If Earth is not to become a pre-techological subsistence park, it will
*have*
to be solar one day.

Or fusion. Or some form of imported energy (antimatter manufactured down
near the Sun?).

Manmade fusion doesn't exist yet, and antimatter is an energy *sink* (making it
requires more energy than you get from it).
Even for solar, there's no reason why solar power for Earth has to be done
with solar collectors on Earth's surface -- in fact, that's easily the
*worst* place in Earth's vicinity for collecting solar power.

Worst, yeah, but with current space technology, by far the cheapest.
Especially post-shuttle.