automated solar powered irrigation

ksJoe

5 year old buck +
I've been working on this for a last couple months and it seems to be working well now. We planted 50 pines and I don't want to spend the summer hauling water to them. Since there is surface water available nearby, I decided to automate it.

I went with a slow flow rate because a higher flow rate would require everything be much bigger and much more expensive (pipe, pump, solar power, water source). But feeding drippers for hours doesn't take much, and soaks in better.

We built it incrementally testing each step as we went so we didn't end up with a large pile of parts that wouldn't work.

Step 1: I ran 600 feet of 1/2" irrigation tubing, with 1/4" tubing dropping down to each tree with a 1 gallon per hour dripper at each tree. We attached the 1/2" tubing to the top of the cages to keep it out of reach of the rodents.

Step 2: Before buying more, I connected pumps we had on hand to confirm the pipe and drippers can work with an adequate pump. The 1/5 hp submersible pump didn't supply enough head to water the highest trees. A 1" gas powered pump ran it fine, but it was choked back to around 1 gallon per minute.
Lessons learned:
- the 1/2" pipe can carry plenty of water for these drippers
- the pressure compensating drippers seem to compensate for the the pressure differnece from 15 feet of elevation change from one end to the other.
- the pump needs to be able to put out some pressure - a submerssible designed for minimal lift and and negligible pressure won't work.

Step 3: I bought a 12v diaphram pump and confirmed it is capable of supplying the needed pressure. I went with one rated for 3 gpm (at 0 head) or 40 PSI (at 0 flow). Choking it back to 1gpm restricts it enough that it builds enough pressure to work well. Before buying more, I connected it to the 12v output of my generator to make sure this pump is adeqate.

Step 4: I bought a solar panel, charge controller, timer, and battery. These are more than adequate for the pump, but I plan on using this power source for more stuff over time. At this point, I permanently mounted the pump (near the water source, on a board sheltered with a bucket), and set up the solar components in a steel tool box.

The pump claims its safe to run dry, and has a 4 year warranty. It has lots of reviews on Amazon, so I think that means I'll have a running pump for 4 years. If it fails before then, I'll exchange it. If it fails at 4 years and a day, I'll happily buy another.

The current problem we have is rodents chewing the drippers off to get water. I should have put the drippers at the top of the 1/4" tubing rather than the bottom, but we'll get them moved as they get chewed off. I'll also probably get some rodent repellent. Other than this, it's working well. The timer is set to run a few hours during the sunny part of the day. Both the charge controller and the battery's BMS have low voltage cutoff, so if it gets too cloudy it just won't run.

Parts list:
- panel
- charge controller (overkill for this, but I can add panels)
- battery (no longer listed on amazon, but its a 12AH LiFePO4 Weize battery with low temp protection for $70)
- timer
- pump
- 1/2 tubing
- 1/4 tubing and misc. connectors (it was cheaper when I got, and was the cheapest way to get 250' of 1/4' tubing at the time)
- drippers
- 1/4 connectors to tap the 1/2 line for 1/4" (should not have got these, should have used the drippers to tap the line)
- misc. wire, connectors, etc.


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A few updates & things we've learned so far:
- That 3 gpm/40psi pump was a bit small. I replaced it with a 6gpm/70psi pump and it does much better at maintaining pressure at the far end of the line.
- From now on, I'll only buy drippers like the one shown in the photo above. Note the cap on it that turns. When they plug, just give it a turn, and its good to go again.
- The drippers should be installed a foot or so from the main line, with another 2-3 feet of line going down to the tree. That makes them easily accessible for unclogging. Don't use drippers to tap the main line because if you need to replace it, pulling it out will make the hole in the main line too big to seal on the replacement.
- A month ago rabbits started eating the trees off above the white plastic mesh. We got hardware cloth and made 12" diameter 24" tall hardware cloth cages to go inside the fence cages.
- I expect the hardware cloth to also end the issues of the rabbits chewing the 1/4" drip line to get at the water. The drip line will enter the hardware cloth cage above the rabbit's maximum reach.

We're at about a 20% fatality rate (in extreme drought). We'll plant more trees and expand the system next year.

I pulled the pump for the winter, so its done until next year.
 
Interesting…
I may have to do something similar for when I plant fruit trees out at my parent’s place. The municipal water is about 1800 feet from where I plan to plant. But there’s a pond about 400 feet away…


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I highly recommend it. I've spent far less time messing around with this than I would have spent watering the trees this year. Once the trees get established, I expect this will continue to make them grow faster because I'll water them as much as they want, rather than as much as I have time for. I'll leave the system until the trees no longer benefit from it. Or maybe I'll just shift it over 15 feet and start another row of trees.
 
I've been contemplating how to do drip irrigation on a pumpkin path around my blinds. I was thinking a 275gal tote as a water reservoir. I know nothing about doing drip, I was wondering if you could do by gravity. Haven't started looking into it yet.
 
I've been contemplating how to do drip irrigation on a pumpkin path around my blinds. I was thinking a 275gal tote as a water reservoir. I know nothing about doing drip, I was wondering if you could do by gravity. Haven't started looking into it yet.

There are some battery powered garden hose timers that specifically say they will operate with low pressure/gravity feed. We were intending to go that route on some apple trees before the neighbor's pesticie spraying killed them. Drippers may not let any water through without pressure, but 1/4" tubing will be low flow if you just leave it open.
 
 
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