Figuring Solar System Size and Square Footage

One of the first things to do once you’ve made the decision to go solar is figure out the answer to one question: How much solar do you need?
The answer to that question is based on a couple of key factors:

  • How many square feet does your residence allow for solar panels?
  • How much energy do you use?

After you determine these factors, there will be a few additional things to take into consideration. But more on that later. For now, let’s talk square footage.

How Many Square Feet Does Your Residence Allow for Solar Panels?

While it may seem intimidating to figure out your mountable square footage, there are some tools you can use to create an estimate.
Google’s Project Sunroof uses its satellite imagery to create a 3D model of your roof and account for nearby trees as it estimates the amount of available space solar panels could occupy on your roof. Simply type your address and let Google do the work!
Keep in mind, Project Sunroof can only provide an estimate and may not account for some obstacles on your roof that could impede the mounting of solar panels. If you want a more accurate assessment — and if you want to get a feel for what it will be like to mount the panels yourself — consider getting out on the roof and taking measurements of available space.
Don’t discount the option of a ground-mounted solar system if roof space is tight. Even if you have enough roof space, ground-mounted panels can be a great option on any property with a unused space that doesn’t get blocked by shadows from trees or structures. The amount of land space you need will vary by system size, but ideally should be unobstructed to the south, east and west.
Once you have a rough idea of available square footage, keep that number in your pocket and pull out your electric bill.

How Much Energy Do You Use?

This part is pretty easy if you can read your utility bill. Just look for the part that shows how many kilowatt hours (kWh) you consume per month. It’s a good idea to get 12 months of bills and average them out for seasonal fluctuations.
Once you have this information, the easiest way to match up your energy use with square footage is to use our DIY solar calculator where you can enter your average power consumption along with your location information to view a number of different system options with square footage for each.

You can even start viewing some of the available systems and prices.
If you don’t have enough square footage for your proposed system, you may have to reduce the amount of energy produced by your solar system.
Next we’ll talk about system design and preparing for installation.