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Estimating Electricity Costs of Residential Grows

November 26, 2019

  • Overview of Residential Electricity
  • Cost To Produce
  • Determining Electrical Rates
    • kilowatt-hours
    • power rating
    • convert watts to kilowatts
  • How To Calculate Electrical Costs
    • online calculators

Electricity distribution in homes

Electrical distribution to homes from electric service companies (4). Image from Technical Learning College. Image edited by RMK.

Overview of Residential Electricity

Power lines enter most homes overhead or underground to their electric meter and service entrance panel (3). An electric meter is monitored by your electric utility company to determine how many kilowatt-hours are consumed over a set period of time. Power utility companies will then base their billing upon the number of kilowatt-hours (KWh) consumed by a home. The main panel is usually right next to or under the meter. This is the central distribution point for the electrical circuits that run in your home. Subpanels inside a home usually exist and are connected to the main panel. These provide power to areas that have a number of different branch circuits for large appliances, such as the kitchen and laundry room. They also are equipped with a secondary set of circuit breakers. Wires from the main service panel enter the house where one hot wire and one neutral wire power conventional 120-volt lights and appliances through common outlets. Both hot wires and the neutral wire make a 240-volt circuit for large appliances such as air conditioners and dryers which have their own outlets throughout your home.

Types of sheathed wire

Types of sheathed wire image from the Basic Electricity 2018 book authored by Technical Learning College (4). Image from Technical Learning College.

A 120-volt outlet is extremely common and would be immediately recognizable by any individual. This is the outlet you use to plug in many different types of electronics including lamps, vacuum cleaners, television sets, and phone charging cables. A 240 volt outlet, on the other hand, is larger than the 120-volt outlet, with room for three individual prongs or plugs (or in some cases, four plugs) that come in various shapes and sizes. A number of appliances require more than 120 volts to run adequately. Your washing machine, dryer, and oven are the most common examples of residential appliances that require more than 120 volts to operate. All of them will technically run on 120-volts, but they will only be operating at about a quarter of full power making the device ineffective.

120volt outlet

120 volt outlets commonly seen in residences (4). Image from Technical Learning College.

Cost To Produce

Whether you are growing professionally in a commercial facility or growing at home as a hobby, it is important to know the costs to produce a pound (or you can think in ounces) of cannabis, especially in states where cannabis has been legalized and can be readily purchased at a licensed dispensary. Not everyone will have access to a quality dispensary, but the costs are still worth considering. If you are growing cannabis and the costs to produce are expensive, it may very well be possible to reduce costs to produce cannabis at home by understanding how much money is being spent on nutrients, equipment, and electricity.

Determining Electrical Rates

In order to estimate electrical costs for equipment use, you need to know what price you pay per kilowatt-hour (kWh) of electricity, the wattage of the grow equipment, the number of hours it’s in use on a daily basis, and some math. You can easily create a breakdown of electricity use for your entire grow or for each individual piece of equipment to make a determination on the effectiveness of the piece of grow equipment for your grow.

Note: Calculating electrical costs for equipment use is an estimation. The figure you come up with may differ slightly than the actual usage due to efficiency.

Kilowatt-hours are the standard that electrical companies use to determine how much power was used over a period of time rated in hours. You can easily find out how much you pay for a kilowatt-hour by reading your electric bill. For residents in Denver, Colorado and other parts of Colorado, Xcel Energy is the premier electric delivery company available. Based off my residence, the price rates I paid for service (kilo-watt hours) in the year of 2018 include:

  • Non-summer & Summer Tier 1 $0.055/KWh
  • Summer Tier 2 $0.099/KWh

If you are having difficulty finding what rates you pay, you can find your rate by looking under the electrical rates and breakdown on the back of your electric bill. The breakdown will include the kilowatt-hour rate and how many kilowatts were used by your residence to determine the total cost for your monthly bill.

Power Rating

The power rating is the wattage of a device. Determining the wattage of a piece of grow equipment is simple. Just read the back of the device or scan over the owner’s manual. If you do not have an owner’s manual, you can try to find the equipment specification online. Looking at the back or bottom of the device you may find a small metal plate or engraving on the device which will have all sorts of information, but the wattage is what is important here and it is represented as a number followed by the letter W such as “100W”.

Power rating of device

Power rating listed in watts on the bottom of an air pump device. Image by RMK.
Converting watts to kilowatts

You can convert watts to kilowatts by dividing the number of watts by 1000 (1 Kilowatt = 1,000 watts). This means that 100W = 0.10KWh

How To Calculate Electrical Costs

Calculating an estimation of electrical costs is easy. We will use the following equations below to get an estimation using the cost of electricity in kilowatt-hours, power rating of equipment, and duration that the equipment is powered on.

Electricity Consumed = Power Rating (95W) x Duration of Use (12 hours/day) = 1,140 watts/day

Electricity Consumed Conversion (Watts to Kilowatts) = 1,140W / 1000 = 1.14KWh

Electricity Price = kilowatt-hour rate fee ($0.055/KWh) x Electricity Consumed (1.14KWh) = $0.06/day

Electricity Price = $0.06/day for a 95W device used 12 hours/day.

Price per week = $0.06/day x 7 days = $0.44/week

Price per month = $0.06/day x 31 days = $1.91/month .25 days (to include leap years) = $22.90/year

Online Calculators

In addition to being able to estimate electricity costs by hand, you can also use an online calculator to determine approximately how much it costs to run an electrical device over a period of time. Online calculators such as Inch Calculator or Omni Electricity Cost Calculator are great online calculators used to estimate electricity costs.

Grow Equipment Power Rating Run Time KWh Conversion Daily Power Consumption Cost To Operate
HLG V2 100 LED Light 100W (95W) 12hrs 100 ÷ 1000= 0.10KWh 0.10KWh x 12hrs = 1.2KWh 1.2KWh x $0.055 = $0.07/day
Vortex Powerfan, VTX400, 4in. (2) 92W 24hrs 92 ÷ 1000= 0.092KWh 0.092KWh x 24hrs = 2.208KWh 2.208KWh x $0.055 = $0.12/day x 2 = $0.24/day
Eco Plus Air 1Plus Pump 3W 24hrs 3 ÷ 1000= 0.003KWh 0.003KWh x 24hrs = 0.072KWh 0.072KWh x $0.055 = $0.01/day
Total Electrical Costs $0.32/day $0.32/day x 7 = $2.24/week $0.32/day x 31 = $9.92/month $0.32/day x 365.25 = $116.88/year


  1. (2019). “Who We Are”. Xcel Energy.

  2. (n.d.). “4 inch Vortex Inline Fan - VTX400”. Vortex Powerfan. Oxygen Pot Systems.

  3. Gerrity, Sarah. (2014). “Infographic: Understanding The Grid”. United States Department of Energy.

  4. (2018). “Basic Electricity”. Technical Learning College.

  5. (2019). “How to Calculate Your Electric Bill”. Direct Energy.

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