China is promoting the Sun Chasing project to develop space-based solar power systems that collect energy in orbit and transmit it wirelessly to Earth or spacecraft for a continuous power supply. Early tests demonstrated wireless power transmission over 100 m and efficient microwave radiation to moving targets, with power output up to 1,180 W and promising system efficiency.
A research team from China’s Xidian University has begun initial experiments as part of the Sun Chasing project, an initiative aimed at developing large-scale space-based solar energy systems. The long-term goal is to deploy orbital solar energy infrastructure capable of collecting energy in space and wirelessly returning it to Earth or to spacecraft, potentially creating a continuous and weather-independent energy source.
The research team reports that it has successfully demonstrated wireless power transfer over distances of more than 100 meters to a stationary target, as well as over distances of more than 30 meters to a moving target. According to the project team, these early tests are intended to validate key components of the system, including beam stability and energy delivery accuracy under changing conditions.
“In recent tests, the system achieved a wireless power transmission efficiency of 20.8% from DC to DC over a distance of 100 meters. It delivered 1,180 watts of power,” China’s State Council Information Office said in a statement. “The team also built a wireless charging system for drones. In one test, a drone flying at 30 kilometers per hour was able to receive 143 watts of stable power from 30 meters away.”
In the proposed system configuration, solar energy is first collected using spherical crown concentrators, which are designed to efficiently collect and focus incoming sunlight over a large surface area. This concentrated solar energy is then converted into electrical energy via on-board conversion systems. Once converted, the energy is converted into microwave radiation for wireless transmission.
The microwave signal is generated and guided by a circular active phased array antenna with a diameter of 1.2 meters. This phased array enables precise beam steering and control, allowing microwave energy to be tightly focused on a designated receiving station despite distance and relative motion.
At the receiving end, the emitted microwave beam is received by a rectifying antenna, called a rectenna, with a diameter of 5.2 meters. The rectenna converts the incoming microwave energy back into usable electrical power with high efficiency, reportedly capturing approximately 87% of the emitted microwave power under the test conditions.
The Sun Chasing project was initiated in 2018 and reached a major milestone in 2022 with the completion of a ground validation of the entire system. In 2024, the team reported successful power transmission over a distance of over 55 meters.
“Recent breakthroughs include improving the efficiency of solar energy collection and conversion, increasing the precision of microwave beam control to reduce energy loss, and making the transmitting and receiving antennas smaller and lighter, which is critical for space applications,” said Duan Baoyan of Xidian University. “We also solved the problem of how to power multiple moving targets simultaneously using a single transmitter. This means that in the future, one space power plant could potentially provide electricity to multiple satellites or ground vehicles simultaneously.”
However, the researchers noted that there is still a long way to go before a space-based solar power plant becomes a commercially viable reality. “The next step is to conduct tests in space,” they said.
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