So, I'm obviously the tardy one in the group of challengers here, but today my daughter and I will be constructing the hydroponics portion of the actual project. We've got syringes, one way check valves, linear actuators, relays, transistors, PVC piping, power supply, two high side current monitors (one for 5V draw, the other for 12V draw), and plenty of cuss words (obviously on my part) to make this a successful build. I'm planning on posting pictures later today of our progress. I am not sure if I'm going to have time to build the nutrient cooling system, as I'm pretty sure we're gonna start germinating seeds this week. My plan is to get the build done today, test out the hardware, and then spend all of next week writing the software while the seeds germinate.
Our vertical farming system utilizes 3" PVC pipe in 3 lateral, stair-stepped tiers (still clearly qualifies as a vertical farm), with a gravity fed nutrient dispensing system. The nutrient dispensing is controlled by a 1/2" latching solenoid valve, so a brief positive current opens the valve, and a brief reverse of the polarity closes the valve, this way current draw is minimized. The nutrients are aerated and returned to the nutrient reservoir via a geyser pump that we have constructed. The PH level is checked with every nutrient feeding cycle, and the system supports addition of PH up or PH down to adjust the PH level. Right now, the arduino is doing the heavy lifting with regard to controlling the linear actuators, valves, etc., but my intent is to utilize the processor provided for all of those tasks, so that the only arduino in the system is simply relegated to measuring current draw at regular intervals for the purpose of determining power consumption of the overall system.
While I am using an open frame dual output power supply to power the system, all of the components are 12VDC or 5VDC, so the system as a whole can conceivably be run completely solar. Evaluation of the power consumption profile as the system runs, should verify this.