Hydropower is almost always accessible. Most of time you can run the plant and generate electricity without much water.
Once built, hydropower plants need very little maintenance UNLIKE solar energy.
Other surroundings will not affect the efficiency of the plant unlike solar power.
You cannot access solar power ALL the time.
Trees and other building will affect the sunlight.
Maintenance of your panels can also be a problem. Outside of basic solar panel maintenance, repair of your panels must be performed by a certified energy technician. Finding such a technician can be costly.