Getting off the grid

Since hydroponics run on power for the water pump, and the air pump, if you want to go further close to the real deal, you could grow your food without consuming more power than a natural setup would do.
Many grower around the world have Solar Panels setup to run their pumps and control units. And being near Shenzhen where a lot of things are manufactured, gave me the opportunity to get some panels.

But we got a balcony,  not a garden or a terrace. And worse, the exposition is not full South, but more West. So I have to get the maximum yield of that sun exposure. So I selected custom made flexible panels (flexible and easy to install). After communicating with an "manufacturer"/integrator, they could provide 4 custom made panels of 15cm x 92cm. So 3 of them would fit the big length, and one the short return. Why the flexible Sunpower cells ? Because they are made for RV or Boat rooftops. So they "like" not to be oriented or angled to south or 90° angle sun rays.

 You can order these panels with front or back power connection. They are all equipped with MC4 connectors, so it's easy to daisy chain.

 4 panels will give 17.4 V. Perfect voltage for my MPPT solar charger.

Calibrating the perilstatic pump

 So I received the pumps ordered on Taobao. As many forums gave various feedback on these pumps I decided to calibrate them.

In fact, for the experience, I added a cooking scale under the receiving tank and measure the water weight... as 1cc = 1 gram, it is quite easy to measure !

I ran some tests and finally, 60s equal 30cc. Easy, eh ?

To drive the pump, it is quite easy: a single TIP120, a 1K to 3.3K resistor and a power supply. Schematics & explanation can be found here.







Using a simple diagram to drive them with the Arduino, I ran the pump for a minute and measure the amount of water that have been moved from one container to another.

Structure modifications

The first modifications were to replace the clear tube between the Trofast boxes.

Instead of a direct drop to the next bucket, I used a 15mm PVC tube with a interconnect. The interconnect has a threaded male part than goes thru the Trofast, and we screw the female part on top of it. The height of that female part is perfect as the water level is just in contact of the netpots bottom.

The bottom of each dropdown tube is glued with hotglue gun and I drilled 6 holes to make some kind of shower head. The tube is just plugged into the interconnect.

Under the dropdown tube, I now have a bell with holes to prevent clay pebble to enter the tube and get stuck at the bottom. As they are bigger than the holes, the flow was restricted and I had the installation flooding the balcony.

You need a lot of holes, and they have to be under the water level. Drill also the top of the bell otherwise the syphon effect will empty the whole bucket.

I've also added more shelves on the right side. But they are not running yet.
As the tomatoes need more heights I can now leave them on the right side and have some room for the leaves.

 After a few weeks, I had a algae invasion, all the clear aquarium tubes became coated with green and the tank turned green. So I filtered the water and removed the clear tubes.

I now use the frame PVC tube to feed the water to the top, so I added a T near the tank, with a treaded adapter and a water hose brass male plug. The aquarium pump is now feeding the system thru a 30cm soft tube and then it goes to the top in the PVC frame.