Autonomous PVC Hydroponic Garden From an Old A-Frame Metal Swing

The design of this Hydroponic Garden is very simple. The water is pumped up from the tank into the channels made of PVC pipes, then water is returned to the tank. The plants placed in the holes are provided with a growth substrate dissolved in the water.

The advantage of this project is that thanks to the use of solar panels, battery and controller, it can work autonomously. So, you can set up this Autonomous PVC Hydroponic Garden wherever you want.

You don't need soil, you don't need to constantly water the plants, you don't even need electricity!

Thanks to the strong A-frame of a metal swing that was used and the durable properties of the PVC pipes (according to some data PVC piping lasts 40-80 years), this construction is very strong, and also very easy to assemble.

an old A-frame outdoor metal swing for kids,

4 in. PVC sewer and drain straight pipe, you will need 4 pipes a little longer than the A-frame length of your future PVC hydroponic garden,

4 in. PVC sewer and drain flat end caps, 8 pieces,

1 in. PVC sewer and drain straight pipe and PVC 90-degree elbow for siphon (optional),

metal U channel profile, you will need 3 pieces equal to the width of the A-frame,

metal aluminum angle bars, you will need 2 small pieces for the filtration compartment in the reservoir (optional),

plastic hydroponic planting mesh net pots baskets / cups with a diameter slightly smaller than the diameter of the pipes, quantity depends on the length of your A-frame of your future PVC hydroponic garden,

tubing to connect PVC pipes,

rubber tubing to connect the pump,

hose adapters to connect tubing (hoses),

a sturdy reservoir with a big enough volume to keep the pump underwater,

a reservoir for siphon,

a storage tote container with lid to store the battery,

PVC glue,

saw for metal or dremel with cutting kit,

cordless drill and drill bit set for metal,

hole saw bit,

screwdriver set,

stainless steel screws,

a piece of metal mesh for filtration protection (optional),

scissors for metal,

strong wire for fixing pipes on the A-frame,

flexible wire for fixing metal mesh,

thread seal tape,

clay beads or hydroton,

plant growth nutrient solutions.

For the electrical part:

1 mini Submersible Water Pump 12V 18W,

2 solar panels, 50Wc, 12V,

1 controller 10A (or 20A to be safe),

1 12V battery with a charge capacity of at least 36000mAh (preferable 3 times that),

wires,

soldering iron,

solder.

The old A-frame outdoor metal swing for kids will be the frame of this PVC Hydroponic Garden. Cut the A-frame metal swing to the height you need.

Now you need to make the crossbars on which the pipes will lie (to support the pipes - the water channels).

Measure and mark on the A-frame the height that the pipes will be at so that several pipes will fit inside the A-frame at a distance sufficient to grow your plants - 2 in this project. The pipes should be placed at a slight angle to allow the water to flow from the high end to the low end by gravity.

Measure the width of the A-frame at your chosen height. Add two PVC pipe diameters to this width and cut 3 pieces of metal U-profile to that length. As a result, you will be able to lay two pipes inside the frame and two pipes on the sides outside the frame (one pipe on each side). Make sure that the measurements taken are correct.

Drill holes in the A-frame at the height you marked and in the appropriate places on the metal U-profile pieces.

Screw the pieces of metal U-profile to the A-frame.

Prepare 4 pipes a little longer than the A-frame: cut with a saw or if you have pieces, then connect them by gluing.

Make a marking at what distance there will be holes for plants in the pipes. The distance between the holes and, accordingly, the number of holes, as well as the size of the holes, depend on the space, types of plants, flowers, or fruits you want to grow. I think spacing of approximately 6 inches will be optimal. Make sure that the measurements taken are correct.

To maximize space between plants you can alternate the cutting so when the channels were placed, the holes were in checkerboard pattern.

Using a hole saw, cut holes in the PVC pipes.

Close the ends of the pipes with caps.

There are different types and methods of hydroponic systems. This project shows 2 methods. In the PVC hydroponic system (NFT) water is circulating from the container to the tube (with the pump) then flowing down back to the container, so, the box with the siphon is not needed, it's just another method (this why this step is optional). Siphon is used to make a tide system that starts and stops automatically (in a box with a siphon).

To form U siphon connect and glue 1 in. pipes:

straight up using a straight pipe,

180° curve using 2 times 90-degree elbow pipes,

straight down using a straight pipe,

90° curve using 2 times 90-degree elbow pipe,

then through the box wall,

then tube for evacuation.

Making a reverse U just that cut the intake part in 45° roughly to avoid suction (like / ).

Put the pipes on the frame: 2 inside the frame + 2 on the sides (one on each side).

Fix the pipes with wire so that the holes are at the top.

Using tubing connect the pipes on both sides:

on one side, connect the second and third pipes, add hoses to the first and fourth pipes (black hose in the photo),

on the other side, connect the first pipe to the second pipe, the third pipe to the fourth (transparent hose in the photo). Make sure any joints made are leak proof.

