High Altitude Pseudosatellite (HAPS)

HAPS are electric unmanned aircraft that fly at high altitudes above busy commercial air traffic. They are enabled by solar power to stay aloft for weeks or months at a time. Their current missions include surveillance and providing internet.

Here are some examples:

http://www.airbus.com/defence/uav/zephyr.html

https://www.theguardian.com/technology/2017/jul/02/facebook-drone-aquila-internet-test-flight-arizona