My understanding is that Walchensee is just a Hoover-Dam-Style station with additional flow diverted from other rivers. That's a traditional hydroelectric generating station, not a pumped hydro storage system like Dinorwig.
Dinorwig's upper lake doesn't have a very large catchment area for rainfall, so most of the water that flows down the pipes was previously pumped up the same pipes.
My understanding is that Walchensee is just a Hoover-Dam-Style station with additional flow diverted from other rivers. That's a traditional hydroelectric generating station, not a pumped hydro storage system like Dinorwig.
Dinorwig's upper lake doesn't have a very large catchment area for rainfall, so most of the water that flows down the pipes was previously pumped up the same pipes.