I would guess that it’s a solar-powered well. I’m definitely no expert in wells, but I know they require a pump to bring the water up from deep underground to the surface. The solar panel may provide power to the pump that brings the water to the tank.

Whatever you do, please do not remove the blue thingy without wrapping a towel around your head, and make sure it covers your eyes completely.

Tubing in the desert 😅