Utility power factor clauses determine whether low power factor adds a surcharge, increases billed demand, or raises a kVA-based demand charge. There is no universal penalty for falling below 0.90: the applicable rate schedule controls the threshold, measurement period, formula, and charges affected. A facility at 0.75 power factor can therefore face very different billing consequences under different utility clauses.
Utility Power Factor Clause Comparison
| Clause type | Threshold or billing basis | Effect at 0.75 power factor | Information needed to calculate the cost |
|---|---|---|---|
| Percentage surcharge | A utility-defined power factor band and eligible charge subtotal | BC Hydro’s published schedule assigns a 16% surcharge at 0.75 for applicable customers in British Columbia, Canada; residential rates are excluded. | Billing-period power factor, surcharge band, and charges included in the surcharge base |
| Adjusted kW demand | Measured kW multiplied by a reference power factor divided by actual power factor | Dover, Delaware’s July 2025 C5 schedule uses (0.95/0.75), increasing the demand quantity by approximately 26.67% before minimum-bill provisions..pdf) | Applicable reference factor, measured demand, tariff-defined power factor, USD/kW rate, and demand minimums |
| kVA demand billing | Apparent demand, rather than unadjusted real-power demand | At the same load and interval, 100 kW at 0.75 PF corresponds to approximately 133.33 kVA; a separate penalty line is not necessary for power factor to affect the charge. | Metered kVA demand, USD/kVA rate, demand interval, and any ratchet or minimum |
These are different billing mechanisms, not interchangeable penalty formulas. The BC Hydro percentage is specific to its published schedule; the Dover formula above is identified by its actual document year. Neither is a national benchmark or a substitute for the rate schedule serving your property.
Why a Power Factor Adjustment Appears on the Bill
Power factor is the ratio of real power to apparent power:
[
PF=\frac{P}{S}
]
Here, (P) is real power in kW, (S) is apparent power in kVA, and PF is dimensionless. For matching measurements, rearranging gives:
[
S=\frac{P}{PF}
]
A lower power factor means more apparent power is required to supply the same real-power load. Utilities may recover the associated capacity and reactive-power costs through a surcharge, adjusted billing demand, or apparent-demand billing. BC Hydro specifically explains that its surcharge recovers reactive-power supply costs not included in its other charges.
This distinction matters when reviewing savings claims. A reduction in billed demand is not the same as an equivalent reduction in kWh consumption. Demand charges and energy charges measure different things, and the power factor clause determines which part of the bill changes.
Read the Applicable Clause Before Choosing a Formula
Start with the rate code printed on the bill, not a generic utility rate found online. Even within one utility, service classes can use different reference factors, demand intervals, and minimum-bill provisions. Dover’s July 2025 schedules, for example, specify a 0.95 reference factor for C5 and primary service, but 0.985 for transmission service..pdf)
Use this sequence to extract the billing rules:
1. Identify the utility, service territory, rate code, and effective dates covering the bill.
- Find the sections titled “Power Factor,” “Determination of Demand,” “Billing Demand,” or equivalent.
- Record the power factor threshold or reference factor, including treatment of leading and lagging power factor.
- Identify the measurement basis: billing-period average PF, a specified demand interval, or another tariff-defined method.
- Identify the affected charge: an eligible bill subtotal, adjusted kW demand, kVA demand, or reactive demand.
- Read minimum-demand, historical-demand, rounding, and rider provisions before calculating the final bill.
The last step can change the result substantially. Dover’s July 2025 C5 schedule includes a minimum-bill demand component based on 60% of the greatest billing demand established during its specified 11-month period. Lowering this month’s calculated demand does not necessarily lower the amount payable by the same proportion..pdf)
Official Clause Wording and Document Dates
BC Hydro’s published billing explanation states that surcharge percentages are “applied to the total of all other charges for the same period.” That wording identifies the surcharge base; it does not describe a multiplier applied only to the demand charge. Its schedule places a PF of exactly 75% in the 16% band, while values below 75% and at least 70% fall in the 24% band.
