During peak power demand periods water will be released from the...

• During peak power demand periods water will be released from the upper to the lower reservoir, passing through reversible pump/generators acting in generation mode. During off peak periods, water will be pumped back from the lower to the upper reservoir with the pump/generators acting in pumping mode. Initial modelling indicates a change in water level of approximately 8m in the upper reservoir and 44m in the lower reservoir during a full generation cycle, with an average water head of approximately 190m over the course of the cycle.

So they are reversing the pumps.
Okay I have some homework to do in this case because the "system" is designed to provide max power but for a limited time. The panels required to push the water back up the hill through the same outlet pumps seems offset to the benefit of just panels to a battery.

Food for thought.
Thanks guys I appreciate your time
Sonic