There are 4 elements to take into account for the electrical part:

1. A solar panel is defined with its tension (U) and crest power (Wc). The crest power is a theoretical value, and not the real power the solar panel is able to provide. the real power depends on the quantity of sun received by the solar panel and some other variables (temperature, sun light angle, …). But we can consider the power output of a solar panel with a proper orientation (south) and angle (45°) should give roughly 80% of the crest power.
2. A battery has a charge capacity usually expressed in ampere per hour (or Ah, or eventually mAh) and a usage tension (U, in Volts).
3. A pump has a usage tension (U, in Volts) and a max power (W).
4. In between all those, if you don’t want to burn your battery, you need a charge controller, who has a working tension (in Volts), and a max intensity (in Amperes).

As rule you need a battery that provides the same tension as the controller, the solar panels and the pump. It’s not difficult to find 12V pumps, car or boat batteries are usually 12V, the controllers are 12V and there are plenty of solar panels providing 12V (or more).

So, 12V will be your common point for all those equipment.

A reminder: power = tension times intensity (P = U * I).

As you have the nominal power of your pump (18W for an example), you can determine the intensity used by the pump using the previous formula: 18 = 12 * x . So, x = 18/12 = 1.5A

That pump, when running at nominal power, will need 1.5A.

Now you know you have the intensity your pump needs. You can now determine the size of your battery: it’s defined with tension (we fixed that value already) and load capacity in mAh or in Ah. That value XmAh means “this battery can provide XmA over 1h before being empty”.

You want to be sure your system is going to run all day and all night (or maybe even longer, just to be safe, let’s say 3 days, or 76h). Your battery charge capacity has to be: 76h * 1.5A = 114Ah, or 114000mAh. That’s a rather big battery, but we took 3 days without reload, so, you can take a less large battery, as long as it’s more than what your pump would use in 24h (so 36000mAh).

You now have a battery and a pump that work together, and the pump will work for some time when connected before stopping. It’s time to reload it. Here come the controller and the solar panel.

The solar panels never give a clean, nice looking current. There are clouds, there are sunsets, sunrises, a cat or a bird is sitting over it, etc., so, its not always what you expect and the battery wouldn’t be happy at all with that. There is another problem, slightly more annoying: a battery has a max load. If you go above it, you might make it explode, spill chemicals, take fire, well, plenty of nasty things you certainly don’t want to happen.

So you use a controller that will load the battery when there is light, and that will stop loading it when it’s full. Security stuff … good boy. They are usually defined with a maximum intensity they can handle (10A, 20A, 30A).

But it can wait a little before we decide which to take. the only difference is the price.

Your solar panel indications gives you its crest power. Nasty experimental value you will never reach (unless you place it perfectly clean, facing the sun, on a fresh and clear day, with perfect conditions, so… never). A usual estimation is 80%, but it can vary with your region. We’ll make the calculation with 80%, that’s easier.

So, let’s say we have a solar panel that is declared at 50Wc and 12V.

I estimate I’ll get from it something like 50*0.8 = 40W of electricity.

Knowing it’s producing 12V of tension, and using that previous formula, you then get 3.3A per hour (note this value, it’s important).

Sun being sun, it moves, so, that good solar panel will work only for, let’s say, 12h in summer.

So, your solar panel with produce a huge 40A over a perfectly sunny day. Over a while day, that’s a production of 1.6Ah.

Do you remember the intensity usage of the pump we calculated earlier? 1.5Ah.

This solar panel produces 1.6Ah over 24h at best, with 12h of sunshine.

So, basically, the whole system is independent if you get only sunny days with a temperature around 20°C, during a cloudless summer day.

Let’s play safe, and let’s use 2 solar panels of that type, for when it rains, when it’s spring, etc. (using 2 panels requires 5.5h of sun to fully reload a battery strong enough to make the pump run for 24h).

Your solar panels will produce 6.6A at best, which is far enough, and it also gives you the maximum intensity the controller will have to manage. You can take a 10A one (or a 20A if you want to be quiet, the difference in prices is not huge).

So, your system should be independent with:

• a pump 12V 18W;
• two solar panels, 50Wc, 12V;
• a controller 10A (or 20A to be safe);
• a 12V battery with a charge capacity of at least 36000mAh (preferable 3 times that).

The connection of the solar panel, pump and the battery with controller is very simple - see the photo diagram of the connection. Solder the wires according to the diagram.

Place the pump in the water tank and connect it with a tube to the first pipe. The pipes are then connected to each other. Dip the hose from the last pipe into a tank of water (a tank with a siphon if you made it).

This step is needed if you made the step 3.

So that the water flowing from the pipe system does not clog the siphon with particles of roots, you need to install a filtration chamber. 

Using aluminum bars and pop rivets make a frame.

Sew the mesh to the frame using wire.

Fill the tank and run water through the system to test your PVC pipe system. Make sure all the parts are running smoothly. 

Add your plants or seeds into every net pot filling with clay beads, then insert every net pot into the system. Be sure the roots are touching the stream of water in the pipe. 

Add nutrients, plug in your pump and watch your plants grow!