Dover’s July 2025 C5 schedule states:
“Billing Demand = Measured demand X.95 / Average Power Factor.”.pdf)
That schedule also says the adjustment applies when average power factor is greater or less than 95%, and that the city measures both leading and lagging power factor. Do not rewrite this particular clause as a penalty-only formula with an automatic floor at measured kW..pdf)
For current Dover accounts, the official utility-services page identifies approved 2026 tariffs as “Rates & Tariffs FY ’27.” The separate electric-rate summary applies to bill dates on and after July 1, 2026 and lists a Large Commercial demand rate of USD 15.11/kW. Use the complete applicable tariff to establish the power factor rule; the rate summary alone does not establish that formula.
Parameters Needed for a Reproducible Calculation
| Parameter | Symbol or unit | What to obtain |
|---|---|---|
| Actual power factor | (PF_a), decimal | Utility-defined PF for the relevant billing period or interval |
| Reference power factor | (PF_t), decimal | Threshold or adjustment reference stated in the tariff |
| Measured real-power demand | (P), kW | Demand reading specified by the rate schedule |
| Apparent-power demand | (S), kVA | Utility demand reading when the account uses kVA billing |
| Demand rate | (R), USD/kW or USD/kVA | Rate applicable to the billing period and charge component |
| Surcharge percentage | (s), decimal | Exact tariff band or calculation rule |
| Eligible charge subtotal | (B), USD | Charges to which the surcharge applies |
| Minimum or ratcheted demand | kW or kVA | Applicable tariff floor and relevant demand history |
| Measurement interval | Minutes | Interval specified by the utility |
Enter 75% as 0.75 when a formula expects a decimal. Keep units attached to every demand rate: USD/kW and USD/kVA are not interchangeable.
For the physical relationship (S=P/PF), kW and PF must describe matching operating conditions. A monthly-average PF and an unrelated maximum kW reading should not be combined to reconstruct a peak kVA measurement unless the tariff expressly specifies that calculation. The utility’s prescribed billing formula takes precedence over an improvised reconstruction..pdf)
Hand Calculation: 0.75 PF Under a 0.90 Demand-Adjustment Clause
The following is a hypothetical U.S. commercial-account example, not an actual utility rate or national average. Assume the clause adjusts demand below 0.90 using the reference-to-actual PF ratio, provides no adjustment above the threshold, and has no binding minimum or ratchet for this bill.
| Input | Assumed value |
|---|---|
| Measured demand | 100 kW |
| Actual PF | 0.75 |
| Reference PF | 0.90 |
| Demand rate | USD 15.00/kW per billing month |
| Calculation scope | Demand charge only; taxes, riders, energy charges, and fixed charges excluded |
A government-hosted utility-bill analysis presentation illustrates this reference-factor adjustment method. The values here are deliberately assumed so the arithmetic can be checked independently.
Calculate Adjusted Demand
[
D_{\text{adjusted}}=P\times\frac{PF_t}{PF_a}
]
[
D_{\text{adjusted}}
=100\text{ kW}\times\frac{0.90}{0.75}
=120\text{ kW}
]
The multiplier is 1.20. The adjustment adds 20 kW to the demand quantity used for this charge.
Calculate the Demand-Charge Increase
Without the PF adjustment:
[
C_{\text{unadjusted}}
=100\text{ kW}\times15.00\text{ USD/kW}
=1{,}500.00\text{ USD}
]
With the PF adjustment:
[
C_{\text{adjusted}}
=120\text{ kW}\times15.00\text{ USD/kW}
=1{,}800.00\text{ USD}
]
The incremental charge is:
[
\Delta C
=1{,}800.00-1{,}500.00
=300.00\text{ USD}
]
The result is a USD 300.00 increase in the modeled monthly demand charge, or 20% of its unadjusted amount. It is not a 20% increase in the entire electricity bill. The utility might incorporate the adjustment into billed demand rather than display a separate “power factor penalty” line.
