SRP Demand Concepts

The Customer Generation Price Plan has the same on-peak hours as SRP's Time-of-Use (TOU) price plan, but is different in that it offers two ways to control your bill:

  • The energy charge on this plan is about half the rate of the TOU plan. It's also the lowest of any SRP residential price plan. Energy is the amount of power you consume over time.
  • There is a per-kilowatt demand charge, based upon your usage of the energy supplied by SRP. Demand is the amount of power your home needs at any given point in time. By limiting simultaneous use of appliances during on-peak hours, you can keep the demand charge lower. Your solar generation may help to offset some of your demand for energy from SRP during some on-peak hours, but because solar production can be affected by external conditions such as clouds, relying on it to lower your demand may be risky. Read more
    The demand charge for each billing cycle is calculated per kilowatt (kW). It is based on the 30-minute interval during on-peak hours when your home used the maximum or peak amount of electricity. These intervals are measured between the hour and half-hour during on-peak hours (for example, between 1 and 1:30 p.m. and 1:30 p.m. and 2 p.m., etc.)On-peak hours are weekdays 5–9 a.m. and 5–9 p.m. from November through April and weekdays from 1–8 p.m. May through September. All other times, including weekends and six holidays are off-peak and the demand charge does not apply.

The Customer Generation Price Plan is the price plan for residential customers who choose to produce some of their own electricity using rooftop solar or other means.

The best way to save money on this plan is to:

  • Shift energy use from on-peak to off-peak hours. On-peak hours are weekdays from 5-9 a.m. and 5-9 p.m. November through April and weekdays from 1-8 p.m. May through October. All other times, including weekends and six holidays,* are off-peak.
  • Manage energy use in your home so major appliances that demand large amounts of electricity don't run at the same time during on-peak hours.

The above chart reflects a temporary decrease to winter prices that took effect with the January 2017 billing cycle. Effective with the November 2017 billing cycle, the winter energy charge for the Customer Generation Price Plan will return to 3.9 cents per kilowatt hour off-peak and 4.3 cents during on-peak. Time-of-Use prices will return to 7.11 cents per kilowatt hour off-peak and 10.2 cents during on-peak. Please see the Customer Generation Price Plant sheet on SRP's website for complete details.

The monthly service charge, which helps cover the costs of grid access and maintenance, is $32.44 on this plan for most residential customer. It is $20 on TOU.

E-27 ("SRP Solar Plan")

Effective: April 2015 Billing Cycle Includes Temporary Reduction to the Environmental Programs Cost Adjustment Factor and the Fuel and Purchased Power Adjustment Mechanism



Availability of this E-27 P Pilot Price Plan will be solely determined by SRP, and is subject to equipment availability and other conditions, as determined in SRP’s sole discretion. No more than 5,000 customers may concurrently participate on this pilot price plan.


Service under this price plan is limited to residential customers without on-site generation. This plan is applicable to a single family house, a single unit in a multiple family house, a single unit in a multiple apartment, a manufactured housing unit, or other residential dwelling, supplied through one point of delivery and measured through one meter. Service under this price plan excludes resale, sub-metering and standby uses.


Equipment used to provide time-of-use service must be physically accessible to SRP personnel without prior notice.


Sixty hertz alternating current at approximately 120/240 volts, single-phase. SRP, in its sole discretion, may provide three-phase service, at not more than 120/240 volts.


A. On-peak hours from May 1 through October 31 consist of those hours from 1 p.m. to 8 p.m., Monday through Friday, Mountain Standard Time, excluding the holidays listed in Condition B below. On-peak hours from November 1 through April 30 consist of those hours from 5 a.m. to 9 a.m. and from 5 p.m. to 9 p.m., Monday through Friday, Mountain Standard Time, excluding the holidays listed in Condition B below. All other hours are off-peak.

B. The following holidays are off-peak: New Year’s Day (observed), Memorial Day (observed), Independence Day (observed), Labor Day, Thanksgiving Day and Christmas Day (observed).

C. Metering will be such that kilowatts (kW) and kilowatt-hours (kWh) can be related to time-of-use.

D. A customer may cancel service under this price plan and elect service under another applicable price plan. The customer may not subsequently elect service under this price plan for at least one year after the effective date of cancellation.

E. A customer requiring additional interconnection, metering, or other equipment beyond what is necessary for SRP to provide basic service applicable under this price plan must pay SRP for the costs of such additional equipment.

F. Applicable monthly charges or credits may be converted to daily amounts. The amounts would be annualized and then converted to daily charges or credits.

For more a more detailed SRP statement of rates please click on link below to download document:

What Is Demand vs. Consumption?

Understanding Demand and Consumption

Demand = KW (kilowatt)

Consumption = KWH (kilowatt hour)

The difference between demand (KW) and consumption (KWH) is vital to your choices in reducing your energy costs. A simple way to see the difference between demand and consumption is by considering two examples.

LIGHTING EXAMPLE: One 100-watt light bulb burning for 10 hours consumes 1,000 watt-hours or 1 kWh. The entire time it is on, it requires or "demands" 100 watts or 0.1 kW from the utility. That means the utility must have that 0.1 kW ready whenever the customer turns the lamp on.

