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What is a Kilowatt Hour (kWh)?

  A kilowatt hour (kWh) measures the use of electric energy. One kWh is equal to 1,000 watts of power—or 1 kW—used over a period of one hour. Growers calculate the kilowatt hours of their lighting system to determine the overall energy consumption of their grow lights. This gives a clue as to the efficiency of the lamps and the potential energy costs.  

How Do You Calculate Kilowatt Hours?

  The formula for calculating kWh is very simple. You simply multiply the total kW of energy your lights consume by the total number of hours those lights will be in operation.    For example, if you have 4 grow lights that each consume 500 watts, your lighting system consumes a total of 2,000 watts or 2 kW. If all four of those lights will be in operation for 12 hours a day, you would calculate your daily energy consumption as:   2 kW x 12 hours = 24 kWh