Solar Panels - How to Get the Power Down to Earth?

Solar panels in space could direct the energy where it's needed on earth. The power would get sent to some giant station that collects it, and then it would be sent through the grid to our houses. One of the biggest questions they have to deal with is how to get this power down to earth. Micro waves are just another kind of light, but it's light with a specific wave length. And so you might need rays on earth that are one to three kilometers wide just to capture this energy.