Japan’s SoftBank Corp. has launched a four-year program, supported by the New Energy and Industrial Technology Development Organization (NEDO), to develop high-density batteries and high-efficiency solar cells for high-altitude platform aircraft.
Japanese telecom company SoftBank Corp, part of the SoftBank Group, has announced a new four-year project focusing on high-energy density battery technology and high-efficiency solar cells for high-altitude long-duration platform station aircraft (HAPS).
The project partners are the National Institute of Advanced Industrial Science and Technology (AIST), battery energy storage technology specialist Enax, and solar panel manufacturer Choshu Industry.
The research aims to reduce weight and extend component durability, and develop PV and battery technologies for the challenging HAPS environmental conditions.
Such unmanned aircraft operate for extended periods of time at altitudes far above commercial airspace. The lightweight aircraft can be designed to carry a payload such as telecommunications equipment.
For this project, the challenge is to ensure high-altitude operation of solar panels made with thinner and lighter cells and module materials. According to SoftBank Corp. they will also have to withstand the cold solar spectrum at high altitude, low air pressure and strong ultraviolet radiation for a long time.
It may also be necessary to measure systems for operations in higher latitude locations, such as Japan, where sunlight hours are limited in winter.
Battery technology faces similar challenges. “To reduce battery pack weight, it is necessary to assess the performance of next-generation battery cells with high gravimetric energy density (Wh/kg), such as lithium metal batteries, which offer advantages in both weight and volume compared to secondary lithium-ion batteries, and to develop technologies that enable their integration into battery packs,” it said company in a statement.
The project is supported by Japan’s NEDO and must start before March 31, 2026.
SoftBank noted in a statement that this project is a technical continuation of a previous feasibility study on battery storage and solar cell technologies conducted in fiscal year 2024, but with a new financing agreement. The previous work identified key technical challenges and performance requirements. It has also published research on previous HAPS activities, as reported by pv magazine.
NEDO recently outlined its R&D concepts to expand solar energy adoption in Japan.
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