For more than a decade, the world has steadily expanded its solar power capacity, driven by the urgent goal of achieving carbon neutrality and tackling climate change. Yet, while conventional solar energy has become central to the clean energy transition, its limitations have left researchers searching for new frontiers. Japan is now reaching beyond the atmosphere, aiming to capture sunlight in orbit and beam it directly back to Earth.
Traditional solar power, despite its popularity, is far from flawless. Its efficiency suffers from weather dependency and intermittency, it requires vast stretches of land that can disrupt habitats and agriculture, and its production process involves rare and sometimes toxic materials such as cadmium and lead. These environmental and logistical drawbacks have sparked interest in alternatives that bypass Earth’s constraints altogether.
Japan has emerged as a pioneer in this effort. The organization Japan Space Systems is preparing to launch a groundbreaking project called OHISAMA, designed to collect solar energy in orbit and transmit it back to Earth. If successful, the mission could mark a new chapter in renewable energy. The plan involves sending a 180-kilogram satellite into low Earth orbit at around 400 kilometers. Equipped with a two-square-meter photovoltaic panel, the satellite will capture solar radiation, store it in onboard batteries, and then beam it down to a terrestrial receiving station in the form of microwave energy.
Although OHISAMA’s pilot system will only deliver about one kilowatt—just enough to power a small appliance—the implications are far greater. Adviser Koichi Ijichi stressed its significance, saying, “This mission marks a pivotal step towards realizing space-based solar power stations that could provide clean energy irrespective of weather conditions on Earth.” The vision is for future orbital systems to scale up dramatically, potentially generating continuous, weather-proof power that could rival conventional plants.
Japan is not alone in pursuing space-based solar power (SBSP). China has already announced its ambition to develop the world’s first orbital solar plant, while other nations are experimenting with advanced satellite designs. According to RatedPower, orbital solar platforms have the potential to generate up to 13 times more energy than ground-based panels, with output levels that could match nuclear power facilities.
Yet challenges remain. A NASA report in early 2024 noted that the costs of launching assemblies into orbit remain prohibitively high and that rocket emissions could offset the climate benefits of space-based power. This raises concerns that SBSP might, for now, be less eco-friendly than the solar farms already operating on Earth. However, technological progress in launch vehicles, photovoltaic materials, and wireless transmission continues to improve the outlook.