The sites are connected by a 12km, 11,000V underground cable which terminates at Caban Coch, the lowest reservoir in the system. Situated at the top of Claerwen Valley, Claerwen reservoir has the largest power store and water is released via either of two 1.2m-diameter pipes, each side of the dam base. The new turbine house has been built below ground level and one of the pipes has been extended to connect to a Francis 1680kW turbine. Water released from the turbine returns to the River Claerwen which flows into Caban Coch. At the top of Elan Valley, Craig Goch has the largest catchment area, which means that the reservoir fills and empties faster than the others.
Water is released via a pipe which runs through a tunnel at the base of the dam.
A Francis 480kW turbine has been installed in a new turbine house situated over the end of the tunnel. The discharge pipe has been re-directed to the inlet of the turbine, which discharges back into the tunnel. Caban Coch is the only reservoir in Elan Valley where turbines had previously been installed. The two original turbine houses are still in use, one on each side of the river. The north house contains an old Francis turbine, though not the original, and the south house contains a new Francis 950kW turbine.