The amount on the bill does not come from units alone. A bill is made up of the energy charge at the tariff rate, the Ft charge and VAT. Units can stay the same while the total rises from other lines — for example an Ft that falls in a different period in the two months, a demand charge measured from the highest short interval rather than total units (only for tariff types that charge for demand), a minimum charge anchored to a month that once spiked, a power factor charge, a customer category that has been moved, or a larger share of units in the On Peak period if the TOU rate is used.
The rule figures in this article come from the Provincial Electricity Authority (PEA) business tariff announcement in effect from the September 2026 billing month, exclusive of VAT.
| Line on the bill | Can rise with units unchanged when | What to look at on the two bills |
|---|---|---|
| Ft charge | The two months being compared fall in different periods | The Ft item on each month's bill |
| Demand charge | The month's highest short-interval load is higher | The kilowatts billed |
| Minimum charge | A month that once spiked is still inside the look-back window | The highest kilowatts of the previous months |
| Power factor charge | Peak kilovars exceed the set share of peak kilowatts | The kvar billed |
| Customer category | Moved up to a category with a different price structure | The category name or rate on the bill |
| Time-of-use share (TOU) | More units shift into the On Peak period | Units split between On Peak and Off Peak |
Units unchanged — where on the bill can the total still rise?
A monthly bill is made up of the energy charge at the tariff rate, the Ft charge and VAT. Units control only part of the total; the remaining lines can change without units moving.
Think of the bill as a receipt with several lines added into one total. The line tied directly to units is the energy charge. The other lines are calculated from things that are not units — the kilowatts drawn at the highest short interval of the month, kilovars, or an Ft rate that changes by period. So when the units of two months are close but the totals are far apart, the cause has to be hiding in a line that is not tied to units.
Under the announcements of both PEA and the Metropolitan Electricity Authority (MEA), a monthly bill consists of the charge at the rate of the customer's category, plus the Ft charge, and then VAT is applied. The published rates exclude VAT; VAT is charged at the announced percentage on the base charge including Ft, so an increase in any one line is amplified once more before the net total (the price structure of each category is covered in What a factory pays per unit of electricity and why no two factories pay the same).
The sections below go line by line through how each one can rise while units stay the same, and which lines result from the factory's own operation versus which are set from outside.
Ft: one rate for the whole period, but the two months compared may fall in different periods
Ft is a fixed rate per unit charged every month as a separate item on the bill, and adjusted in cycles set by the Energy Regulatory Commission (ERC). With units unchanged, the Ft amount can still differ if the two months fall in different periods.
Ft is a per-unit multiplier added to the charge at the normal rate. Within the same period this figure is constant: same units, same Ft amount. But one period lasts only a few months (Jan–Apr · May–Aug · Sep–Dec), so the months you are comparing may fall in different periods, and this line can differ without the units moving at all.
The MEA tariff announcement states that the Ft charged is adjusted every 4 months and is set as a constant rate per unit of electricity used. PEA's own announcement says only that Ft is a component of the bill; the adjustment cycle is taken from ERC documents, which apply nationwide.
The simplest check is to look at the Ft item on the two bills and see whether the rate per unit is the same. If it is not, part of the increase comes from here — and this is a part the factory does not set itself, unlike the demand charge and time-of-use share discussed next.
- Ft period
- The span of time during which the Ft rate per unit is held constant before being adjusted again in the next cycle set by the ERC
Demand charge: one short interval with machines running together can push this line up
The demand charge is measured from the highest short-interval average of the month, not from total units. Machines running together harder for just one interval can raise this line even though the month's units are unchanged (only for tariff types that charge for demand).
Units (kWh) say how much electricity was used over the whole month, but the demand charge says how much was drawn at the same time at the heaviest moment. The two can go in different directions. A factory using the same units but bunching its machine runs into one interval will get a higher demand charge than a factory using the same units but staggering them.
This rule is measured from the factory's single meter, taking the highest average over 15 minutes in the billing month, not the month's total units. The MEA announcement words the definition as the highest average power over 15 minutes, below 30 kilowatts, connected through a single meter — the same definition used to split business sizes — and PEA writes a definition along the same lines. The kilowatts shown on the bill have been rounded under the utility's rules, which you can read more about in What the demand charge is and how it is calculated.
Suppose a factory normally alternates between running its air compressors and its chillers. This month a technician switched on both sets together to rush a job on a single afternoon. The month's units are no different from last month, but the interval when both ran together became the highest short-interval average of the month, so the demand line is higher than last month.
The base used for this line also differs by rate type. The normal rate and TOD use the month's highest value, while the TOU rate uses only the highest value within the On Peak period. This rule applies to types 3, 4 and 5 of both PEA and MEA. So when comparing two months' bills, check when the billed peak occurred: on TOU, if the peak shifted from night-time to daytime, this line can rise with units unchanged.
This is the line the factory has the most control over, because it comes directly from the factory's own operating pattern, unlike Ft, which is set from outside.
