Solar energy projects have already reached the point where they can operate profitably (be self-sustaining) under certain circumstances. If the variables are calculated correctly (the solar park is just the right size - neither too small nor too large - to consume the energy produced from one day to the next - without having to store it for a long time -), then it operates at practically zero cost...it only has the costs of creation, which (under ideal circumstances) are recovered in 8-10 years (and the solar park can operate at maximum or close to maximum efficiency for 25-30 years.