Dramatic improvements to solar technologies and other clean energy technologies have enabled recent rapid growth in deployment and are providing cost-effective options for decarbonizing the U.S. electric grid. The Solar Futures Study explores the role of solar in decarbonizing the grid. Through state-of-the-art modeling, the study envisions deep grid decarbonization by 2035, as driven by a required emissions-reduction target. It also explores how electrification could enable a low-carbon grid to extend decarbonization to the broader energy system (the electric grid plus all direct fuel use in buildings, transportation, and industry) through 2050. 

The Solar Futures Study uses a suite of detailed power-sector models to develop and evaluate three core scenarios. The “Reference” scenario outlines a business-as-usual future, which includes existing state and federal clean energy policies but lacks a comprehensive effort to decarbonize the grid. The “Decarbonization (Decarb)” scenario assumes policies drive a 95% reduction (from 2005 levels) in the grid’s carbon dioxide emissions by 2035 and a 100% reduction by 2050. This scenario assumes more aggressive cost-reduction projections than the Reference scenario for solar as well as other renewable and energy storage technologies, but it uses standard future projections for electricity demand. The “Decarbonization with Electrification (Decarb+E)” scenario goes further by including large-scale electrification of end uses. The study also analyzes the potential for solar to contribute to a future with more complete decarbonization of the U.S. energy system by 2050, although this analysis is simplified in comparison to the grid-decarbonization analysis and thus entails greater uncertainty. 

Even under the Reference scenario, installed solar capacity increases by nearly a factor of 7 by 2050, and grid emissions decline by 45% by 2035 and 61% by 2050, relative to 2005 levels. That is, even without a concerted policy effort, market forces and technology advances will drive significant deployment of solar and other clean energy technologies as well as substantial decarbonization. The target-driven deep decarbonization of the grid modeled in the Decarb and Decarb+E scenarios yields more extensive solar deployment, similarly extensive deployment of wind and energy storage, and significant expansions of the U.S. transmission system. In 2020, about 80 gigawatts (GW) of solar, on an alternating-current basis,1 satisfied around 3% of U.S. electricity demand. By 2035, the decarbonization scenarios show cumulative solar deployment of 760–1,000 GW,2 serving 37%–42% of electricity demand, with the remainder met largely by other zero-carbon resources, including wind (36%), nuclear (11%–13%), hydroelectric (5%–6%), and biopower/geothermal (1%). By 2050, the Decarb and Decarb+E scenarios envision cumulative solar deployment of 1,050–1,570 GW, serving 44%–45% of electricity demand, with the remainder met by wind (40%–44%), nuclear (4%–5%), hydropower (3%–5%), combustion turbines run on zero-carbon synthetic fuels such as hydrogen (2%–4%), and biopower/geothermal (1%) (Figure ES-1). Sensitivity analyses show that decarbonization can also be achieved via different technology mixes at similar costs.