The flight proves that the plane’s solar collectors can store enough energy through the day to last through the night.
Not quite. You need to look at the sunrise and sunset times. At this time of year, and in that location, all that's been proved is that the plane can collect enough energy in 15 hours of daylight to sustain a 9 hour night flight (roughly). It's an important proof of concept, certainly, but they're a way from flying indefinitely. At the very least, they have to prove they can do this in winter.
Not quite. You need to look at the sunrise and sunset times. At this time of year, and in that location, all that's been proved is that the plane can collect enough energy in 15 hours of daylight to sustain a 9 hour night flight (roughly). It's an important proof of concept, certainly, but they're a way from flying indefinitely. At the very least, they have to prove they can do this in winter.