Build your own Sunpath Bridge

For tinkerers who want to get started before the retail bridge ships.

You can build a fully functional Sunpath Bridge from a few off-the-shelf parts for about £10. It runs the same firmware and has the same features as the retail version — real-time data every 10 seconds, Bluetooth pairing, and automatic updates.

What you need

Part	Approx. cost	Notes
ESP32 DevKit	~£5	Any ESP32 board with a USB port. More options on Amazon.
MAX485 module	~£2	RS485 transceiver module. Usually a small blue or red PCB with screw terminals. More options.
Jumper wires	~£1	5 female-to-female dupont wires to connect the ESP32 to the MAX485.
USB cable	—	Micro-USB or USB-C depending on your ESP32 board. Used for flashing and power.

Wiring

Connect the ESP32 to the MAX485 module with 5 jumper wires:

ESP32 pin	MAX485 pin	Purpose
GPIO 17	DI	Data out to inverter
GPIO 16	RO	Data in from inverter
GPIO 4	DE + RE (bridged)	Direction control — connect both DE and RE to the same wire
3.3V	VCC	Power
GND	GND	Ground

Then connect the MAX485 screw terminals to your inverter's RS485 port:

A terminal → Inverter RS485-A (Data+)
B terminal → Inverter RS485-B (Data-)

Connecting to your inverter

Each inverter brand has the RS485 port in a different place. Find yours below.

Sunsynk / Deye

RJ45 port inside the inverter (you'll need to open the cover). Pin 2 = A, Pin 1 = B, Pin 3 = GND. If your battery uses the same CAN port (Pylontech, Fogstar, BYD), only connect pins 1, 2 and 3 to the bridge — don't use a full straight-through cable.

GivEnergy (Gen 3)

Screw terminals on the bottom of the inverter behind the access panel. Use the EMS bus: Terminal 4 = A, Terminal 5 = B, Terminal 3 = GND. The WiFi dongle uses a separate port, so both can stay connected.

Solis S5

Green 4-pin round connector on the bottom. Pin 3 (yellow wire) = A, Pin 4 (blue wire) = B. Note: this is the same port as the WiFi data logger — the bridge replaces it.

Solis S6

RJ45 port on the bottom. Pin 5 = A, Pin 4 = B. The WiFi stick uses a separate port, so both can stay connected.

Growatt SPH

Use the RS485-2 RJ45 port on the bottom (not RS485-1). Pin 5 = A, Pin 4 = B, Pin 2 = GND. Important: you must enable VPP mode on the inverter display first — hold OK for 10 seconds, navigate to RS485, and change from "Battery" to "VPP".

Flash the firmware

Connect your ESP32 to your computer with a USB cable, then click the button below. The firmware will be written directly from your browser — no software to install.

Your browser doesn't support Web Serial. Please use Google Chrome or Microsoft Edge on a desktop computer. Web Serial requires a secure connection. Please access this page over HTTPS.

Requires Chrome or Edge on desktop. The ESP32 must be connected via USB.

After flashing

The bridge starts in Bluetooth pairing mode automatically. You'll see it advertised as "Sunpath Bridge" on your phone.
Open the Sunpath app and go to Settings → Add Bridge.
Select your bridge, enter your WiFi network name and password.
The bridge connects to your WiFi and starts sending data. You'll see real-time readings on your dashboard within seconds.

Future firmware updates are delivered automatically over WiFi — you won't need to flash again.

Having trouble? Get in touch and we'll help you get set up.