Focus is what you're lacking.
Premise -- A Fresnel lens 3 km in diameter would deliver 14 trillion watts of electricity to Earth.
Problem -- What orbit should the Fresnel lens occupy?
SM. The amount of power delivered depends on the integrated intensity of light that enters the lens, if we assume that you have the proper optical configuration to get it in the neighborhood of Earth.
The orbit that it occupies, with small exception, depends on the distance to the sun. Is the 3km lens near 1AU or what?