Zephyr, which operates on the edge of space, already holds the world duration record at 14 days. Nigel Chandler, the head of sales for the solar electric powered vehicles, says that recent improvements will see the vehicle beat 100 days.
https://www.defensenews.com/digital-show-dailies/farnborough/2018/07/16/airbus-marks-two-milestones-for-zephyr-solar-powered-drone/
https://www.airforce-technology.com/projects/zephyr-s-high-altitude-pseudo-satellite-haps/...The Zephyr S HAPS is powered by two solar-powered electric motors. The solar energy is generated by a combination of solar cells and high-power lithium-sulphur batteries. Each motor drives a two-bladed propeller mounted on the wings.
The UAV is capable of flying at altitudes of 70,000ft and can stay airborne for one month before landing. It can execute missions in air traffic and jet stream winds.
It is suitable for both line-of-sight (LOS) and beyond line-of-sight (BLOS) operations. The BLOS operation is enabled by a satellite communications system of low mass.
The UAV can also transmit real-time imagery, voice and data to areas covering 1,000km² over a long distance....