Space-based solar power has been gaining more and more traction recently. The recent success of Caltechs Space Solar Power Project, which demonstrated the feasibility of transmitting power from space to the ground, has been matched by a number of pilot projects throughout the world, all of which are hoping to tap into some of the almost unlimited and constant solar energy that is accessible up in geostationary orbit (GEO). But, according to a new paper from a group of Italian and German researchers, there are plenty of constraints on getting that power down here to Earth - and most of them are more logistical than technical.