Solar for sprinkler irrigation controller

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I've got a new site on my land that we're setting up for gardens and we want to put the watering on automatic valves with a multizone timer controller.

There's a ton of rock and other plantings between the garden site and the nearest power, plus it's about 150', so I'm considering using a solar panel system to run the controller right at the garden site to avoid trenching for power and all that (water is at the site already from a different direction).

The sprinkler controller I bought claims to use 0.2A @ 120V (presumably maximum; that's what 24W?). I can't find any reference to how much current a typical 24VAC sprinkler solenoid actually draws while in use, and this information would be good to have in sizing the solar setup.

I see mighty mule sells a 10W setup to run a gate opener (for "heavy gates opened many times a day") which is surprising to me - I would've thought that you'd need more than 10W for that, and I'm thinking that running a few solenoids would presumably not pull as much power as a motor?

I found this: https://www.amazon.com/Crystalline-Intelligent-Controller-Perfect-Maintainer/dp/B08RZ1Y7CJ/
(50W panel + charge controller); I have an older battery that still has a decent charge (just not enough to start a motorcycle), and can get a small inverter for $25, and this is all less than it would cost to run 12-wire sprinkler wire from the alternate location if I put the controller in the shop where there's power (and don't put the sprinkler wire in the ground... i don't like this idea you can see).

So questions:
1) how much power does a sprinkler controller running a few solenoids need?
2) site will get 5-6 hours of sun when it's needed (late spring through summer). Is 50w overkill?
3) will this charge a LifePO4 (shorai lithium) battery or should I use something else?

 

[npalen]

There are sprinkler controllers "out there" that are battery powered by, for example, three or four AA batteries with option to add a proprietary solar panel.
The battery powered controllers output 24 volts DC rather than the normal AC and DC latching solenoids retrofit to the valves so they only draw power when turning on the valve.
Lots of good info on sprinklerwarehouse.com

Available in twelve station also:

Hunter XC 6 Station Indoor/Outdoor Plastic Hybrid Battery Operated Controller | XCH600

Hunter XC 6 Station Indoor/Outdoor Plastic Hybrid Battery Operated Controller | XCH600 | Controller-Timers

www.sprinklerwarehouse.com

Solar panel:

Hunter SPXCH Solar Panel Kit for XC Hybrid

Hunter SPXCH Solar Panel Kit for XC Hybrid | Sprinkler System Sensors From Sprinkler Warehouse | Shop Online Today.

www.sprinklerwarehouse.com

 

[plowhog]

I also have piped irrigation water in areas with no power. And no sprinkler control wire either.

I've used the Hunter Node battery irrigation timers (with Hunter valves) and they have worked well. They run on an 9v battery, and if you are worried about ever losing power you can snap in a second 9v battery as well. I've run them 3-4 years now without any problem or failure.

So far, I've just used the single output Nodes. One Node, wired to one sprinkler valve, very simple. I do have a 4-station Node, but that means pulling wire and I have never got around to doing that.

If you use these, double check one thing. Mine came with 24vac solenoids to actuate the valve. I needed to change these to 12V DC solenoids.

 

[plowhog]

Keep in mind if you are adding a possible fire hazard. LifePO4 is about as low risk as you get with lithium batteries. Other variants, not so much. I had a lithium battery start a wildfire a few years ago so I'm leery of those being unattended.

a LifePO4 (shorai lithium) battery or should I use something else?

 

[ning]

Keep in mind if you are adding a possible fire hazard. LifePO4 is about as low risk as you get with lithium batteries. Other variants, not so much. I had a lithium battery start a wildfire a few years ago so I'm leery of those being unattended.

Good to know, thanks.
I may have another older car battery (lead acid) that may have enough life for this application.

Another advantage as I see it of having the solar/battery/inverter setup is being able to plug in a phone to the inverter for music, though that's quite secondary.

I'm still curious about the actual 24vac solenoid power draw.

 

[npalen]

Checked one of my Hunter valve solenoids and its showing 376 milliamps on 24 VAC while operating.

 

[npalen]

Checked one of my Hunter valve solenoids and its showing 376 milliamps on 24 VAC while operating.

 

[npalen]

Checked one of my Hunter valve solenoids and its showing 376 milliamps on 24 VAC while operating.

That may include the solenoid relay for the pump, however, which is rated at 125ma.

 

[npalen]

Understanding 24VAC Sprinkler Valves | OpenThings

openthings.io

Everything you wanted to know about sprinkler valve solenoids.
I believe it says about 200ma (0.2 amps) at about 3/4 of the way down the page.

