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How to create near-constant multi-terawatt electricity on Mars: millions of solar sails operating as mirrors in areosynchronous orbit, deflecting sunlight to a 100km by 100km solar array on the surface, quadrupling the light intensity and illuminating it night and day. 
Solar cells are currently as cheap as 8.5 cents per Watt. ~$130billion worth of cells with 2000W/m^2 illumination gives you about 3 terawatts over a 100km by 100km array (a little less if it's circular).
100km diameter is about the spot size of the light reflected from a flat mirror 20000km away above the Martian surface. So this is really the size of array you need to build in order to efficiently gather the reflected light.
To quadruple the light received (and provide it at night) would require 100km*100km*4 solar sails, with solar sails about 5 micron thick on average, with a density of about 1.4grams/m^2... You need about 280,000 tons of solar sails.
But they can actually sail themselves to Mars orbit, so you just have to launch them to LEO. At $10/kg, that's only $3 billion in launch for the solar sails. We can scale that up for terraforming later if we wish.
But thousands of square miles of solar sails in orbit of Earth would probably make people mad, which is why I proposed Mars.
What could Martians do with more electricity than the entire Earth currently produces? Probably lots of stuff you could make.
