During periods of low demand, usually at night, Kruonis PSHP raises water from the lower Kaunas reservoir to the upper one using cheap surplus energy.

With a fully filled upper reservoir the plant can generate 900 MW for about 12 hours.

The KPSP uses hydro-resources of artificial water pools existing at different geographical levels.

At times of electricity output deficit, the Kruonis PSP operates as a regular hydro power plant, letting water flow from the upper pool to the lower pool to generate additional electricity.

[2] A neighbourhood for workers of the Kruonis pumped storage plant was built in the 1980s and early 1990s in Elektrėnai, doubling the size of the town.