Shelly 1PM Gen3

← README · All devices · Commands

🧰 Before you start · ⚙️ Config · ⚡ Flash it · 👀 What to expect · ↩️ Way back

Gen3 / ESP32-C3.

Fact	Value
Profile	S1PMG3
Flash	8 MB
Official package	2.1.0
Partition table	0xf000
App slot size	0x2c0000
ESPHome device page	Shelly 1PM Gen3

Before you start

Check first:

• the device runs Shelly's own firmware, not ESPHome yet
• you know its IP address (--ip), or this PC is on the device's own access point (default 192.168.33.1)
• the device can reach this PC: same network, port 8000 (--port) not blocked
• your ESPHome config uses the partition table below and is compiled
• a UART adapter is at hand as your way back (Recovery over UART)

ESPHome config

Important

build refuses a config without Shelly's partition table. Copy partitions/S1PMG3-stock.csv from this repository next to your YAML and keep CONFIG_PARTITION_TABLE_OFFSET: "0xf000".

esp32:
  variant: ESP32C3
  board: esp32-c3-devkitm-1
  flash_size: 8MB
  partitions: S1PMG3-stock.csv        # copy from partitions/ in this repository
  framework:
    type: esp-idf
    sdkconfig_options:
      CONFIG_PARTITION_TABLE_OFFSET: "0xf000"
    advanced:
      enable_ota_rollback: false

ota:
  - platform: esphome
    allow_partition_access: true

Tip

The ESPHome device page has a config to start from. Replace its esp32: block with the one above, or build refuses it.

Flash it

1. Install the requirements (once):

pip install -r requirements.txt

1. Fetch the official package:

python ota.py fetch S1PMG3 --insecure

1. Build: put your app into it; the ZIP goes to out/:

python ota.py build S1PMG3 app.ota.bin --esphome-factory app.factory.bin --esphome-yaml app.yaml

1. Check the device first. Nothing is sent:

python ota.py send S1PMG3 out/S1PMG3-app-<date>.zip --ip <device IP> --dry-run

1. Flash it and watch the log:

python ota.py send S1PMG3 out/S1PMG3-app-<date>.zip --ip <device IP> --watch 120

app.ota.bin and app.factory.bin are the two files ESPHome compiles. --dry-run only checks the device and, for this package, reads the update target slot. Command reference: Commands.

What to expect

In the --watch log look for these lines, in this order:

#	Log line	Meaning
1	Update target slot: 0 ...	The slot check of send. Anything else: run python ota.py restore S1PMG3 first
2	Boot: cur ... min ... update? 1	The installer will write ESPHome's bootloader. update? 0 means it will not: build again with a higher --boot-min-version (why)
3	ota_progress up to 95 %, then ota_success	The device restarts into ESPHome

Notes for this device

First report (thanks to WulffTech): one unit (S3SW-001P16EU) went from Shelly 2.0.1 to ESPHome 2026.9.0 over OTA without UART, using their own tooling with the same package mechanism, not ota.py. It ran stable across reboots, the relay stayed off after them, and a later ESPHome OTA worked. Their image checks match ota.py's (header checksum and appended SHA-256) and the install went through without warnings. The meter and the relay under load were not reported.

• Not run with ota.py: the slot check, the bootloader comparison and the boot_min_version step of this project are not confirmed on this device. Please report the --watch log, especially the lines Update target slot, Boot: cur ... update? and Will write to slot.

The profile sets boot_min_version: "1.0.9": devices of this family run Shelly's loader 1.0.3, which would otherwise skip ESPHome's bootloader (update? 0).

Way back

python ota.py restore S1PMG3 sends the official firmware back while Shelly firmware still runs.

---

Warning

• Wipes Wi-Fi and settings. ESPHome opens its own access point or joins the Wi-Fi from your config; if nothing comes up, power-cycle the device (help).
• No way back over the network once ESPHome's bootloader runs: restore gets no answer, only UART brings Shelly OS back (Recovery over UART). Take a flash backup first if you can.
• Flashed it? Tell us, also when it worked: open a device report.

Bootloader and slots · Troubleshooting · Recovery over UART