Smart Meter Quick Start Guide


These two are set in the TARIFF page with parameters 13 and 12 respectively. Once you select each parameter you enter a value in the Terminal. In your case it will be zero for both but for some users they might set particular values to match the data to their physical electric meter etc.


This is hard wired to the Pzem.

What I mean by this is that you would need to clear the cumulative energy used in the Pzem and then the app will automatically have the correct value.

You probably don’t need to do this now but some users reset their Pzem after they receive each bill.

The Pzem reset procedure is covered elsewhere on this site but as a quick recap it’s power off the WeMos, press the reset button on the Pzem and then press the reset button again on the Pzem.

Pzem reset will not work if the WeMos is powered up and connected to the Pzem.


When trying to set these parametersAt a certain point in time I might want to do this. For now, what interests me most is to see daily Kwh usage. Calibrating with my “real” meters is hard because I actulaly have 4 different “counters” :

  • High Rate consumption (Day)
  • Low Rate consumption (evening/nights/weekends)
  • High Rate injection (from Solar Panels)
  • Low Rate injection


We can look at multiple meters etc moving forward.

Notice your public dashboard at EmonCMS is not updating, have you entered the API key against the EmonCMS paramater (not the Thingspeak parameter)?


Tried several times now to se API key but what happens is it seems to “reset” showing following screen but not asking to actually enter the API key :


When the system reboots the cost will be shown as €0.00 and you will see the Set API details prompt until it’s been running for 3 minutes. Then it will show the correct cost and that the API key has been entered if you have already set the correct key.


Do you think you have entered the correct read and write key?


So when it says (like in screenshot above) “Enter API key” then I should enter the EMonCMS API key ? The text should say something likje “17 - Enter EmonCMS API key :” … since it’s that parameter you want to set and so as to not confuse the user :slight_smile:

Correction … Indee after 3 minutes or so it asks for EmonCMS API key … Was confusing during those first 3 minutes …

I have set the key now …


Yes but that bootup message is actually incorrect as it will always say that even when you have entered the correct key. It’s because it hasn’t read the data from our server when it first boots up.

I will look to change this on a future update.

Still not seeing your dashboard update. Are you still using the same dashboard?


Correct … Not seeing changes either … Still using the same API key as before … Will double check …


Are you entering a key that starts with 9 and ends with 4?


Yes correct … just checked and it’s te right read/write key …

Got message “API key is now set”


Dashboard is updating now.


Right !! :slight_smile:
Value “Since Last bill” is still not zero but so that’s the PZEM reset I would need to do … Will leave it as is for njow …Energy to Yesterday and Cost to Yesterday are not reset to zero either …

What’s the difference with the"RESET COST" button ??



After you selected those parameters in the TARIFF page did you enter zero for each parameter in turn?

I will have to check the code for this as I can’t remember exactly what it does :slight_smile:


After you selected those parameters in the TARIFF page did you enter zero for each parameter in turn?
-> Was not asked to do so

Correction : now I was able to … apparently setting parameters does not always work … Sometimes the question is not asked after pressing OK

I see now that you often have to repeat the process multiple times before you have the chance to enter something for a parameter

What about “Period Cost” ?


Possibly just a delay between your WeMos and the server or the WeMos is busy reading the Pzem values. But you were asked to enter the details here:


What about “Period Cost” ?
-> This one is not in the parameter selection as far as I can see …


This is the cost since the Pzem had it’s last reset and all done in the firmware i.e. no parameter setting required.


Okay …

Really love the App … Still some work to be done, especially on clear documentation, it is a bit dispersed right now. Have you considered commercialising this through Kickstarter or Indiegogo ? Would love to help !

What’s the difference between Apparent Power & Real Power ?