-—Huge progress, in fact.——
To what?
Composites have been around for a while. Are these photovoltaic cells particularly light in weight? What’s revolutionary here? The whole exercise could have been drawn up on a chalkboard, and then erased, saving a lot of time and money.
This could have been done 40 years ago. But no one in the last 40 years wanted to spend their own money on a pointless endeavor. I suspect that government funding was involved in some way.
Nonsense.
Solar cells were neither light enough, nor efficient enough 40 years ago to lift their own weight much less the rest of aircraft. Likewise electric motors. Composites and thin-film polymers 40 years ago were nowhere near strong enough per weight to build an aircraft like this.
If you have to ask what's revolutionary about a lightweight, low maintenance, long duration aircraft which requires no refueling, nor requires fuel at its base ... you're not competent to be having this discussion.
Seriously ... with your attitude, the Bell X-1 would have been drawn on a chalkboard, then erased, saving a lot of money. It could have been done 40 years earlier, but no-one wanted to spend their own money on a pointless endeavour. I suspect government funding was involved in some way.