Updated by Bill Lofton 4/29/16
Courtesy of SOLAR IMPULSE on YouTube
The easiest way to distinguish the two aircraft is by location of the motor nacelles: on Solar Impulse 1, the two motor nacelles on each side of the fuselage are far apart, whereas on Solar Impulse 2, they’re close together.
Also, the tail booms are distinctive: on Solar Impulse 1, the tail boom height is about 1/2 of the height of the fuselage under the wing, whereas on Solar Impulse 2, the tail boom height is about 3/4 of the height of the fuselage under the wing and the tail boom height is tapered aft.
Solar Impulse 2 Background
Intro to Solar Impulse 2
Solar Impulse 2 vs. Solar Impulse 1
Solar Impulse 2 Solar Power System
Solar Impulse 2 Electric Propulsion System
Solar Impulse 2 Propeller
Solar Impulse 2 Battery System
Solar Impulse 2 Press, Other Info, and Videos