Forty-four years later, parking lots are still seen as part of the problem with America’s transportation, energy, and design system. The entities that own and manage stores, schools, malls, and office buildings spent a lot of resources covering valuable open space in concrete and asphalt to accommodate shoppers, students, and workers – who have no other option but to drive themselves. When empty, parking lots look like a forlorn waste of space. When they’re full, they’re difficult and hazardous to negotiate. “We all use parking lots, and we all kind of hate them,” as Eran Ben Joseph, a professor of landscape architecture and urban design at the Massachusetts Institute of Technology, and author of the 2012 book Rethinking a Lot: The Design and Culture of Parking, put it. “Yet they’re part of everyday life and we have to deal with that.

A 2005 study by the Environmental Protection Administration estimated there were some 105.2 million parking spaces in the U.S. But according to Ben Joseph, that could be low. He told the New York Times that he estimated there were some 500 million parking spaces in the U.S., “occupying some 3,590 square miles, or an area larger than Delaware and Rhode Island combined.”

But increasingly, when it comes to energy use and sustainability, parking lots are actually becoming part of the solution. Why? In many parts of the country, they are becoming solar power plants.

Typically, solar panels are most easily placed in open fields, or on the roofs of building – flat surfaces that afford direct exposure to the sun and aren’t otherwise being used. The same principle applies to parking lots and garages – provided you build a bunch of canopies to serve as platforms for the solar panels.

Such canopies provide a bunch of benefits. In the summer and in hotter regions, they provide shade for parked cars, preventing them from getting too hot. At all times of the year, they provide protection from rain. In the winter, they can shield drivers from the annoyance of having to wipe snow and ice off their windshields. And when there’s light, they produce electricity.

Several companies are now scaling up to turn America’s parking lots into power plants. One of those active in the Northeast is Solaire Generation, based in New York City. “We see a unique opportunity to make a significant and enduring contribution to the global deployment of renewable energy through the parking lot,” as the company describes about on its website, Solaire has a meter tallying its progress: 2.9 million square feet and 23,100 parking spaces.

Solaire’s projects include a Whole Foods in Brooklyn, New York, where it supplies about 25 percent of the store’s electricity, a 3.8-megawatt installation at Dow Jones headquarters in suburban New Jersey. Covering about 230,000 square feet of lots, it produces about half the building’s electricity. Solaire has an even bigger project at nearby Rutgers University, where, in what it claims is the largest such installation in the U.S., it has covered 28 acres of parking lots with enough panels to generate up to 8 megawatts of electricity.

Solar canopies are popular in sunnier parts of the country. In Georgia, MARTA (the Metropolitan Atlantic Rapid Transit Authority) built a huge solar canopy at its bus depot in Decatur. And in California, where carports are already common, solar canopies have become a fixture. M Bar C Construction, based in San Marcos, California, has completed a series of large projects at universities, colleges, and school systems across California.

The next step toward greater sustainability would be to turn those solar canopies into fueling stations. And that is slowly happening. With each passing month, about 11,000 new all-electric or plug-in hybrid vehicles hit the road. California alone already has more than 100,000 plug-in vehicles. And in some parking lots, building owners are linking electric-vehicle charging stations to the canopies. Solaire has set up charging capabilities at a project it built at a yacht club in Massachusetts, for example.

In many areas, people get excited when the see that parking is free of charge. In a growing number of lots, drivers may be seeking out spots that come with a charge.