Many companies around the world are trying to develop technology to exploit solar power in space with the goal of providing abundant clean energy for the Earth.
Simulation of Space Solar’s Cassiopeia station operating in orbit. Image: Space Solar
Solar power in space works similarly to Earth, using photovoltaic cells to convert sunlight into electricity. This energy source has the huge advantage of being located above the atmosphere, so that photovoltaics can collect unfiltered sunlight through the layers of gas and clouds that cover the Earth. According to Earth Observatorythe atmosphere reflects about 30% and absorbs about a quarter of the energy transmitted to the planet. Photovoltaic cells in space can avoid this effect and be exposed to sunlight almost continuously if placed in the right orbit.
Once collected, solar energy can be transmitted back to Earth in the form of microwaves or laser beams, collected by large antennas on the ground, and converted back into usable electricity. However, to be economically viable, each satellite must produce and transmit gigawatt-level amounts of electricity, requiring the assembly of massive battery arrays in orbit. According to David Homfray, co-founder and chief technology officer of Space Solar company in the UK, solar power in space will help promote the energy transition. Some estimates indicate it could meet 80% of Europe’s renewable energy needs, mainly due to a power density 10 times higher than on the ground.
Aetherflux, a startup company in California, USA, plans to deploy a cluster of satellites equipped with high-power infrared lasers and photovoltaic batteries in low Earth orbit. These satellites will collect solar electricity and transmit it to collection points on the ground. To ensure safety, each laser is designed to turn off immediately when any object is in the way. The laser is too weak to cause serious damage like destroying an airplane but still strong enough to affect health. According to Baiju Bhatt, the company’s founder, this technology can be useful in locations that lack electricity.
In April 2025, Aetherflux announced that it had called for 50 million USD in investment capital. They are planning to launch a test satellite in 2026 to transmit a kilowatt or 1.3 kW laser to photovoltaic panels on the ground. However, the company did not share any details about how the infrared laser transmission system performed in testing.
Space Solar Company in the UK pursues a different approach with the ambition to build large city-sized solar power plants in space that can transmit enough electricity for the entire country. With a budget of $1.6 million from the British government, Space Solar plans to launch two test missions in the next three years, one to transmit electricity to the ground using radio waves and one to demonstrate that robots can build large structures in space.
The company’s ultimate goal is to build a 1.8 km wide structure in space called Cassiopeia. Located 36,000 km above Earth in geostationary orbit, the station will use millions of table-sized satellites covered with photovoltaic cells to collect incoming sunlight. About a billion antennas will transmit the received electricity to a receiving station the size of Heathrow airport on the ground, in charge of converting radio waves into electricity.
Homfray said a Cassiopeia station can reach a capacity of about 700 MW, enough to supply 500,000 households in the UK. In early 2025, Space Solar announced that the company had built experimental robots to build the structures necessary for the above technology in space. Last year, they also tested 360-degree wireless energy transfer in a lab at Queen’s University Belfast in Northern Ireland.
American company Virtus Solis is also developing solar power generation technology in space, concentrating 200,000 honeycomb-shaped satellites in a large constellation spanning kilometers. Those constellations will be located in the Molniya orbit, an elliptical orbit with a high inclination that allows satellites to stay for a long time at high latitudes and transmit power to the Northern Hemisphere. Virtus Solis’ plan is to launch a test mission in 2027. According to company founder and CEO John Bucknell, if they are successful, energy costs on Earth could be significantly reduced. The global average electricity price is about 75 USD/megawatt hour, but solar power in space according to Virtus Solis’ model can reach a price of 0.5 USD/megawatt hour.
The challenge when exploiting solar power according to the above methods is launching and operating many satellites at the extremely large scale that companies propose. According to Francesca Letizia, a space debris expert at the European Space Agency, managing hundreds or thousands of satellites and preventing them from colliding with each other is very difficult. Any accident could prevent this nascent industry from growing.
A 2024 NASA report points out that current space-based solar power generation technology is much more expensive than terrestrial renewable sources and is only feasible with major advances in launch operations, production and efficiency. Karen Jones, a space economist and technology strategist at the British non-profit organization The Aerospace Corporation, emphasized that international cooperation is needed to make this energy source a reality.