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Watts to kWh Calculator

If you’ve got a solar setup or are looking into setting one up, you might be interested in a watts to kWh calculator. 

This allows you to determine how many kilowatt hours of power are generated by your setup. This is information that you need when determining how much of your home your solar setup can power.

It’s important to not overpower your solar setup. The electricity generated from the sun’s light energy is stored in the batteries inside your inverter. 

When you power too many appliances inside your home, you can deplete these batteries, meaning you won’t be able to use as much power when the sun isn’t shining because you can’t store it effectively.

Ultimately, discharging batteries to a very low level reduces their lifespan. By using this formula, you can be aware of how much energy your solar setup is producing. You can then ensure you never use too much at once. This will protect your batteries and your pocket.

So, let’s get into it.

Convert Watts to kWh

convert watts to kwh

Converting watts to kilowatt-hours is as simple as using a formula. But first, we want to ensure you have an understanding of both units, which are used to measure power.

A Watt is a single unit of power. It’s the amount of energy an item needs to perform its job, and describes the rate at which energy is consumed.

This shouldn’t be confused with amps, which are used to measure current. We have a useful guide on converting watts to amps if that’s what you’re looking for.

Energy is defined as the capacity to do work, while power is defined as the rate at which work is done. The watt is the unit used to measure power, hence the definition “the rate at which energy is consumed.”

The symbol for watt is W, which you’ll see us using in the formula below. If you’re looking for a watt calculator, we have a guide on how to do that as well.

Kilowatts and Solar Panels

So how do watts fit into the solar panel picture? Well, since watts measure power, they will give you a quantification of the power produced by your solar panel. 

If your panel says it produces 250 W, that means it’s capable of producing 250 units of power when it’s in optimal conditions. This would be full exposure to sunlight at the brightest time of day.

A kilowatt-hour, on the other hand, refers to 1,000 watts being used in an hour. It’s important to remember that it’s a unit used to measure power usage, not time. This often confuses people. 

convert watt to kwh

Workable Example

Here’s an example that illustrates kilowatt-hours:

Say you have a lightbulb that uses 100 W of power per hour. If you leave that lightbulb on for 10 hours, you will have used one kilowatt-hour of energy. 

Calculating this can help you understand your electric bill. Have a look at our electric bill calculator for more information on that calculation.

Now that you understand the difference between watts and kilowatt-hours, let’s get into the formula you’ll need to use.

Watts to kWh Formula

In mathematical formulas, kilowatt-hours are represented using the letters kWh. Watts, as you know, are represented using the letter W.

The watts to kilowatt-hours formula is as follows:

kWh = (watts x hours) / 1000

To use that formula, you’ll need to know the wattage capability of your solar panels. You can find this in the user’s manual of your panel, as well as its packaging. If you’re unsure, feel free to contact us; we’re always happy to help make solar simple.

Knowing these values will help you when you start working on your solar generator watt calculator.

How Do I Do It?

kilowatt hour conversions

Let’s say you have a 250W solar panel. To make this example simple, we’ll assume that’s the entire capability of your solar panel setup.

If you have more than one panel, you can simply add the wattage of all the panels together, and use that when doing your calculation.

We’ll assume your panel gets 4 hours of bright sunlight for this equation. This means it’ll be producing its full potential when it comes to wattage. 

Your equation will look like this:

kWh = (watts x hours) / 1000

        = (250W x 4) / 1000

        = (1000) / 1000

        = 1 kWh.

Super simple. Fortunately, for this equation, you don’t need to know any external factors about your system, so you don’t need to worry about converting watts to volts.

You now know that your setup gives you one kilowatt-hour of energy. 

To bring that number to life for you, let’s assume you have an iron that uses 1,000 W of energy per hour. With one kWh of energy, you could power that iron for one hour.


If you’re looking to reduce your electric and gas bill, take a look at our solar-powered generators. Make use of all that free- renewable energy available to you to power your appliances.

Feel free to give us a call at (877) 340-1237 if you’re not sure about your solar needs.

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