Multiply your voltage by your
current instant by instant, take the average (gives you power) and
multiply that by the duration in hours and you have your consumption.

They don't bill me instant-by-instant; they bill me for the power they
claim I've used over the course of a three-monthly period. Since power
is the product of voltage and current (and I've proved earlier that
both are zero)
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As commented before in this thread you are billed for 'energy' NOT power.

Frank GM0CSZ / KN6WH