The Power Factor Penalty Calculator should be used for this comparison only if its supported calculation mode matches the applicable clause. Check its formula, input units, and treatment of thresholds against the hand calculation rather than assuming every utility uses the same method.
Compare Surcharge and kVA Billing at the Same Power Factor
Percentage Surcharge
For a percentage-based clause:
[
C_{\text{PF surcharge}}=B\times s
]
As a separate hypothetical U.S. billing example, assume an eligible subtotal of USD 1,500.00 and a tariff-defined surcharge of 16%:
[
C_{\text{PF surcharge}}
=1{,}500.00\text{ USD}\times0.16
=240.00\text{ USD}
]
The subtotal including that surcharge becomes USD 1,740.00. The 16% is an assumed percentage for this USD example, not a claimed U.S. tariff rate. BC Hydro’s actual published schedule uses that percentage at 0.75 PF for applicable British Columbia accounts, but its rules and account currency must be used when calculating a real BC Hydro bill.
This example explains why the surcharge base matters. Applying 16% to only a demand charge produces a different amount from applying it to all eligible charges.
kVA Demand Billing
For a hypothetical U.S. account billed at USD 15.00/kVA per month, assume a matching demand interval with 100 kW at 0.75 PF and no binding demand floor:
[
S=\frac{100\text{ kW}}{0.75}
\approx133.33\text{ kVA}
]
Using the unrounded value:
[
C_{\text{kVA}}
=\frac{100}{0.75}\times15.00
=2{,}000.00\text{ USD}
]
At unity PF, the same 100 kW would correspond to 100 kVA and a USD 1,500.00 charge under these assumptions. The difference is USD 500.00, or approximately 33.33%, relative to that unity-PF comparison.
There is no assumed 0.90 exemption in this model. A kVA-based charge can respond to changes in apparent demand without a separately labeled PF penalty. Actual billing depends on the utility’s metered demand interval and tariff provisions.
A 0.90 power factor threshold does not mean “10% of the bill,” and a 0.75 power factor does not mean “25% wasted electricity.” Calculate the consequence from the applicable surcharge, demand-adjustment, or kVA-billing rule—not from the distance between PF and 1.00.
Evaluate Correction Against the Billing Mechanism
Establish the billed consequence before selecting correction equipment. Under a threshold surcharge, crossing into a lower band may change the charge in steps. Under adjusted-demand billing, the reference-to-actual PF ratio changes the demand quantity. Under kVA billing, the relevant result is the reduction in metered apparent demand, subject to billing minimums.
Correction also depends on the cause. BC Hydro identifies capacitors as a possible solution for linear inductive loads, harmonic filters for some nonlinear loads, and operational changes such as operating motors closer to their full-load rating. It recommends qualified electrical contractors for correction services.
Do not treat a billing calculation as capacitor sizing or installation approval. Equipment selection still requires assessment of load variation, harmonics, leading power factor, protection, manufacturer instructions, and applicable electrical requirements. The calculator and examples do not replace NEC requirements, the local AHJ, or qualified site-specific judgment.
Power Factor Bill-Review Checklist
Use this checklist to Verify the inputs before accepting a penalty estimate or correction-savings proposal.
- The utility, service territory, rate code, and effective dates match the bill.
- The clause type is identified: surcharge, adjusted kW, kVA demand, or another specified mechanism.
- The threshold, reference factor, and band boundaries come from the applicable official schedule.
- The PF value follows the utility’s measurement definition.
- The demand reading, measurement interval, and rate units are correct.
- The eligible surcharge subtotal includes exactly the charges specified.
- Leading-PF provisions, rounding rules, minimums, and demand ratchets have been checked.
- The hand calculation reproduces the relevant billed charge or adjustment.
- Estimated savings change only the charges affected by the modeled improvement.
- Any equipment proposal has a separate qualified electrical assessment.
Keep the applicable tariff and bill together with the calculation. That record makes the result reproducible and prevents a generic 0.90 threshold or example rate from being mistaken for the rule governing the facility.