The “Energy to yesterday” originally had two functions.
Firstly to obtain the energy used today when you first set up the ESPproMon app. Energy today is simply cumulative energy used less what was used up to midnight last night. So when you first set up the app all the cumulative energy on the Pzem meter would be shown incorrectly as today’s usage if you don’t define the usage up to midnight yesterday.
If users don’t allocate a cumulative usage to midnight yesterday when they first set up the app the current day usage will be corrected at midnight following the first day’s usage.
Secondly it was designed for cheaper monitoring systems where a reboot of the “meter” loses all the data i.e. the ACS712 and Open Energy Monitor hardware.
The Pzem has the benefit of retaining energy usage after a reboot but the problem is that unless you power up the Pzem at exactly the same time as your physical electric meter is installed they will always be out of sync.
So the idea is that you only sync the data based on each meter reading by the electric company. That is on the day the meter is read you physically go through the reset procedure (not a simple reboot) of the Pzem. Then the app is in sync for your current billing cycle. Hope that makes sense.
Could you expand on this.
We don’t currently have any plans to hook up more than one meter as we are guessing that 99% of households only have a single meter.