Here is the challenge that the Japan decided to tackle: transform an idea of Peter Glaser, which seemed too expensive and complex in 1968, into a concrete technology, capable of providing clean and continuous energy to the Earth. As? Capturing the sunlight not with the panels on the roof of the house, but directly into spacewhere the Sun never sets and there are no clouds to block the rays.
More specifically, the OHISAMA project for space photovoltaics managed to make a satellite covered with panels solar (placed 450 km away from Earth), which collected energy for later transmit it wirelessly to a receiving station in Japan. Let’s see how the project works and what the future objectives are.
The progress achieved in space photovoltaics
In recent years the Japanese Space Agency (JAXA), together with universities and companies, has conducted several tests to demonstrate the feasibility of space photovoltaics. Already in 2015 a team managed to broadcast 1.8 kilowatts of energy at 50 meters away using microwaves. This energy is enough to power an electric oven. In 2025 the project OHISAMA (which means “Sun” in Japanese) has taken a decisive step. This is a experimental satellite of approximately 180 kg, with a surface area of approximately 2m2 covered by solar panels and located about 450 km away from Earth. This satellite has collected solar energy in space and has transmitted wirelessly to a receiving station on Earth, in Suwa, Japan. This achievement marks the first full-scale demonstration of wireless photovoltaic power from space.
According to researchers from Kyoto University and the New Energy and Industrial Technology Development Organization (NEDO), tests confirmed that the transmission is stable and safe.
The real revolution lies in the fact that the Sun in space it never sets: Orbiting photovoltaic panels can collect energy 24 hours a day, without interruptions due to clouds, rain or day-night cycles. Furthermore, the energy transmitted via microwaves does not depend on local atmospheric conditions. Compared to terrestrial panels, this technology promises a production continuity and one higher energy densitybecause solar radiation in space is not filtered by the atmosphere.
Future goals
Japan is a country with few natural resources and a strong dependence on foreign energy. After the 2011 Fukushima disaster, confidence in nuclear power declined and the need for safe and sustainable alternatives arose.
Investing in space photovoltaics means focusing on a source clean, inexhaustible and independent of imports. Furthermore, the project is part of the national strategy for reducing emissions and transitioning towards climate neutrality. In the coming years, therefore, Tokyo wants further experimental demonstrations with small satellites. It will then develop from 2030 to 2040 larger systems in geostationary orbitcapable of providing hundreds of megawatts. The final target is to create real Space solar power plantsintegrated into the terrestrial electricity grid.
The I walk towards large-scale use of space solar remains long and complex. Among the most relevant critical issues is safety and the environmental impact linked to the transmission of large amounts of energy via microwaves through the atmosphere. Scientists will have to carefully check whether these beams can cause heating or ionization of the air, with possible effects on the climate. Added to all this is the problem of costswhich are currently still very high.
