This does not look promising. Powersat suggests that they will be transmitting energy back to the earth at an areal density of less than 230 W/m^2. The sun, when it's shining, is around 1300 W/m^2. With night, clouds, atmosphere, and the like, the average available energy is in the range of 100-200 W/m^2-- similar, but free.
Given that we already have the sun providing us with radiation, why spend the money to build a second one?