Here’s a brilliantly simple Instructable on using the sun as your pump for a hydroponics system.
According to the Instructable, clouds passing in front of the sun creates enough change in light to make the pump run. Has anyone seen scaled-up versions of this? Seems like it could be a great way to create some water pressure for harvested rainwater…
My understanding is most plants prefer cool/cold ground and water. If you read up on hydroponics, regulating the water temperature is a very important element.