According to some estimates, the United States has two billion parking spots. The average parking spot is about 18 feet long and eight feet wide, for a total of 144 square feet. A 480 watt QCells Q.PEAK DUO XL-G10.2 is approximately 24.8 square feet. So, we can fit nearly six modules in a parking spot, with a capacity of 2,880 watts.
If we were to cover just 25% of the country’s parking spots with 2.88 kWdc per spot, the capacity of those 500 million parking spots would total 1.44 TW. And if we assume a lower average generation capacity factor due to suboptimal angling of the panels – let’s assume 15% – they would generate 1.89 PWh of electricity. The total electrical consumption of the US is currently around 4 PWh per year.
Image: Michigan State University
California Senator Josh Becker (D-San Mateo) submitted a new piece of legislation with a goal to motivate solar carport installations in California via a tax incentive. The bill, SB 49, is light in its initial wording:
SECTION 1. It is the intent of the Legislature to enact legislation to provide tax incentives for the construction of solar canopies over large parking lots to boost the local generation of clean electricity in urban and suburban areas while reducing the need for dedicated land in rural areas and transmission to deliver the clean energy into population centers.
The bill will be up for debate in early 2023.
Senator Becker’s press release notes that, “pavement makes up 35%-50% of the total surface area in cities, and 40% of that pavement is parking lots.” It also cites California-specific solar carport figures.
For example, Los Angeles County has 101 square miles of parking lots, and about 25% of the state’s population. The press release extrapolates these numbers by population, inferring that there should be approximately 400 square miles of parking lots in the state, equivalent to 26 GW of solar canopies.
Image: Solar Carports LLC
An analysis by Yale University suggests that carports in the state could meet about one-third of the state’s electricity demand.
The Senator also notes that California’s energy agencies estimate that the state needs about 110 GW of new solar power to meet its 100% clean energy target by 2045.
Some states have already put in place incentives for solar carports, offsetting the additional costs of steel, installation and grid connection. These additional costs would normally add as much as $1 per watt versus the price of a typical commercial rooftop installation.
Image: Albuquerque Bernalillo County Water Utility Authority
Massachusetts’ SMART program offers a 6¢/kWh incentive for twenty years for any “Canopy Solar Tariff Generation Unit”. Rhode Island’s RE Growth program offers a twenty year, 5¢/kWh incentive for solar carports, though it looks like this incentive was not renewed for 2023.
France recently passed a law that makes solar carports mandatory for all parking lots greater than 1,500 square meters.
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Why not follow the French model and require parking facilities for >80 cars to be at least 50% covered by solar panels by 2028? Note the article says France requires car parks greater than 1500 m2 which is in fact incorrect the law is based around the numbers of parking spaces (>80) with an earlier compliance date for >400 spaces