That is only one of the multiple problems discussed with mass pumped storage. Regardless, the efficiency does matter as if you are attempting to store peak powe

That is only one of the multiple problems discussed with mass pumped storage. Regardless, the efficiency does matter as if you are attempting to store peak power as %100 of baseline power then your input is no longer free. It is a factor in the energy output of the PV / Turbine over the course of its lifecycle. Lower efficiency means more PVs / Turbines and more massive pumped storage projects.