Solar Pump Controller

Background

After terracing a portion of my property near our lake, I quickly realized the inefficiency of carry sprinkling cans of water to the plants. The wheels started to spin. After some preliminary research, I thought I had found a solution in the Irrigatia SOL-C24. However, after one season the included irrigation hose and drippers became clogged. Attempting to modify the unit with new, larger hoses made the problem worse. Time to build my own solution!

Since I already had a 900Mhz wireless network, courtesy of LowPowerLab's super awesome Moteino Gateway, building a solar pump around a Moteino was the logical choice.

Parts List

Basically I wired together a solar panel, solar charge controller, submersible pump, battery, and moteino. Well, it wasn't quite that simple.

Here is a summary of all the parts needed to assemble the pump controller. Mounting hardware may very depending how you choose to mount the enclosure the contains the electronics.

• Moteino
• Small Solar Charge Controller
• 10 Watt, 12v Solar Panel
• 12v, 1A, submersible pump
• IP65 outdoor enclosure
• PS1270 12v, 7AH standard alarm battery
• IRLB8721 N-Channel MOSFET
• ALS-PT19 Analog Light Sensor
• Two Adafruit quarter sized PCB
• Three PC817 Optocouplers
• 1N4001 Diode
• Two 0.1 µF capacitors
• LED
• Various resistors – see circuit diagram
• Various mounting hardware and accessories such as:
  • 1/2” Tubing and irrigation fittings to suit
  • Outdoor rated 18/2
  • Garden fence post
  • Z brackets
  • Flat aluminum bar from local hardware store
  • Thin piece of plastic or wood for enclosure backplane
  • nylon M3 standoffs
  • screws and bolts
  • cable glands
  • terminal strip
  • pump inlet strainer

Not Discussed

For brevity, I am going to skip over much of the physical assembly. I am also not going to cover assembly of the irrigation tubing. If there is anything you would like to know more about, feel free to ask in the comments below.

Click to Enlarge

Solar Pump Circuit

Electrically, the control circuit can be broken into the following functions:

• Moteino (not shown)
• Charge Controller
• Battery Monitor
• Ambient Light Monitor
• Trouble Monitor
• Pump Running Monitor
• MOSFET Switch

Prerequisites

The solar pump controller communicates with a Raspberry Pi, running the Moteino Gateway. The gateway creates the 900MHz network and provides the Web UI to monitor and control the various wireless devices.

Instructions

1. Assemble the circuit shown in the diagram above.
2. Load this Solar Pump arduino sketch into the Moteino. Instructions for programming a Moteino are here.
3. Create the Solar Pump config on the Moteino Gateway
1. Copy solarpump.js to the userMetrics folder on the Raspberry Pi gateway
2. Copy icon_solar_pump.png to the www/images folder on the Raspberry Pi gateway
3. Restart the Moteino Gateway service
4. Mount the equipment inside the cabinet
5. Mount the cabinet to its permanent location
6. Attach the battery
1. CAUTION: The charge controller stated the battery must be attached first, prior to attaching the solar panel.
7. Wire the pump and the solar panel

Moteino Gateway UI

Solar Pump Controller on the Moteino Gateway UI
Click To Enlarge

Once the Solar Pump Controller is powered up, it will automatically populate on the Moteino Gateway Dashboard. Click on the newly populated Moteino then set the Type from the drop-down to Solar Pump Controller and give it friendly name. Once you set the controller type, several buttons will appear at the bottom to allow you to control the pump.

Button Definitions:

• Off/On - Toggling this off prevents the schedule from running.
• Refresh - This forces the Moteino to immediately report its status
• Run - This immediately turns the pump on (for the scheduled duration)
• Stop - This immediately turns the pump off (until the next scheduled start time)
• Schedule Up - Increases the time between running by 1 hour
• Schedule Down - Decreases the time between running by 1 hour
• Duration Up - Increases the pump runtime duration by 5 minutes
• Duration Down - Decreases the pump runtime duration by 5 minutes

Finished Product

Sample photos of the finished product. Click to Enlarge.

Control Circuitry + Battery

Control Cabinet and Solar Panel Mounted

All Finished!