By  Jameson Dow 
31 August, 2023

Why putting solar panels beside highways is a no-brainer

California could generate enough electricity to power 270,000 homes by putting solar panels in the empty land next to highway interchanges in just 3 Southern California counties, according to a new report released today by Environment California and The Ray.

There is a lot of “dead” space between highways, which is currently not used for much of anything. It’s not a usable space for wildlife, either, due to the proximity of so many cars.

But what it does get is a lot of sun, especially in Southern California, where there are a lot of highways and a lot of sun.

The report highlights the benefits of using this empty land beside highways for electricity generation and totals up the potential energy available from all suitable areas in the counties of Los Angeles, San Diego, and Ventura.

And there is a lot of potential space combined across these three counties. Every highway interchange and every offramp will generally have some space for an installation like this. Here are some maps of potential sites examined by the report:

Put together, it’s a total of almost a gigawatt of potential solar power just from empty land.

Better yet, these locations are often near transmission lines and are already owned by the state, which makes developing the space for large solar projects easier than contracting or leasing with several property owners for land, building transmission lines to virgin desert areas, and so on.

Here’s an example of just one highway interchange in San Diego next to State Route 163:

This installation would have 1.86 MW of capacity, enough to power 180 homes. And that’s just one interchange, with many more that are ripe for these opportunities.

While the analysis covered just three counties, those counties are rather sprawling and populated with many people and highways, meaning there are plenty of highway interchanges covered by the report’s area.

But other counties with plenty of sun and plenty of highways, like Orange, San Bernardino, and Santa Clara, were not covered. Nor were the rest of California’s 58 counties. So, if the state were to find opportunities in every county, there would be far more free energy available.

There is currently a bill working its way through California’s legislature, known as SB49, introduced by Senator Josh Becker, who represents San Mateo and Santa Clara counties. Environment California has a page where Californians can contact their representatives and ask them to support the bill.

This isn’t just a no-brainer for California (as even Caltrans acknowledges) but for other states as well. In 2021, the Federal Highway Administration suggested that states do this very thing, and the Biden administration considers it a “game-changer” for meeting net-zero goals.

The Ray has a tool for mapping similar beside-highway solar opportunities across the country. Some states have already started putting solar panels beside highways, with installations existing in Georgia, Oregon, Maine, and others.

This is just one of the areas in which Environment California has advocated for solar panels. Another analysis shows that 5 million homes could be powered by putting solar on the roofs of warehouses in the state (and surely the warehouses themselves as well), allowing us to turn unproductive flat roofspace into a useful energy generation opportunity without having to clear additional land for solar farms. Add in parking lots and superstores, and aqueducts as California is currently piloting, and you could make a pretty big dent in emissions from electricity generation without a whole lot of effort.