Kill A Watt Meter: Creating a Loads List for Off-Grid Solar

Customers often ask how to figure out how much solar power and batteries they need to do an off-grid solar system.

Kill A Watt Meter & Loads List

The first step to do is to create a loads list. We have a helpful load calculator tool on our site that you can use.

We’re here today to show you how to use a Kill A Watt meter to help you create that loads list. A Kill A Watt meter is a device that you would plug into the outlet and then you would plug the device that you’re trying to figure out how much power it uses into the Kill A Watt meter.

In our demo below, we show you how to use a Kill A Watt meter when you’ve got a device that uses a variable amount to power. Any device or appliance that you use in your house is going to be UL Listed. It will have a label on the back that shows you how many watts or how many volts and amps and, from that, you can calculate volts x amps = watts. So, you can tell from the label how much power it’s rated to use.

However, that label isn’t always accurate or it’s not always the same. For instance, a refrigerator will be turning on and off throughout the day, depending on if the fridge is cold enough. So, if you were to just say “alright, it’s rated a certain wattage, simply multiply that by 24 hours,” you would have probably doubled the amount of power that you actually are using.

Using a device like a Kill A Watt meter will help you get an accurate reading how many watt hours, or kilowatt hours, does this actually use in a day. From that, you can calculate out your off-grid solar system.

About Author

Amy Beaudet
Amy Beaudet has been in the solar industry at the altE Store since 2007. She’s been a sales rep, an instructor, and an all around solar evangelist, sharing her passion for solar around the world. When not at work, she’s either sailing or skiing, depending on the season, but odds are good she’s still talking about solar on the boat or on the slopes. See more of Amy Beaudet's blog posts.


  1. Daniel-Southern California

    I have lived off-grid for nearly ten years now with solar and wind (full time-not a weekend/weekly warrior). Over supply of electrical self generation/storage is always prudent. Nothing more annoying or expensive than a back up generator running due to uncooperative weather or fridge/heater fan/fans running flat out 24/7.

    If you can afford it, double your estimated use in generation and storage. Panels/turbines eventually pay for themselves. Batteries NEVER do…ever..and the more deep discharge cycles a battery does, the sooner they wear out.

    Another suggestion: backup/redundant systems just in case of equipment/battery failure.

  2. Dave Y.

    Great video, thanks! This may seem pretty basic for some folks but is actually a very critical first step for determining how much solar to install for your needs. I really appreciate that you included the formulas too as the conversions are rarely spelled out clearly. You keep coming up with good topics 🙂

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