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Solar on all U.S. roofs would supply 39 percent of power

Lucas Mearian | April 11, 2016
California alone could generate 74 percent of its electricity.

A federal study has revealed that if Americans installed solar panels on every roof, it would supply 39% of the total power used by the U.S.

Researchers from the National Renewable Energy Laboratory (NREL) used light detection and ranging (lidar) data, geographic information systems and photovoltaic (PV) generation modeling to calculate the suitability of rooftops for hosting solar panels in 128 cities nationwide, representing about 23% of U.S. buildings.

The total national potential of rooftop solar power is 1,118 gigawatts (billion watts or GW) of installed capacity and 1,432 terawatt-hours (trillion watt hours or TWh) of annual energy generation. That equates to 39% of total national electric-sector sales last year.

Solar power generation 
Source: National Renewable Energy Laboratory. Click on image to enlarge. 

Within the 128 cities studied, researchers found that 83% of small buildings have a suitable location for PV installation, but only 26% of the total rooftop area on those buildings is suitable for development. Even so, the potential for power generation is enormous.

The study revealed a significantly greater capacity for energy generation than a previous NREL estimate of 664GW of installed capacity and 800 TWh of annual energy generation, the report stated.

"This report is the culmination of a three-year research effort and represents a significant advancement in our understanding of the potential for rooftop PV to contribute to meeting U.S. electricity demand," said Robert Margolis, NREL senior energy analyst and co-author of the report.

An earlier federal report showed rooftop solar panel installations could cut utility profits by 15% or more over the next eight years based on current installation trends. The study predicted that rooftop solar panel installations will grow from 0.2% market penetration today to 10% by 2022.

Margolis noted NREL's research estimated the potential only from existing, suitable rooftops, and not the "immense potential of ground-mounted PV."

"This amount... could take a large burden off our reliance on fossil-fuel-based power, but obviously, it'd be a massive undertaking to fit out all that available roof space," Margolis wrote in the report.

Solar power generation rooftop  
Source: National Renewable Energy Laboratory. 
Click on image to enlarge.

California has the greatest potential to offset electricity use through rooftop PV. The Golden State could generate 74% of the electricity sold by its utilities in 2013.

New England states could generate more than 45% of their energy needs because they have a low per-capita electricity consumption that offsets their below-average solar resource.

Washington, with the lowest population-weighted solar resource in the continental United States, could still generate 27% of its needs through rooftop solar. Some states with below-average solar resources (such as Minnesota, Maine, New York, and South Dakota) have similar or even greater potential to offset total sales compared to states with higher-quality resources (such as Arizona and Texas), the study showed.

 

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