The Ladce hydroelectric power plant is the oldest operated hydroelectric power plant on the Váh river – in service since as early as 1936. It was built however at the time that the electrification was only getting off the ground and electricity supply demands were low. As a result, it was designed to a low flow rate – 120 m3.sec-1. All of the downstream and upstream HPP´s alike have a higher maximum usable flow, therefore the Ladce HPP constitutes a so-called bottleneck on the Váh river. Over the period between 1999 and 2001 the Ladce HPP had been reconstructed up to a flow rate of 2 x 90 m3.sec.-1, thereby also raising its installed capacity from 13.8 MW to 18.9 MW.
Slovenské elektrárne operates 31 hydroelectric plants. Their combined output is 1,652.7 MW, representing approximately 38.4% of the Company’s total installed capacity. Majority of the installations is located on the Váh River cascade, or the longest river in Slovakia. On average, the hydroelectric sources generate 2,070 MW annually (consumption of pumped storage power stations excluded), or some 11% of the electricity produced by Slovenské elektrárne.
Because of their very variable power output and operational flexibility, hydroelectric plants are capable to satisfy the swiftly changing demands in the daily-load diagram, pairing nicely with the base load supply covered by nuclear power plants. Slovenské elektrárne has 736.6 MW installed in river hydropower plants and 916.4 MW in pumped storage power stations.