1.1 billion hectares of land are farmed to feed the 7.5 billion people. That works out to 2000 square meters per person.
World energy consumption (all sources) runs about 18 terawatts, or 2400 watts per person. That is 58kWhr per day. Using an insolation factor of 3.0 (that is a 1W solar panel averages 3Whrs per day) each person will require 20kW of solar panels to replace ALL sources of energy. That is about 100 square meters of panels per person.
That's a lot, but not unthinkable. You could buy 8 pallets of panels today for $13k and cover a person, and it only takes 5% as much land as the land used to feed that person.