PZEM-004T v3
Also known as: PZEM-004T · PZEM004T · Peacefair PZEM · Power & energy
Whole-circuit energy monitoring for a tenner: clamp the CT around a live wire, get volts, amps, watts and kWh into Home Assistant's energy dashboard. The DIY answer to a smart meter.
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At a glance
⚑ flag an error| Measures | voltage, current, power, energy |
|---|---|
| Accuracy | Mains AC V/I/P/kWh/PF/Hz via 100 A CT coil |
| Interface | UART (Modbus; opto-isolated on v3) |
| Supply | 5 V logic side; senses mains |
| Battery-viable | No (continuous draw) |
| ESPHome | Native ESPHome component — pzemac |
| Typical price | $7-11 (street, varies) |
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Which one do I buy?
vs CT clamp + ADC: the PZEM does true power (PF included) and is isolated; a bare SCT-013 into an ADC is cruder. vs Emporia Vue: the Vue does 16 circuits, flashable to ESPHome, at 10x the price.
Clone check
Good for
Gotchas to know
- It touches mains: the sense side connects to live voltage — enclosure, fusing and respect required. If in doubt, buy a finished product.
- v1 vs v3 confusion is the classic support thread; the ESPHome components differ (pzem004t vs pzemac).
- EU users with smart meters: an IR reading head (Hichi/bitShake) reads the utility meter directly and is often the better path.
Wiring it up
Give it a hardware UART (UART1/2 on any ESP32) rather than software serial. Any dev board works; the DevKitC class is the default host, and if you're building a sensor-plus-screen device, pick a display board with spare pins like the JC3248W535.