  # What is the Difference Between a Kilowatt and Kilowatt Hour? Feb 15, 2021 0 Solar Topps 2 min read

A kilowatt (kW) is a power measurement that equals 1000 watts. A watt “is the International System of Units’ (SI) standard unit of power (energy per unit time), the equivalent of one joule per second” (https://whatis.techtarget.com/definition/watt). A joule is a unit of energy equal to 0.001 kilojoules. Sound too complicated? Okay, how about this. “Everything that plugs into the wall uses a certain amount of watts per hour. A cell phone charging, for example, takes about 2 – 6 watts. So if you have a 5-watt phone/phone charger and plug it in for a full hour, you’re using 5 watt-hours. You’d have to plug in 200 cell phones charging heavily for a full hour to use a kilowatt of power. That would equal 1-kilowatt hour.” A kilowatt-hour (kWh) is an energy measurement. So, the difference between kW and kWh is a kW is a power measurement, while a kWh is an energy measurement (https://decisiondata.org/solar/kilowatts-and-kilowatt-hours/).

When it comes to solar energy systems and explaining how they work, you’ll hear a lot of talk about kilowatt-hours of energy usage and the difference between regular electric bills and solar costs in relation to converting your system to solar. So what is it all about? Well, when calculating cost comparisons and figuring what size solar system your home requires, a solar professional or solar company needs to first assess what your regular energy usage is in order to estimate the number of solar panels you’ll need as part of your new solar system. The number of solar panels is based upon your average electricity usage, and that number provides data to estimate the cost of your system and your savings. Providing this data assists in calculating what your cost per kilowatt is and what it will be in the future.

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