Nitpick, the farthest distance of Mercury from the Sun on its orbit is closer to 0.46 AU and it spends most of the time there, so for safe estimate it is better

Nitpick, the farthest distance of Mercury from the Sun on its orbit is closer to 0.46 AU and it spends most of the time there, so for safe estimate it is better to take this greater value for planet-Sun distance. I get around 100x100 km collecting square near the Earth and almost 50x50 km near the Mercury. Taking into account efficiency and design constraints, it's safer to estimate more like 200x200 km near the Earth and 100x100 km near the Mercury. Clearly, building this near the Mercury brings little benefit as opposed to building it near the Earth. If we built this on the surface of the Earth (seems cheapest, even if the area would have to be quadrupled due to night and atmosphere) it does look practically achievable in the future. Solar energy could sustain current consumption of the human civilization. Most alternative sources of energy are not rich enough to supplant nuclear energy. Solar energy seems to be the best contender.