The Greenhouse has a 4’x4′ grow bed and two 4’x6′ grow beds. So it made sense to have enough power to run all the beds from a single solar panel and battery. We placed the bed above a nutrient tank. The bed was filled with pea-gravel. We used the 4 pump panel. The pumps were all wired to the controller. We placed a solar panel outside on a stand. We used 12 gage wire to connect the solar panel to the controller and the battery to the controller. The fill tubes have a 3″ anchor disk. We buried the fill tubes in the 4 corners of the grow bed. The 4 pump panel was placed in the nutrient tank. The bed sensor is buried near the surface of the grow bed. The nutrient sensor is submerged in the nutrient tank. The bed fills every 3 and a 1/2 hours. This is frequent enough to keep the roots wet. In between flood cycles the bed draws in air to the roots. After a few weeks an algae culture grows under the surface. This algae helps the roots retain moisture. Plants can be seedlings or seeds can be directly sprinkled in the pebbles. The success of germination period depends a lot on warmth and sun. We had a problem with squirrels eating the seedlings.The solar panel is 12V 100 watt and was selected to power 4 beds. The battery is a 50 amp/hour lead acid gel cell. Most car batteries will work fine. The controller is both a solar charge regulator and bed flood timer.
The results are still in process. But the automatic watering is a big relief to the greenhouse owner.