In March 2016, the National Renewable Energy Laboratory (NREL) released a new report finding the technical potential of rooftop solar PV in the United States is 1,118 GW of installed capacity and 1,432 TWh of annual energy generation.

Key Details

• The purpose of the NREL analysis was to quantify the technical potential of solar PV systems on existing, suitable roofs within the continental United States
  • The analysis includes detailed assumptions concerning rooftop suitability, roof orientation, local solar resource, PV system performance assumptions, and building footprints
  • The results should be considered an upper bound on potential deployment as the analysis does not consider economic performance of PV systems
• The generation estimate (i.e., 1,432 TWh) equates to 39% of national electricity sales in 2013
• Technical potential as a percentage of state electricity sales is the greatest in California (74%), Maine (60%), Vermont (60%), Rhode Island (57%), and New Hampshire (53%)
• Small buildings (defined as a footprint smaller than 5,000 ft²) account for approximately 65% of the technical potential due to the sheer number of buildings
• The outcome is highly sensitive to module performance. Technical potential increases by roughly 25% when module efficiency increases from 16% (base assumption) to 20% (efficiency of current premium systems)
• The study does not consider integration issues but notes a significant quantity of rooftop PV would require a flexible grid, supporting infrastructure, and a suite of enabling technologies

Implications

Even though economic and market potential would be significantly lower, the new study provides stakeholders insight into the upper limits of rooftop solar penetrations. Further, the analysis and data could provide the foundation for more detailed state or utility specific analyses.
 
Additional Information

NREL: Rooftop Solar Photovoltaic Technical Potential in the United States: A Detailed Assessment

GTM: Nearly 40% of US Electricity Could Come From Rooftop Solar
 
This report is part of the Clean Tech & Sustainability Minute series. To view all featured Minutes, please click here.