hydro energy is an indirect source of solar energy

You are absolutely correct! Hydro energy is indeed an indirect source of solar energy. Here's the explanation:

The sun is the primary driver of the hydrological cycle.

The sun's heat causes water to evaporate from oceans, lakes, and other bodies of water.

This water vapor rises into the atmosphere and condenses to form clouds.

Eventually, the condensed water falls back to Earth as precipitation (rain or snow).

This cycle creates the potential energy stored in elevated bodies of water like lakes behind dams.  Hydroelectric power plants capture this potential energy and convert it into electricity.