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How many solar panels would you need to power the USA?

3 min read

As solar becomes more of a standard way to generate electricity, the question of just how many solar panels we would need to power the entire U.S. is rising in our minds. Will every home need solar panels on their roof to generate enough power for the nation? Will we need massive solar farms stretching across large chunks of land around the country?

This is something we’ve all been speculating about for a bit now, and there’s great news about what it would look like to generate the necessary electricity for the United States. All we need to do is crunch a few numbers and it’s easy to see that it’s not only possible, but also very likely.

How many solar panels would you need to power the USA?

A good place to start is by looking at a report from the National Renewable Energy Laboratory (NREL): Land Use Requirements for Solar Power Plants in the United States. In this report, NREL states that about 3.4 acres of solar panels are required to generate one gigawatt hour of electricity over the course of one year.

The U.S. requires about 4 petawatts of electricity over one year to run life as normal. To put this into context, 1 petawatt equals about 1 billion million watts.

With the conservative numbers from NREL’s land use report, we can estimate that roughly 14,000,000 acres or 22,000 square miles of solar panel-filled land would be required to generate enough electricity to solar-power the U.S. This is about the size of the Mojave desert.

The exact number of panels used to fill this land mass could vary depending on panel size, the layout of the solar sites, and other equipment such as solar trackers on big utility solar sites. But knowing the land mass required is a good way of gauging the resources required, which is really what’s in question.

Is that the final number for miles of solar?

There are a couple of things that reduce these numbers a bit. For one thing, the NREL report on land usage is conservative in that solar panel efficiency has improved since the report was published.

Those numbers were based on 13 to 14 percent efficiency for solar modules. Now, in 2019, just six years later, solar panels on average have efficiency numbers between 15 to 18 percent. In fact, many solar panels are now available at 20 percent efficiency for commercial or utility solar sites.

This alone will reduce the number of solar panels needed and the required land mass to host those solar panels.

Secondly, the entire power load won’t depend entirely on big solar farms. Homeowners installing their own solar panels on rooftops could make up to about 34 percent of this electricity need.

With these things in mind, we can adjust our estimate from 22,000 square miles to just about 10,000 square miles. This is the number Elon Musk talked about at the National Governors Association meeting, referring to the space needed as taking up “a fairly small corner of Nevada or Texas or Utah.”

While having our nation powered by solar might not be as neat and tidy as that, it’s great to know that it’s absolutely possible to reach that renewable energy goal one day, especially with the advent of solar backup batteries to take care of the intermittency of solar.

Learn more about solar batteries through Vivint Solar here.

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