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 was in the solar industry at the altE Store from 2007 until her untimely passing in 2021. She was a sales rep, instructor, and an all-around solar evangelist, sharing her passion for solar around the world. When whe wasn't at work, she enjoyed sailing and skiing - but odds were good she was 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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