Assuming you wave a magic wand and get rid of the technical and cost issues, you then run into thermal pollution. You're collecting heat from space and beaming it to Earth and then inefficiently converting it to electricity.

According to [1], the surface of Earth receives 89,300 terawatts of power from the Sun on average. According to the stats at [2], world power consumption in 2008 was ~17 TW. So even if we could somehow build the tens of thousands of these power plants necessary to completely supply the Earth's power needs, and assuming that none of the consumed power ended up being radiated back into space, we would only be affecting the Earth's energy budget by 0.02%.

[1] http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf

[2] http://en.wikipedia.org/wiki/World_energy_consumption

So with a magic wand and an incredible amount of money we'll only make the problem slightly worse.

And it's not clear how slightly -- climate change is being caused by accumulation of greenhouse gases during a period of reduced solar output (cyclical fluctuation of 0.1%). BTW 0.02% seems like a lot more when compared to the sun's cyclical variation of 0.1% (which has measurable effects) and suspected historical variations of perhaps 3% that caused ice ages.

http://en.wikipedia.org/wiki/Solar_variation

http://science.nasa.gov/science-news/science-at-nasa/2013/08...

0.02%, if you are building a hypothetical network of power plants with the same total surface area as the state of Maryland in orbit.