The idea that some of the electricity we use daily could come from outside the atmosphere sounds like science fiction, but Japan is taking that possibility very seriously. Through an ambitious program of solar energy from spaceThe Asian country wants to test whether it is feasible to capture sunlight in orbit and then send it to the surface as usable electricity almost continuously.
This approach aims to go beyond the panels installed on roofs or large plants in soil, which depend on the climate and the day-night cycle. In space, the sun is available for much longer and with greater intensity, which opens the door to new forms of renewable generation capable of reinforcing the electrical grid when terrestrial production is insufficient.
OHISAMA: The Japanese satellite that wants to shine a light from orbit
Japan's first practical step in this race is called OHISAMAIt is a small experimental satellite designed as a technology demonstrator, not as a commercial power plant. According to data published by Japan Space Systems (J-spacesystems), the device will have an approximate mass of 180 kilograms and will feature an integrated generation and transmission panel measuring approximately 70 centimeters by 2 meters.
With that configuration, the satellite will have around seven hundred and twenty watts of electrical powerThis figure is comparable to the energy consumption of a medium-sized household appliance running for one hour. It's a modest capacity compared to a conventional power plant, but sufficient to verify that the entire technological chain functions correctly, from low Earth orbit to a ground-based antenna.
The launch of OHISAMA is planned for fiscal year 2026 aboard a small Japanese commercial rocket. Once in low Earth orbit, around the four hundred and fifty kilometers highThe satellite will capture sunlight, convert it into electricity, and then transform that energy into microwaves to send them wirelessly to the surface.
The goal of the experiment is to power a lighting system connected to a large parabolic antenna located at the Usuda Deep Space Center in Nagano Prefecture. On paper, it may seem like a simple test—turning on some lights—but for the Japanese scientific community, it's a crucial test: if the signal arrives with sufficient strength, it will mean that wireless power transmission from space It works beyond the laboratory.
From theory to the laboratory: what has already been achieved on Earth
Japan is not starting from scratch in this area. Ground-level tests have already achieved significant wireless energy transmission. Controlled tests have been conducted to send 1,8 kilowatts at about 55 meters distance and up to 10 kilowatts at about 500 meters, maintaining reasonable efficiency for a system under development.
The country has also taken experimentation into the atmosphere. In 2024, Japanese researchers conducted a demonstration in which energy was transmitted from an airplane to a few seven kilometers high down to an antenna on the surface. These intermediate steps have served to fine-tune materials, electronics, and beam control algorithms before making the leap to orbit with OHISAMA.
These advances are part of a global trend in which universities and space agencies in the United States and Europe have also tested small prototypes of space solar energyHowever, the Japanese project aspires to something more ambitious: to convert, for the first time, energy captured in space into usable electricity at a specific point on the surface, and not just a weak signal detected by instruments.
Japanese authorities have included this line of work in their medium- and long-term energy planning. It is not yet a solution to lower electricity bills, but rather a large-scale technological laboratory which could determine whether it is worth investing in large solar power plants in orbit starting in the 2040s.
Why solar energy from space is different from what we already know
The underlying motivation for these projects lies in the physical limitations of surface-mounted renewable energy generation. Solar and wind power production depends on factors we all know: clouds, rain, hours of daylight, and windThis variability forces the use of gas or coal-fired power plants when renewables do not meet demand, especially during peak consumption times or at night.
In orbit, many of those constraints disappear. At the altitude of the platforms, the Sun shines with a intensity approximately 40% greater Because it's on the ground, there are no clouds or day-night cycles as pronounced as those affecting terrestrial facilities. According to studies by the Japanese government itself, a commercial space-based solar power station could operate with utilization factors close to 90%, far exceeding many conventional solar plants.
The reference model used by Japan Space Systems is based on platforms located in geostationary orbit, at about 36.000 kilometers altitudewith enormous solar panels covering approximately 2,5 square kilometers. The collected energy would be converted into microwaves and directed towards a recten -a special receiving antenna- on the surface, with a diameter of about 4 kilometers.
Preliminary calculations suggest that a single one of these platforms could supply on the order of one gigawatt of powerThis figure is comparable to that of a large power plant. In the case of Japan, this volume would be sufficient, on paper, to cover slightly more than 10% of the annual electricity consumption of its capital, Tokyo, which gives an idea of the potential if the system is scaled up.
In addition to mass generation, the direction of the microwave beam can be adjusted within certain limits, allowing different areas to be prioritized according to specific needs. In practice, this could be used to strengthen supply in regions affected by heat wavesIt could support damaged grids after a major blackout or stabilize nighttime demand when the wind isn't blowing. It wouldn't replace onshore renewables, but it could become another piece of a much more flexible electricity system.
How do energy “beams” sent from space work?
The key to this approach lies in a combination of technologies that, individually, are already known, but which here are taken to a completely new scale. In orbit, the panels convert sunlight into electricity, just like in any photovoltaic installation. That electrical energy is then used for generate microwaves, a type of electromagnetic radiation similar to that used in communications, but adjusted in frequency and power to maximize transmission efficiency.
