This is very clever: instead of focusing on electric only flight, just make the existing engine fly in the most efficient window while the electric engine buffers the flight profile.

Like a big-boy prius.

I kind of wonder how the orders of magnitude work out for solar and wing area.

Solar cells are actually quite thin and could be almost like paint on the wings of aircraft. I wonder if the energy generated vs required is even ballpark. There is plenty of sun at 30,000 feet during the day.

More like an Edison Motors hybrid system.