On Tue, 30 Aug 2016 08:55:00 +0100, dennis@home wrote:

Currentcost doesn't measure power only current and it estimates power.
Do you correct it using the voltage info from the UPS?

It's close enough, 1kWHr error per day on 20+ KWHrs of consumption.
The coupling betwen tails and current transformer is the source of
the error not the voltage which here is 240 +/- 5V absolute maximum.
Unless the local primary substation is on the backup feed when it
goes from 230V up to 255+ (yes out of tolerance.

A Pi can do it without the currentcost if you buy a cheap current sensor
or time the pulses from the meter if it has the LED.

Needs some form of buffering and AD convertor, doesn't provide the
realtime display without adding one.

--
Cheers
Dave.