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 only pins 2 and 3 in COM. Pins 4, 5, 8 and 9 are the battery's connection, pins 6 and 7 the energy meter's, pins 18 and 19 the current clamp's, and pins 12 to 17 are used for DRM. Link Port 0 and 1 are for inverters in parallel, and the WIFI/4G port is for Sofar's own logger.

If there are several inverters in a chain on pins 2 and 3, each must have its own Communication Addr. Write to us before you connect the dongle to such a system.

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

Sofar ESI isn't on the compatibility list yet. If you're stuck, write to us with the model name.

Source

Ports, pins and menus are from the manufacturer's own manual: Sofar ESI 3-6K-S1 User Manual (EN, Issue 01, 2025-08-28), Sections 5.4.5, COM-Multi function communication connection (table 5-2 and figure 5-22), and 6.4.1, System Setting, Communication Addr..