Not gonna happen, unless one of two other things happens first:
1. A significant orbital industry develops. In such a case the panels could be built in orbit from asteroid or even kunar materials. Far and away the biggest cost of these things is getting them out of Earth’s gravity well and into orbit.
2. Some sort of propulsion system not involving rockets is developed. If we were able to control the gravitational force, for instance, as we do the electromagnetic force, this might be possible. We’re never going to do much in space as long as we can only get to orbit by throwing stuff out the back door.
That would be HUGE (if it doesn't take an exorbitant amount of energy or hard to obtain materials).
Agree that it's a long shot, but with robotics advancing, it might become plausible that a few autonomous robots could be launched, they could mine asteroids and build a solar panel constellation and replicate themselves. Orders could be given from Earth, but after the first launch, the robots get what they need from space.