It might not work as well as you expect: the air temperate may be low, but because the pressure is close to a vacuum the air is also a great insulator, and your material is in stronger direct sunlight.
Also politically speaking this may just be a non-starter: on paper, we can already build a conventional low-resistance[0] ground-level planetary power grid for very reasonable prices and material requirements, but much smaller projects connecting Europe to the Sahara have stalled.
[0] 1 Ω at 40,000 km
[1] material costs of a few hundred billion USD, a little over a year of current global aluminium production, more to actually install it