An octocopter designed by Aleksey Zaitsevsky of Ecilop that flies only using power derived from solar panels. No large payload and only flight in ground effect but like many of these things its a first. Only time will tell what applications might spawn from this. If you want to have a go at building your own Aleksey has kindly created a BOM and calculations here.
In the words of Aleksey
The drone is controlled as a quad-copter, 8 rotors are connected pair-wise. There is no onboard battery. To configure controllers inside a building, the user connects an external battery. To restart the controller in sunlight, the user bridges the power leads. The vehicle remains airborne because of ground effect and automatically maintains a horizontal attitude. If the control panel allows mixing of control signals for the multicopter’s different motors, no on-board flight controller need be installed. We utilized a mirror to concentrate solar energy in order to raise the vehicle higher off the ground. This is not a commercial project and the drone is not available for purchase.