KW VS KWH – Solar Energy Simple Breakdown

In this quick learning guide, let’s break down KW VS KWH in simple English.

You probably have heard these two terms regularly tossed around, but not sure what they mean or which one to pay attention to when it comes to calculating your solar power requirement and cost.

So here is the simple breakdown:

Are KW and KWH The Same?

KW (Kilowatts) – Energy Demand

kWh (Kilowatt – Hour) – Energy Consumption

Kilowatts measures the usage of power at a given time, and Kilowatt Hour measures energy usage over a time period.

More usage = more cost

For Example:

Tom uses about 500 kWh a day, and Dan uses about 40 kWh a day. 500 kWh costs MORE MONEY than just 40 kWh.

How To Really Make Sense Of KW and KWH?

When designing a power system for your RV, home, or a large facility, the power size is determined by the previous year’s consumption. (generally, the electric bill will show you all the numbers)

Picture KW as the speed of the car, and KWH is how much power is used after a period of time.

For example:

1 KW light bulb running for 1 hour = 1 KWH

1 KW light bulb running for 30 mins (0.5 hour) = 0.5 KWH

5 KW device running for 3 hours = 15 KWH

Sizing Power Requirement

Based on the above explanation, now you should be able to figure out how much power you need.

For example:

The average American household uses up to 890 kWh per month, which means roughly 30 KWH per day.

890 KWH / 30 = 30 KWH per day

Assume 7 peak sun hours per day, which means 30 KWH / 7 = 4.3 KW

Assume you have the option to buy a solar panel rated for 300W per panel.

4.3 KW + 4.3 KW X 0.2 (Account for 20% energy loss in the real world) = 5.16 KW

5.16 KW = 5160 W

How many solar panels do you need for your home in this simple example?

Just take the amount of wattage you need and divide it by the rate of energy a single panel can reproduce.

5160 W / 300 W = 17 panels

If you want to learn more about calculating the numbers of solar panels required, please read more here

Ying Xu

Graduated from the University of Kansas with an Aerospace Engineering degree & served 4 years as an US Air Force officer. Experienced with basic survival skills, weapon system security,  technical disaster recovery, and system troubleshooting

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