How do dams make electricity?

By letting water fall. A dam holds a lake high above the river below it. Near the bottom, the water rushes down a huge pipe and pushes against the blades of a turbine, spinning it like a giant propeller. The turbine turns a generator, where magnets spin past coils of wire, and that makes electricity flow out along the wires to towns and houses.

The water had to get up high in the first place, and the sun is what lifted it. Sunlight warms the sea, the water rises as vapor, and it falls on the hills as rain. So the light from a dam is sunlight that took the long way around.