Boeing recently patented a strange-looking plane. It can fly at a high altitude and is solar-powered. It looks weird because this design is a must, if we want sunlight to hit the solar panels at all times (which we do, lest the plane crash).
Solar panels are attached not only to the wings but also to the “winglets,” those things sticking right up at the tips of the wings. Well, that is the price Boeing has to pay for this aircraft to stay aloft for years! Honestly, it doesn’t even remotely resemble the airplanes we usually see.
But according to Boeing, a 747 equipped with highly efficient solar cells on the upper parts of its wings can only receive 600 kilowatts (800 horsepower) or about 0.8% of what the aircraft requires for it to maintain cruising speed and altitude, even if the cells have 100% efficiency and directly under the sun.
Actual solar cells can only provide around 0.3% of needed power.
Thus, Boeing suggests that this plane should be used for different applications, ones where it has to stay in a fixed position over a certain location. One option is for imaging systems, such as cameras and radars. Another is as for a communication systems for cellphone signals, television broadcasts, etc. It may also be used for measuring wind speed, temperature, humidity, and for other atmospheric sensing purposes. In short, it functions like a satellite, but costs far less.
This means that the power requirement for air transportation is very large as compared to what can be harnessed from solar energy. For now, travelling via solar-powered airplane is far from reality.