Solar power satellites are being considered seriously by the EU: https://www.theguardian.com/science/2023/sep/17/tim-peake-backs-idea-for-solar-farms-in-space-as-costs-fall The L5 society's 1980 plan was to build large ones using material from the Moon. Launching that from the Moon's shallower gravity well would be far cheaper than launching that from Earth.