- Demand charge
- A charge based on the highest power the factory draws at the same time during one short interval of the month, measured in kilowatts, separate from the units used over the whole month
✗ The surge when a motor starts makes the demand charge spike
✓ The factory's single meter calculates demand from the highest average over 15 minutes in the billing month, not an instantaneous value, so a surge lasting a few seconds has little effect
Two lines that ride along with the demand charge: minimum charge and power factor
Customers charged for demand have two more lines that can rise or appear without units changing: the minimum charge, anchored to a month that once spiked within the look-back window, and the power factor charge, calculated from kilovars against peak kilowatts.
If the two months' demand charges are close and the totals still differ, move on to these two lines. Neither is calculated from units; both are calculated from figures that ride along with the demand charge.
- kvar (kilovar)
- The unit of reactive power that the meter records separately from kilowatts, compared as a share of peak kilowatts to calculate the power factor charge
Minimum charge: a month that once spiked haunts the bill for the whole window
In a month when demand has dropped, the bill may still not drop with it, because the minimum charge is anchored to the highest demand of a month that once spiked within the look-back window.
The minimum charge is the floor of the bill; the bill cannot go below it. The rule is that the month's minimum charge must not be lower than 70% of the highest demand charge in the past 12 months, counting up to the current month. Put simply, the month in which you drew the most power at once is remembered and becomes the floor for the following months throughout that window.
PEA applies this rule to types 3, 4 and 5 and to some rates of types 6 and 7; MEA applies it to the rates of types 3, 4 and 5.
Suppose a factory had one month of rushed production in which demand spiked unusually high, then returned to its normal operation. Units and demand fall, but the bill does not fall as much as expected, because the spike month is still inside the look-back window and still sets the floor. This line is therefore controlled indirectly, by not letting demand spike in any single month.
Power factor charge: look at the kilovar figure, not the units
The power factor charge is levied on customers charged for demand when peak kilovars exceed the set share of the month's peak kilowatts. This line can appear or grow without units changing.
Besides kilowatts, the meter also records reactive power in kilovars (kvar). The power factor charge is levied on customers charged for demand (PEA's wording), only for the Lagging case, when the month's peak kvar exceeds 61.97% of peak kW; only the excess is charged, at the announced rate per kilovar, before VAT.
The base used for comparison is the month's peak kW; even on the TOU rate it is not only the On Peak value. MEA has a power factor clause in its announcement for types 3, 4 and 5.
For a two-month comparison, what to look at is the kilovars billed, not the units. If this line appears in one month or the excess kilovars increase, the total can differ even though units and kilowatts are close to before.
Customer category changed, or time-of-use share changed
If all the lines above are close to before and the total still differs, check the last two things: whether the category name on the bill has changed, and, on the TOU rate, whether more units have moved into the On Peak period.
These two differ from the earlier lines in that it is not a single line's figure moving, but the whole price structure changing, or the price per unit applied to each portion of units no longer being the same.
Moved to another category: same units, but the rate table has a different name
A type 3 customer whose demand or three-month average units reach the threshold is moved into type 4, and once moved up, even if electricity use falls, the type 4 rate continues to apply — there is no way back down to type 3.
A type 3 customer who in any month has demand of 1,000 kW or more, or whose average electricity use over 3 months exceeds 250,000 kWh/month, counted per month, is moved into type 4 (for MEA, into rate 4.2; for PEA, the average is counted from the three preceding months). If a two-month comparison shows the category name or rate does not match, every line has been priced with a different structure even though units are the same. The differences between categories are covered in How tariff types 3, 4 and 5 differ.
The point to know before expanding load is that this move up does not reverse itself. PEA's announcement for type 4 states that in any month where demand does not reach 1,000 kilowatts or electricity use does not exceed 250,000 units per month, the charge is still calculated at that rate. That means a month in which use drops below the threshold is still billed at type 4; there is no return to type 3. MEA's announcement has no such clause, only a clause on moving down to type 2.
Type 2 customers have a similar mechanism: in any month where demand reaches the threshold they are moved up to a category that charges for demand, which you can read on in What a factory pays per unit of electricity and why no two factories pay the same.
Time-of-use share: total units unchanged, but shifted into On Peak
TOU customers pay different prices by time period. With total units unchanged, using more in the On Peak period, or a month with more working days, can push the bill up.
The TOU rate splits prices into an On Peak period from 09.00 to 22.00 on Monday to Friday, and an Off Peak period covering the night hours of Monday to Friday, all day on Saturday and Sunday, National Labour Day and regular public holidays. These time-period rules come from the ERC announcement and apply to both utilities.
Because the price per unit of the two periods is not the same, this month's total units can equal last month's and still cost a different amount — if some units moved from the night shift into the daytime, or if this month has more Monday-to-Friday days than last month so the On Peak share of units is higher. On top of that, the TOU demand charge uses only the On Peak peak, as described above, so moving heavy load into the daytime hits two lines at once.
The time-of-use share is another part the factory sets itself through its operating schedule. The hours and days counted as Off Peak are covered in detail in Which hours are TOU On-Peak and Off-Peak.