Resetting the PeaceFair PZEM-004T


One useful feature of the PeaceFair PZEM-004T is that it will retain energy usage data even if you have a power failure. You could just let the KWH increase month by month up to the maximum of 9999 KWH but the assumption is that you will reset the value each time you receive an electric bill.

We received our bi-monthly invoice, via email, from the electricity company today so we went through the reset procedure for the PeaceFair PZEM-004T and the ESPproMon smartphone app.

The image above was the PZEM-004T before the reset and the image below the ESPproMon smartphone app at the same time i.e. with cumulative KWH of 619.2.

Just above the text of kWh on the PZEM-004T there is the black reset button. As per the documentation you should have received from PeaceFair the procedure to reset the energy used to date is as follows:

  1. Long press on the reset button for 5 seconds until the digits for kWh flash on and off.
  2. Short press on the reset button and the kWh will be set at zero.
  3. If you don’t want to reset the energy, skip the short press and the reset function will be ignored.
  4. IMPORTANT - the reset procedure will only work if the TTL port is not being used. So you have 2 options, either disconnect the 4 way cable between the PeaceFair PZEM-004T and the ESP8266 or simply power off the ESP8266 before you start the reset process.

Your PZEM-004T should now show something like this:

In the smartphone app you might now want to reset the cost and KWH for yesterday to 0 by selecting parameters 12 and 13, on the tariff page, in turn and entering 0 in the Terminal.

It’s not critical that you manually zero the cost and KWH for yesterday as the values will be automatically rolled over at midnight from the corresponding figures for today.