# PZEM-004T AC energy monitor: specs

> A single-phase AC measurement module for voltage, current, active power, frequency, power factor and energy; the 100A version uses an external…

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A single-phase AC measurement module for voltage, current, active power, frequency, power factor and energy; the 100A version uses an external current transformer. It connects to mains. The maker page title for the series says 'TTL Modbus'. Figures below are from the maker's PZEM-004T product page.

Every value cites its sourcePinout not published

[Buy on Compoden](https://compoden.com/products/pzem-004t-ac-energy-monitor-module-100a-modbus-rtu)

## Specs

| Spec | Value | Source |
|---|---|---|
| Voltage measuring range | 80 V to 260 V, resolution 0.1 V, accuracy 0.5 % | source Product description, Measurement range |
| Current measuring range (100A model) | 0 to 100 A with an external transformer; starting current 0.02 A; resolution 0.001 A; accuracy 0.5 % | source Product description, Measurement range |
| Active power range (100A model) | 0 to 23 kW; starting power 0.4 W; resolution 0.1 W; accuracy 0.5 % | source Product description, Measurement range |
| Active energy | 0 to 9999.99 kWh, resolution 1 Wh, accuracy 0.5 %; reset by software | source Product description, Measurement range |
| Frequency | 45 Hz to 65 Hz, resolution 0.1 Hz, accuracy 0.5 % | source Product description, Measurement range |
| Power factor | 0.00 to 1.00, resolution 0.01, accuracy 1 % | source Product description, Measurement range |
| Communication | TTL interface over UART: 9600 baud, 8 data bits, 1 stop bit, no parity | source Product description, Communication interface and Physical layer protocol |

## Pinout
We don't publish a pin table for this part: no official source we could verify gives one. Check the labels printed on your module, and see the notes below.

The maker page does not list terminals or header pins. Mains terminals and the TTL header are not documented here.

## Build with it
Project ideas for the PZEM-004T AC energy monitor. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.

- [Energy readout on an OLED](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20mains%20energy%20readout%20that%20reads%20a%20PZEM-004T%20over%20serial%20and%20shows%20watts%20on%20an%20OLED%20using%20an%20ESP32): Learning project for the logic side only: the mains connection and the transformer clamp are installed by a qualified person in the enclosure. The TTL-side supply and signal level are not documented on the maker page, so this idea assumes nothing about them: measure them before wiring, and add a level converter only if the measured level needs one. The TTL side needs its own supply; find its voltage on the module before wiring (not documented on the maker page).
- [A web page that shows power and energy readings from a PZEM-004T using a NodeMCU ESP8266](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20web%20page%20that%20shows%20power%20and%20energy%20readings%20from%20a%20PZEM-004T%20using%20a%20NodeMCU%20ESP8266): The ESP8266 reads the serial values and serves them on the local network. Mains wiring is not a beginner task: have it done by a qualified person. The TTL-side supply and signal level are not documented on the maker page, so this idea assumes nothing about them: measure them before wiring, and add a level converter only if the measured level needs one. The TTL side needs its own supply; find its voltage on the module before wiring (not documented on the maker page).
- [Energy readout on a 16x2 LCD](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20mains%20energy%20display%20that%20shows%20volts%20and%20watts%20on%20a%2016x2%20LCD%20using%20an%20Arduino%20Uno%20and%20a%20PZEM-004T): The Uno reads the module over a serial link; the mains side is wired by a qualified person. Compare the readout with the ranges on the maker page. The TTL-side supply and signal level are not documented on the maker page, so this idea assumes nothing about them: measure them before wiring, and add a level converter only if the measured level needs one. The TTL side needs its own supply; find its voltage on the module before wiring (not documented on the maker page).

## Common mistakes

- This module is connected to mains voltage. Wiring the mains side must be done by a qualified person, inside an enclosure; do not touch the module while it is connected.
- The 100A model measures current through an external transformer, not a built-in shunt (the 10A model has the built-in shunt) (source: [link](https://en.peacefair.cn/product/772.html), Product description).
- The voltage range is 80 V to 260 V; the maker page does not state the TTL signal level, so check it with a meter before connecting to a 3.3 V board ([source](https://en.peacefair.cn/product/772.html)).

## Not covered by the official source

- The maker page lists the 100A model as PZEM-004T 4.0 and the 10A as 3.0; the product name does not say which hardware version is stocked.
- The maker page title says TTL Modbus; the page body does not give a register map or the word RTU, so the protocol details are not verified here.
- Module supply voltage, TTL signal level, terminal layout and isolation are not stated on the maker page, so the ideas below assume nothing about them.
- No downloadable maker manual was found.

## Sources

- [link](https://en.peacefair.cn/product/772.html) (Peacefair PZEM-004T 4.0 product page, listed 2024-07-04)