I'm not sure what you're getting at. Do you know how many solar panels it would take to provide substantial energy to a burgeoning world population? I don't know but I assume you would have cover massive tracts of land with them that you could probably see from orbit. It would be prohibitively expensive. That cost would be passed on. Not only that, but in the production of said panels a toxic waste is produced. When oil starts to run out, competition for alternative energy sources such as coal will skyrocket, and so goes the price. The bottom line is that nothing can be as cheap and abundant as something that can be pumped from the ground and cheaply processed by a cracking plant.