Your electric bill is based on your electricity usage, which fluctuates from month to month depending on the number of items in your home that use electricity, the efficiency of these items, and how much they are used.
Residential customers are billed based on kilowatt-hour (kWh) usage. A kilowatt-hour is the measure of electrical energy equivalent to a power consumption of 1,000 watts for one hour. Residential electricity usage tends to increase in the winter due to home heating needs, as well as in the summer due to the use of air conditioning, pool pumps, etc. Simple things like having a house guest, adding a new appliance or using one more frequently, or the use of holiday lights all impact electrical usage.
Commercial/Industrial customers are billed based on their kilowatt-hour usage as well as their demand, which is measured in kilowatts (kW). Demand is the highest quantity of kilowatts registered by the meter in any 15-minute interval during the billing cycle, but not less than eighty percent of the maximum demand established during the preceding summer season (June through September) or sixty percent of the maximum demand established during the winter season (October through May). The demand charge on a commercial bill may be identical several months in a row.