Is It Wise To Install Solar Carports in Parking Lots?

In the United States, approximately 51% of utility-scale solar facilities are located in the desert; 33% are on farmland; and 10% are in grasslands and forests. Only 2.5% of solar energy in the United States comes from urban areas.

The reason for this seems compelling: it is cheaper to build on undeveloped land than on a roof or parking lot. In the race to replace fossil fuels and avoid catastrophic climate change, it is crucial to build alternative energy sources quickly and cheaply. It is also easier to manage several large solar farms in an open landscape than a thousand small solar farms scattered in urban areas.

Despite the green image, placing solar facilities on undeveloped land is usually not much better than placing subdivisions there. Rebecca Hernandez, an ecologist at the University of California, Davis, said that developers tend to flatten the site and “remove all vegetation on the ground.” This is bad for insects and the birds that feed on them. In the Southwest Desert, where most solar farms in the United States are now built, losses may include "1000-year-old creosote bushes and 100-year-old yucca", or even worse. For example, the proposed 530 MW Aratina solar project near Bollen, California will destroy nearly 4,300 western Joshua trees, which ironically are at risk due to development and climate change. (Currently considering obtaining national protection status.) In California, the endangered desert tortoise was eventually moved, Hernandez said, the result is unknown. And the trend of gathering solar energy facilities in the buffer zone around the reserve may confuse birds and other wildlife and complicate migration corridors.

In contrast, the attraction of parking lots and rooftops is that they are rich in resources, close to customers, mostly undeveloped for solar power generation, and are located on land that has been deprived of most of the biological value.

For example, a typical Wal-Mart Supercenter has a 5-acre parking lot, which is a wasteland, especially when you have to sweat under the bubbling asphalt of the sun. However, according to a recent study, with a canopy on it, it can support a 3 MW solar array. In addition to powering stores, neighboring communities, or hidden cars underneath, the canopy can also provide shade for customers — and allow them to shop longer because their car batteries are fully charged. If Wal-Mart did this in all of its 3,571 U.S. super centers, the total capacity would be 11.1 gigawatts of solar power-roughly equivalent to a dozen large coal-fired power plants. Considering the part-time nature of solar energy, Pierce believes this is enough to permanently shut down four of the power plants.

One reason such facilities are still scarce is that the cost of building solar energy on developed land is two to five times that of open space. Pearce said that for parking lot roofs, “you are looking for stronger structural steel with a fairly solid concrete foundation.” This is like building a building without walls. For listed companies that focus on quarterly performance, the payback period of 10 or 12 years also seems to be frustrating. But this is the wrong way to look at it, Pearce said. "If I can provide you with a return of more than 4% on a guaranteed infrastructure investment that lasts for at least 25 years," this is a wise investment. It is also possible to completely avoid the upfront costs, and third-party companies or non-profit organizations pay for installation costs in accordance with the power purchase agreement.