There is plenty of energy on Earth but Mars will be energy short for a long time. Energy = Civilisation.
Solar panels in Earth orbit beaming power to Earth have been considered but it is still far cheaper to just install solar panels on Earth.
Vertically orientated panels (solidly fixed on Earth) mean land below is still available for use.
Orbit solar panels, that's a very interesting concept!
You can read about it in Dr Robert Zubrin's new book The New World on Mars.
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