Similarly, ten 100-watt light bulbs burning for 1 hour consume 1,000 watt-hours or 1 kWh. Note that in both examples, the consumption is 1 kWh, however, look how differently the second situation impacts the utility from a demand perspective. The serving utility must now be prepared to provide ten times as much 'capacity' in response to the "demand" of the 10 light bulbs operating all at once.

If both of these customers are billed for their consumption only, both will get the same bill for 1 kWh of energy. And that is the way most residential customers are billed. But the requirement for the utility to meet this energy requirement is very different. In the second case, the utility has to have 10 times more generating 'capacity' to provide the second customer's brief high demand for power compared to the first case.

Commercial and industrial customers are often billed for their hourly consumption patterns and their peak demand for energy. These customers often have special meters that measure both, unlike residential meters that just record total consumption in a time period, usually one month.

So, you might ask, "why doesn't the utility bill all customers for demand and consumption?" Seems like that is only fair. And it would be, but the fact is that most homes have a pretty similar demand profile and the meters capable of measuring both demand and consumption are much more expensive. Far too expensive to justify having one on every home. So all most residential customers need to be concerned with now is consumption billing. As the cost of metering drops, and as automatic metering advances, we may see increased use of demand billing for homes.

Analogies for Understanding Demand and Consumption


Another way of understanding demand and consumption is with a "filling the bucket" analogy.
Suppose you want to fill a 5 gallon bucket with water. You can use an inexpensive hose connection
to your sink providing 1 gallon per minute to do it, and it will take 5 minutes.

Or you can get to a more expensive large faucet that provides 5 gallons per minute, it will fill in just one minute.

The flow rate is the equivalent to demand, and the 5 gallons of water are equivalent to consumption.
In this example, filling both buckets has the same "consumption" but very different "demands."

The same is true of electricity. While you may be able to accomplish the same thing by operating a small wattage appliance for many hours as operating something of higher wattage for just a few, the higher wattage piece of equipment will create a higher demand on the utility. Using our analogy, you are asking
for a larger pipe, and that costs more. If time is of the essence, it might be worth having the more expensive high flow rate or wattage. This is why utilities often charge some customers for both demand and consumption. A customer that sets a high demand requires more services from the utility--additional generating plant capacity, and more expense in lines, transformers and substation equipment.

Some people like to use a automobile analogy to explain and understand how demand and consumption relate. The car's speedometer is like the demand meter and the odometer is like a consumption meter. Two cars could travel the same 100 mile road, one at 10 miles per hour for 10 hours and the other at 100 miles per hour for 1 hour. It takes a much more capable and expensive engine to power the car at 100 miles per hour than it does to power the one going only 10 miles per hour.

As you have just learned, electric power use is metered in two ways: on maximum kilowatt use during a given time period (i.e., kW demand typically measured in 15-minute or 30-minute intervals) and on total cumulative consumption in kilowatt hours (kWh). A customer's electric rate is set using a complex process
of tracking cost of services and often seeking regulatory approvals. The general theory is that demand charges reflect the utilities' fixed costs of providing a given level of power availability to the customer, and energy charges reflect the variable portion of those costs as the

customer actually uses that power availability.

Power companies often use a meter that records the power use during either a 15- or 30-minute time window. The average power used during that window is used to calculate the kW demand. The peak demand used for billing purposes in any month can be:

1. Time of Day: Dependent on the time of day (i.e., on-peak {usually during the day} and off-peak {usually at night time periods) and/or the day of the week (e.g., Monday through Friday and separately for weekends):
The metering system tracks the highest usage anytime during the month under the appropriate time windows. These pricing schedules are generally referred to as Time of Use (TOU) rates.

2. Seasonally Differentiated: For example, the demand charge might be higher during the summer than during the winter, or vice versa.

3. Declining Blocks: This is where the demand charge up to a given level is at one price with the price declining above that level. For example, the demand charge might be $10 per kW up to 10,000 kW demand, and drop to $6 per kW for demands in excess of 10,000 kW.

4. Interruptible Blocks: The demand charge depends upon whether the customer can reduce electrical demand to a given level if it is notified in advance by the utility. The price reduction often varies with the time of notice (i.e., the discount is higher if shorter notice is given). Some utilities also offer direct load control for air conditioning and water heating equipment, the utility itself can cycle this equipment on and off for brief periods.

5. Ratchet: Certain rate designs incorporate minimum billing demands based upon historical peak demands. For example, if the peak demand last summer was 500 kW and the rate design has a 50% ratchet, the minimum billing demand would be 250kW (500 kW times 50%) for the following eleven months, regardless of whether the actual demands were lower.

The meter recording kWh power use during either a 15- or 30-minute time window also tallies total kWh use. This meter is read at roughly monthly intervals and total power use is billed according to applicable pricing schedules. The type of energy charge pricing in common use includes:

1. Time of day: For example, on-peak and off-peak time periods and/or the day of the week (e.g., Monday through Friday):
These pricing schedules are generally referred to as Time of Use (TOU) rates.

2. Seasonally Differentiated: For example, the energy charge might be higher during the summer than during the winter, or vice versa.

3. Declining Blocks: This is typically where the energy charge to a given level is at one price and that price declines above that level. For example the energy charge might be $0.05 per kWh for the first 100,000 kWhrs used in a month and drop to $0.04 per kWh for the next 100,000 kWhrs.