One or Two PFs?

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BR549

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Boise
Assume a net-metered facility that during a month, there are times when the facility is producing energy into the grid and times when the facility is consuming energy from the grid. This assumes the facility is large enough that the power factor (PF) is included in their billing calculation.

For such a case, do utilities calculate two PF's for a month (one for generation, one for consumption) or just one? If a single PF is calculated, how is it calculated?
 

robbietan

Senior Member
Location
Antipolo City
Assume a net-metered facility that during a month, there are times when the facility is producing energy into the grid and times when the facility is consuming energy from the grid. This assumes the facility is large enough that the power factor (PF) is included in their billing calculation.

For such a case, do utilities calculate two PF's for a month (one for generation, one for consumption) or just one? If a single PF is calculated, how is it calculated?

when you generate power, you are only billed for energy delivered, no PF is involved. when you are consuming energy (and here I assume you are large enough a consumer to be billed for VARs or have pf discounts/penalties) you pay for the energy consumed plus the impact of your loads to the grid.

all in all, only one PF, for your consumption
 

mivey

Senior Member
It would normally be one PF. It is usually the highest kvar measured compared to the highest kW measured but can also be based on the kvarh for the month compared to the kWh for the month. There may be exceptions when we look at the interval delivered and received data to compare the kWh & kvarh and make adjustments (where we have meters that store the interval data).

Usually a small user can get away with gaming the system a little as it is not worth the utility chasing it but the bigger users will be monitored more closely. Letting the system hit a high kW demand in order to reduce the PF penalty will usually not help you because the demand charges for that higher kW will compensate the utility.

Some utilities even have rates that charge demand based on kVA instead of kW.

Imagine the extreme case where you are generating exactly the kW you need during all periods. The vars you need will still come from the utility and they will charge you per the rate. Most of the generators are set to carry some of the var load as well. The utility may even require that you carry some var load with your units.
 
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