SPM-4Relay specifications
- Connectivity – RS485
- Power Input – 100-240V 50/60Hz up to 20A per relay, 80A total
- Power Output – 100-240V 50/60Hz up to 20A per relay, 80A total
- Safety – Current, voltage, and power overload protection with delay function from 0 to 180 seconds to avoid false positives
- Dimensions – 250 x 90 x 66.5 mm (PC V0 material)
SONOFF Smart Stackable Power Meter works with the usual eWelink app for Android and iOS to allow you to visualize the data which can also be stored in a MicroSD card. There’s also an HTTP API to read the data, which should eventually be documentation on the developer’s website. I suspect the solution may soon end up being supported by ESPHome or Tastoma open-source firmware projects provided it is indeed based on ESP8266 or ESP32 chip.