There is other current work going on in this area, particularly by the Japanese. I don't think anyone doubts the feasability of a downlink. The bigger problem is making the solar array big enough to matter.

For that, the key technology seems to be making the solar cells thin enough that they could be part of a huge, unfoldable expanse. Since people are already talking about solar cells as a film placed on office building windows, it seems that ought to be doable too. Akin to the unfoldable Webb telescope heat shield but of course much bigger.

Then there is the question of what to do about micrometeors, so there would have to be some redundancy in the design. None of it sounds impossible.