Pow r3 accuracy

Hi, I need some help… I have Pow R3 to control my electric car charge, and after checking the consumptions, it happens Electricity bill says I have consumed 414Kw/h and pow r3 says I have consumed 520kw/h for the same period!!!

I can´t trust pow r3 then so it is a big problem. Any ideas how to calibrate it to make it measure real consumption??


So big gap! dose the power bill always less then the R3 calculation or sometimes it more then it?
Better to ask SONOFF team how the calculate works, i will forward this issue to them too.