Power-Factor Cost
What low power factor adds to your utility bill, and what correction would recover.
US utilities bill reactive power in a few standard ways, or not at all. Find the clause in your utility’s rate schedule, which it publishes on its website and, if it is investor-owned, files with the state utility commission. Pick it below and put in its numbers. If your rate schedule has no clause, this tool says so; the value of correction at your facility is then in capacity, losses and equipment, not the bill.
Your numbers
Example values. Replace them with yours.
Billing demand adjusted below a threshold: billing demand = metered kW × (threshold ÷ PF) whenever PF is below the threshold; otherwise metered kW. Rate schedules also write this as “the greater of kW or 90% of kVA”, the same rule with a 0.90 threshold.
On the rate schedule, look under “Power factor adjustment”, “Reactive demand” or “Billing demand”. On the bill, look for lines named kVA, kVAR, kVARh, “PF adj” or “reactive”.
The bill’s demand line (“kW”, “Demand”, “Max demand”) for a typical month.
From the bill if it prints one (“PF”, “Power factor”); otherwise from the Power Factor Check. Use the peak-period value if the bill gives one.
The power factor named in the clause: “below 90%” is 0.90, “less than 0.95” is 0.95.
The demand charge per kW per month on the rate schedule. If it has seasons or tiers, use the one on your last bill.
12 unless the clause is seasonal, or your peak only breaches the threshold in some months.
0.98 is what both manufacturers rate their equipment to reach (Accentz: 0.98–0.99; Trans Power: up to 0.98). The measured case on our results page reached 1.00.
Results
$8,429
- Charged for low power factor now
- $702 a month$8,429 a year over 12 months
- After correction at 0.98
- $0 a month
- Saving per month
- $702
- Billing demand
- 527 kW now480 kW after
At 0.82, your 480 kW peak bills as 527 kW: the rate schedule scales demand by 0.90 ÷ 0.82 when power factor is below 0.90. At 0.98 it would bill as 480 kW. At $15.00 per kW, the difference is $702 a month, about $8,429 a year over 12 months.
The coloured segment is what the clause adds for power factor.
How this is calculated
Billing demand adjusted below a threshold: billing kW = metered kW × threshold ÷ PF when PF is below the threshold. Demand in kVA: kVA = kW ÷ PF. Charge per kVAR: reactive demand kVAR = kW × tan(acos PF), less the allowance. Charge per kVARh: the bill’s kVARh, less an allowance of kWh × tan(acos threshold). Percentage per point: the demand charge × the percentage × the points below the threshold. In each case the tool works the clause at your power factor now and again at the target, and the difference is what correction recovers, times the months the clause applies.
Assumptions
- One power factor stands for the whole month; utilities differ on whether they use the peak interval, the monthly average or lagging reactive only, and your rate schedule decides.
- Rates and thresholds are yours to enter; the defaults are placeholders, not any utility’s rates.
- Real kW demand is unchanged by correction; only the billing basis moves.
Estimates from your inputs and the formulas shown. They are not a ruling from your utility, a design or a guarantee. A survey and the six-month rental measure the real thing on your own meter.
Your numbers go with your request; nothing is sent until you submit the form.