What Is a Kilowatt-Hour?

You might hear the term “kilowatt-hour” occasionally in daily life, although it’s more likely in specific situations.

For instance, you might see the term on light bulbs, cooking appliances and other household items. But you’ll certainly see it on your solar powered equipment — specifically on its meters.

If you’re a solar user, it’s important to know what a kilowatt-hour (kWh) is. That knowledge helps you understand how much energy your panels generate and how much energy you consume, which hopefully will help you lead a more energy-responsible life.

Put simply, a kilowatt (KW) is the main unit we use to measure electrical energy. The root word, “Kilo” means “thousand” — so KW is 1,000 times greater than a single watt.

So, what is a kilowatt-hour in concrete terms? Because we know 1 KW is 1,000 times bigger than 1 W, we can now compare 1 KW to 1 kWh. One kWh equals 1 KW of power in one hour’s time. In SI units, 1 kWh equals 3.6 megajoules.

So, in other words, we can measure the KW of energy that a device produces or consumes within one hour’s time using the kWh.

When billing electrical energy, we most commonly use kilowatt-hour. So when reading your solar electric bill from your utility, you can expect to see the abbreviation “kWh.” Plus, utilities sometimes use metric prefixes for watt-hour (Wh) multiples and submultiples.

But how do KW and kWh apply to various appliances and items in (and on) your household, such as a solar panel system?

As far as a solar company is concerned, the nameplate value representing a solar system’s size is in KW. For example, a 6-KW solar panel system could have 20 solar modules, each at 300 KW. You’d divide 300 KW by the number of modules (20) and end up with 6 KW.

In theory, your 6-KW solar system should produce 6 KW of solar power at any given moment (with enough sun exposure, of course).

If you’re ready to join the green energy revolution, contact Sunwatt Energy Kenya for your solar system installation. Call/WhatsApp: +254705102000