Convert to steam/vapor. Run a hyper-insulated pipe up the side of a mountain with repeater heaters if necessary. Condense at the top, recovering the heat, and send them both (the water and the heat) back to the bottom separately. For added points make up your losses from solar inputs.
Moving ambient temperature water through an appropriately sized pipe is nearly lossless from an energetics perspective. Moving steam through a pipe of any length is far more lossy even with significant amounts of insulation.
on netflix is a show called "islands of the future" and in one of the episodes they did in fact pump excess water back up the mountain. I think their location was already hot enough that they didn't consider converting to steam.
Don't pump water up.
Convert to steam/vapor. Run a hyper-insulated pipe up the side of a mountain with repeater heaters if necessary. Condense at the top, recovering the heat, and send them both (the water and the heat) back to the bottom separately. For added points make up your losses from solar inputs.