Comparative Assessment of Space-Based Solar Power and Terrestrial Photovoltaic Systems

Abstract

Sunlight in geostationary orbit arrives at approximately 1,361 W/m², unfiltered by atmosphere, uninterrupted by weather, and available for roughly 99% of the year. On Earth's surface, the same resource averages 150–300 W/m² at mid-latitudes after accounting for atmosphere, cloud, and the diurnal cycle. That gap, nearly an order of magnitude, is the central premise of Space-Based Solar Power (SBSP): collect energy where it is abundant, transmit it wirelessly to where it is needed. This paper quantifies that premise, challenges it economically, and asks whether it survives scrutiny. Using data from NASA, JAXA, ESA, IRENA, and NREL, we show that GEO SBSP concepts could deliver 6–10 times more annual energy per unit collector area than utility-scale terrestrial PV. The cost gap, however, is just as dramatic, NASA's 2024 baseline LCOE for SBSP sits at $0.61–$1.59/kWh, against a global weighted average of $0.043/kWh for terrestrial PV per IRENA's latest figures. The paper also examines two issues the existing literature tends to treat briefly: the specific debris and collision risks posed by deploying large structures in LEO and GEO, and the cost and power expectations for SBSP systems at different scales. A comparative assessment against conventional and modern generation technologies closes the paper, establishing what, precisely, makes SBSP unique and under what conditions it could become competitive.