The biggest challenges in designing my hydroponic planting system is how to get power to the water pump. I don't have electrical socket outside home, so I need to drill a hole through the wall, and run a long extension cable to power standard aquarium pump that most hydroponic system use.
Unwilling to drill a hole and run long untidy cable, I research and build a solar powered water pump system. My requirement is that the system need to be:
- Compact due to limited space available in my patio
- Reliable to be left unattended for a few days, just in case we go on holiday.
Considering both point above, it is important that the system use less component compared to traditional solar power system. To eliminate the need for inverter, I use a DC pump. And to eliminate the need for battery, I'm using DC Converter instead of traditional solar panel controller. The system will shutdown when the sun goes down, thus it is suitable for Deep Flow Technique Hydroponic system
Besides, plant need to live from the sun, not the power grid, right?Watch the video (Subtitle in Bahasa Indonesia), and read on for the instruction.
Step 1: The Solar Panel
The selection of Solar Panel to be used will depends on power required by the pump, plus some margin to cover for cloudy sky and power loss. A 10 watt solar panel should be sufficient to run 4.8 watt pump, although I would recommend using 20 watt (4 times of power). I'm using a 50 watt solar panel, a bit overkill. But I'm planning to add more system to the solar panel, such as Arduino as the controller for hydroponic garden.
Our roof is not designed to hold Solar Panel, and finding a way to mount it pose another challenge. The mounting is made from leftover steel beam that is used as roof frame. Using saw and pliers, the steel beam is divided and molded into 2 C-shape and 2 S-shape. The S-shapes are used to fix the panel on the concrete wall on the roof, and the C-shapes are used to support the opposite end of the solar panel.
The reason of choosing roof instead of steel pole to mount the solar panel is simplicity. It is tilted slightly to the east so that the system will start early in the morning after night long of shutdown. As I'm living in the equator, it doesn't matter if the solar panel face north or south, nor that it require regular adjustment.
A note on cabling. Typical solar panel come with MC-4 connector. It is water proof, and weather proof connector that is used to connect the panel to the cable that brings the power to the controller/converter. It can be bought in solar power supply shop.
As seen in the picture, during the day, the solar power generate 19 Volts DC electricity.
Step 2: The DC-DC Converter
The 19 Volts that the solar power generated will blow the pump if connected directly. There are two options to reduce it to 12 Volts that the pump can accept without blowing, using Solar Charge Controller or DC-DC Converter.
Solar charge controller, in addition to converting the solar panel output to 12 Volts, also able to charge 12 Volts battery. The charge controller will also switch the power from solar panel to battery at night to keep the quipment running. However, most solar charge controller available in the market require a battery to be attached to operate properly. This makes it less suitable for my design, as I don't need the battery to run the pump at night.
Therefore, for my project, I'm using a DC-DC converter, based on LM2576 regulator. The regulator are able to accept input up to 30 Volts, and stabilize the output to 12 Volts with maximum load of 3 Amperes. Fortunately I have a ready made kit sold at a local hardware store. Just in case you prefer to build it, the component list is available in the LM2576 datasheet. Or you can also use another 12 Volts regulator kit that is available, such as LM7812. Just make sure that the IC can handle the current that the equipment need.
The whole circuit is then put inside a plastic container to make it waterproof.
Step 3: The Pump
Finally, the output of DC-DC Converter is used to power the 12 Volt 4.8 Watt Water Pump. Eventhough the power look small, the pump is quite powerful, especially around 12pm, the the sun provide maximum output.
Please watch the video to see the output of the pump. Enjoy....