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What’s Watts? Electricity Measurement Explained

We talk about solar energy and use the term “watts” in many different ways. While most Americans understand megawatts are bigger than watts, what else do you know about the differences? We can clear things up a bit for you.


The basic unit of electrical power that measures electricity use at a specific moment is the watt (W). Measured in watts, light bulbs indicate the amount of energy used when the light fixture they’re in is turned on. For example, a 30-watt (30W) light bulb uses 30 watts of electricity when it’s turned on. Turning on a lamp with a 30-watt bulb for one hour uses 30 watt-hours (Wh) of electricity. (Here’s a bit of trivia: Since the Watt was named after Scottish inventor and engineer James Watt, abbreviations for watt always use a capital W.)


Large appliances use energy that’s measured in kilowatts (kW). One kilowatt equals 1,000 watts. Most home solar panels produce clean, renewable energy that’s measured in kilowatts. Your electricity bill measures your electrical usage over the month, and it’s measured in kilowatt-hours (kWh). One kWh is equal to using 1,000 watts for one hour. Using energy efficient appliances and unplugging electronics and appliances not in use can reduce your electrical usage over time – and installing solar panels that generate electricity to reduce your use of your utility’s grid can reduce your electricity bill.


A large solar field or the cumulative total of solar installations may be measured in megawatts (MW). This is equal to 1,000 kilowatts – or 1 million watts. At Nelnet Renewable Energy, we design, install, and maintain solar systems for cities, farms, schools, water facilities, manufacturers, businesses, utilities, and health systems. Many of these large solar systems produce clean solar electricity that’s measured in megawatts. Over time, these large solar projects produce many megawatt-hours (MWh) of clean energy – shrinking carbon footprints and making our environment healthier.


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