Japanese telecom company SoftBank Corp, part of the SoftBank Group, has announced a new four-year project focused on high-energy density battery technology and high-efficiency solar cells for long-duration high altitude platform station (HAPS) aircraft.
Its project partners are the National Institute of Advanced Industrial Science and Technology (AIST), battery energy storage technology specialist Enax, and solar module manufacturer Choshu Industry.
The research aims to reduce weight and extend the durability of components, as well as develop the PV and battery technologies for the challenging HAPS environmental conditions.
Such uncrewed aircraft operate for extended periods of time at altitudes well 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 modules made with thinner and lighter cells and module materials. They will also have to withstand cold, high-altitude solar spectrum, low air pressure, and strong ultraviolet radiation for long periods, according to SoftBank Corp.
There may also be a need to gauge systems for operations at higher latitude locations, such as Japan, where sunlight hours in the winter are reduced.
The battery technology has similar challenges. “To reduce the weight of the battery pack, 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 reduction compared to lithium-ion secondary batteries, and to develop technologies that enable their integration into battery packs,” said the company in a statement.
The project is backed by Japan's NEDO and is to begin before March 31, 2026.
SoftBank noted in a statement that this project is a technical continuation of an earlier feasibility study of battery storage and solar cells technologies conducted in fiscal 2024, but with a new funding agreement. The earlier work identified the key technical challenges and performance requirements. It has also published research on earlier HAPS activity, as reported by pv magazine.
NEDO recently outlined its R&D concepts to expand solar adoption in Japan.
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