Since laying a cable tens of thousands of kilometers long is impractical, energy travels through space in the form of electromagnetic waves. The challenge lies in focusing that beam with enough precision so that most of the power reaches the exact point of impact. rectena on the surfaceAny mismatch would imply significant losses or, in the worst case, a deviation that would send energy to an unwanted area.
To avoid this, the system relies on a kind of very precise “electronic aiming.” The receiving antenna on the ground emits a pilot signal toward the satellite; from this reference, the transmitting panel adjusts in real time the phase of thousands of antenna elements to concentrate the beam on the correct target. It's a kind of Planetary-scale electricity Wi-Fibut with many more layers of control and security.
This approach isn't entirely new: several countries had explored similar ideas in previous decades, although many of those initiatives were hampered by costs or a lack of suitable components. The difference now is that power electronics, lightweight materials, and space technologies have advanced enough for projects like OHISAMA to seem, at least, technically feasible.
Meanwhile, companies and research centers in the United States, China, and Europe are closely monitoring the Japanese tests as they prepare their own demonstratorsAlthough most are still in very preliminary stages, the global movement indicates that solar energy from space has ceased to be a curiosity and has become a possible long-term strategic approach.
An electrical grid that looks to space: opportunities and limitations
Beyond the Japanese case, the idea of an electrical grid supported by orbit has implications for regions such as Europe and Spainwhere the massive integration of renewables already poses daily management challenges. The possibility of having almost continuous sources of generation, independent of local weather, could help reduce dependence on fossil fuels during periods of lower wind or solar production.
In future scenarios, it is envisioned that several space platforms could modulate the power sent to different areas depending on the state of their networks. Thus, a single station could deflect the beam to reinforce specific areas during peak hours, support isolated systems, or help in recovery after natural disasters where the electrical infrastructure has been damaged.
For Europe, which already has a strong aerospace industrial base and renewable energy capabilities, these developments open the door to collaborations in research, safety standards, and potential joint demonstration projects. The European Space Agency, for example, has begun to study the feasibility of various concepts for space-based solar power plantsalthough still without a program as defined as the Japanese one.
In the Spanish case, experience with large solar plants and grid management systems could be a valuable asset if, in the medium term, the construction of rectennas or other ground-based receiving infrastructure is considered. However, any involvement would first require a broad political, regulatory, and social debate on the role of this type of infrastructure within the national and European energy strategy.
Costs, safety and environmental footprint: the big questions that remain
If the theory is so appealing, the less appealing part comes with the numbers. A recent analysis prepared under the umbrella of the american space agency It is estimated that, with current technology, electricity generated by space-based solar power plants would cost approximately $0,60 per kilowatt-hour. In comparison, energy produced by ground-based solar or wind farms costs around $0,05 per kilowatt-hour, an order of magnitude cheaper.
This difference reflects the enormous complexity of manufacturing and assembling structures several kilometers across in space, as well as the economic impact of the numerous launches required to deploy a single station. Although rocket prices have been decreasing with the entry of new private players, this gap remains one of the major obstacles to considering a single space station. massive commercial exploitation.
Another critical point is ensuring that the microwave beam always remains within safe limits. Control systems have been designed so that, in case of deviation, the transmitted power is rapidly reduced, but experts insist on the need for international certifications and independent monitoring to minimize any risk to people, wildlife or aviation.
Added to this is the debate about the global climate footprint of the infrastructure. The rockets that would place the modules of these power plants into orbit emit greenhouse gases and particulate matter into the upper atmosphere, with large-scale effects that are still poorly understood. Furthermore, issues such as recycling in spacecraft And the sustainability of the components themselves still requires robust technical and regulatory development. Proponents of the concept point out that, once deployed, the platforms could operate for decades and displace a significant portion of fossil fuel generation, but other scientists are calling for more in-depth analysis. environmental impact and sustainability before planning complete constellations.
For now, the main agencies agree that the horizon for a possible realistic commercialization is more towards the 2040s, and always conditional on the intermediate demonstrators working and the decrease in costs in launchers, power electronics and space manufacturing continuing at the expected pace.
Given all these constraints, the OHISAMA mission is best understood as a starting point in a very long process. If it succeeds in powering a lighting system in Nagano with energy captured directly from space, it will demonstrate that a key part of the concept is viable. From then on, the debate will focus less on "if it's possible" and more on "to what extent it's worthwhile" to invest in large solar power plants in orbit as a complement to the renewable energy sources we already know.
Overall, Japan's commitment to solar energy from space reflects an attempt to broaden the range of solutions to climate change and dependence on fossil fuels, exploring options that just a few decades ago seemed purely theoretical; upcoming missions, both in Japan and in Europe and other countries, will help clarify whether this type of infrastructure can become a pillar of the electrical system or will remain a niche technology reserved for very specific cases.
