Not just solar panels, how about a two way set of elevated speed mag-trains that run from the Gulf to San Diego area, with spur connections to San Antonio, Albuquerque, and Pheonix. All the panels along the whole lenth could provide more than enough power to motivate several trains in each direction. The remaining power could be used to charge battery/capacitor banks that sit in reserve for the motion activated lasers that shoot anything between the sets of walls
Put a water aqueduct running along the top and suck salt water out of the gulf and convey it to Kalifornia where they can desalt it using solar panels or fill up the Salton Sea.