A team of student engineers from the National University of Singapore has built a quadcopter drone powered entirely by sunlight.

The prototype has flown above 10 meters (about 33 feet) in test flights with no onboard battery or any other storage system, according to a press release.

The drone is constructed from lightweight carbon fiber and weighs only 2.6 kilograms (about 5.7 pounds) and has a surface area of about 4 square meters (43 square feet). It features 148 silicon solar cells, four rotors and can be controlled remotely or fly autonomously thanks to a built-in GPS system.

"Our aircraft is extremely lightweight for its size, and it can fly as long as there is sunlight, even for hours," associate professor Aaron Danner, one of the supervisors of the project, said in the press release. "Unlike conventional quadcopter drones, our aircraft does not rely on on-board batteries and hence it is not limited by flight time. Its ability to land on any flat surface and fly out of the ground effect in a controlled way also makes it suitable for practical implementation."

The university touts that the aircraft can be used as a "flying solar panel" to provide emergency solar power for disaster sites. It can also be used for photography, package deliveries, surveillance and inspection. The drone can also be modified to include batteries so it can store energy generated by the panels, or fly when it's cloudy or dark outside.

Eight groups of students have tinkered at the project in successive years since 2012. The latest team, comprised of then-final year engineering students, achieved fully solar-powered flight with their latest prototype.

"We encountered many engineering challenges when building the drone. These included finding an optimal number of solar cells efficient and light enough to power the propulsion system, which in turn has to be light and at the same time able to produce sufficient thrust to lift the aircraft," said Brian Shohei Teo, one of the supervisors of the project, in the press release.

"Other issues we faced included tuning and calibration of flight controls to enhance flight stability, as well as designing a frame that is lightweight yet sufficiently rigid. This has been an excellent learning opportunity for us."

The drone is described as Asia's first fully solar-powered quadcopter. Another student team from Queen Mary University of London reportedly built one five years ago, according to New Atlas.

"To be able to make something fly under control for a long time is a very complex engineering problem. Our students have attained flight in its purest form, powered by natural sunlight. This is an amazing achievement," Teo said.

The engineers will continue fine-tuning the aircraft to further improve its efficiency with the hope of bringing the technology closer to commercialization.