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Watts Per Hour Calculator

If you’re new to the field of renewable energy, you may come across some terms you don’t understand.

One of these is watts per hour. But what does it mean, why do you need it, and how do you calculate it? Read on, and you’ll find out, in our watts per hour calculator guide.

Error: Enter a valid number of watts (W).
Error: Enter a valid number of hours.
watt hours (Wh)
Conversion formula: watt hours = watts × hours

What Are Watts and Why Do They Matter?

watt per hour

Watts are the unit of power. They measure the rate at which energy is transferred. The appliances in your home each use a certain amount of energy to function. This is expressed in watts. 

When you get your electricity bill, you’re paying for the total amount of watts used. As you can imagine, they add up quickly, and electricity bills are usually expressed in kilowatts. A kilowatt is equal to 1000 watts, hence the prefix kilo-, which means a thousand.

What Are Watts Per Hour? 

In electrical applications, as well as solar systems, you’ll come across the term watts per hour or watt-hours. But what are these? 

Watts per hour (or watt-hours) measures the use of power over an hour. 

Watts Per Hour Calculator

So what is the formula for calculating watts per hour? It’s very simple.  

Watts x Hours = Watt hours (Wh).

kilowatt per hour cost

Calculating Watt Hours

As an example of calculating watt hours:

A light bulb that uses 100 watts per hour, uses 100 watt-hours of energy per hour. In 2 hours, it will have used 200 watt-hours (200 Wh) of energy. 

Calculating Kilowatt Hours

An example of how to convert watts to kilowatts is as follows: 

In 24 hours, that same lightbulb would use 2,400watt hours of energy. But it’s over a thousand, so you need to convert watts to kilowatts.

Because a kilowatt is equal to a thousand watts, simply divide the 2,400 watts by 1,000. That translates to 2.4-kilowatt hours (2.4kWh).  

Why Do I Need to Know This?

Once you understand the watts per hour calculator method, you can figure out what your power bill will be. You’ll also be able to better understand it when it arrives. 

Remember, for residential or commercial power consumption, the watt-to-kilowatt-hour calculator is used to convert watts to kWh.

How Does This Apply to Solar Panels?

When you invest in one of our home solar panel kits, you’ll need basic electrical know-how. Things like how to calculate watts per hour, and how to convert watts to volts. This helps you to select and install the right ones for your needs.

Generally, the larger the solar panel is, the more power it will be able to generate. What you need for your home or office will be far greater than what you need for your RV.

Why would you need a watt-hour calculator when deciding on the right solar setup for your needs? Solar panels offer different power outputs, and most solar panels rated for residential use generate between 250 and 400 watts per hour. 

The amount of power that you need for your home will also dictate the number of panels you install. You can use the watt calculator for home but remember that residential use will be high enough to be expressed in kilowatts.

What About Solar Batteries?

The sun’s energy can only be collected when the sun is out. But solar batteries can store the solar power produced by your solar panels during the day. 

So, do you need to use this calculator for solar batteries? No. Because most solar batteries show their capacity in Amp-hours instead of Watt-hours, you would need to convert watts to amps


Harnessing the power of the sun to power up your home or RV is not only sustainable and cost-effective, but it can also be fun. But that’s only when you know how to go about it. 

Fortunately, solar can be simple. And we make it even simpler with the best range of solar panels, batteries, and generators. Contact us for advice about the right setup for your needs.

You can find all of the solar & electrical calculators we have created in order to help you plan, size and install your own solar power system here.

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