 

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Understanding 24VAC Sprinkler Valves | OpenThings

openthings.io

Everything you wanted to know about sprinkler valve solenoids.
I believe it says about 200ma (0.2 amps) at about 3/4 of the way down the page.

Thanks!

I'll have to digest the pages about reactance etc but I think the main takeaway is that it takes 0.2A at 24VAC or about 5W to hold, so I can roughly guess I'm going to need about 20Wh for my purposes, and with a hypothetical 50% system efficiency my solar panel will need to provide 40Wh per day - easily done with a 10W panel, so using a 30W will provide a reasonable amount of overkill.

 

[MossRoad]

Out of curiosity, what type of valves are you operating, the size of the pipe, and how many zones?

 

[ning]

Out of curiosity, what type of valves are you operating, the size of the pipe, and how many zones?

I got a few "orbit 3 valve manifold" setups that are chained; fed from a 1" line, each valve has a ⅝" poly line running to a large raised bed garden box (the poly line is buried under chips but not in the ground as the ground is ridiculously hard and has many large rocks in it, no thanks I'm not drigging in it right now).

At each box there's a ½"-to-¼"adjustable manifold that up to eight ¼" tubing lines can be attached.

Each large planter box is set up to be a separate zone to allow for fine-tuning of run times.

It's overkill (one zone could easily water multiple boxes) but this setup will be flexible, configured up front so whatever the gardeners want to do they'll be able to with little further effort; my time is more valuable to me than a little bit of up front equipment cost.

(Btw the valves are fed from irrigation-only water, not from the house's water supply, so we don't have a need for anti-siphon valves.)

 

[MossRoad]

The reason I asked is that I have an old Orbit 4 zone battery operated timer like this below. It runs on just 2 AA batteries. I have no idea how long the battery life is because they last me all season. In the fall I remove the batteries and toss them and store the unit in a shed. I've been very happy with it. Super simple. We have all of our hanging baskets and pots (about 25), our large flower planters, our flower beds around the house, deck and pool, a sprinkler in our front yard, and our entire garden on it. Everything is drip with the exception of the front yard sprinkler. Heck, we even have the bird bath on it to keep it topped off.

Anyhow, just 2 AA batteries and no need for solar or large batteries.

Food for thought.

 

[npalen]

The reason I asked is that I have an old Orbit 4 zone battery operated timer like this below. It runs on just 2 AA batteries. I have no idea how long the battery life is because they last me all season. In the fall I remove the batteries and toss them and store the unit in a shed. I've been very happy with it. Super simple. We have all of our hanging baskets and pots (about 25), our large flower planters, our flower beds around the house, deck and pool, a sprinkler in our front yard, and our entire garden on it. Everything is drip with the exception of the front yard sprinkler. Heck, we even have the bird bath on it to keep it topped off.

Anyhow, just 2 AA batteries and no need for solar or large batteries.

Food for thought.

Are your solenoids AC or DC? Just curious.

 

[MossRoad]

Are your solenoids AC or DC? Just curious.

The solenoids are run by the same 2AA batteries that run the timer. Everything is hooked up with garden hose. 4 solenoids plus the timer run somewhere over 6 months on just those 2 AA batteries.

 

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I don't see a picture, but I think I have the same thing at another spot that was even farther from power.

I got the three 3-valve manifolds at a pretty good price (under $20/valve plus all the other easy-to-assemble parts; possibly one more with future expansion to 12 valves) and a 12-station controller for $60; $60 for the panel&charge, $20 for an inverter, and TBD for a battery (I think I can use an old battery I have) - $320 ($380 @ 12 valves). Oh, add a 4x4 to stick in the ground under the panel.

I see about $60 for a single 4-zone battery controller with one valve; I'd need 3 of these to replicate what I'm setting up right now (9 valves, up to 12 future expansion), plus another 6 valves (and connecting stuff, or two of the above 3-valve manifolds; 3 more if I expand) & 6 DC solenoids ($11 each)... but then I wouldn't need all the other stuff I'm setting up (less labor possibly). = $360 ($450 @ 12 valves)

Price-wise I think it's almost a wash, but the battery way is simpler overall, though possibly less of the "this project is fun!"

BTW I'm aware that the number of valves and zones is substantial overkill. I'm hoping to chain multiple boxes onto the same zone as the gardener figures out what she's planting where and then I can use the subseqently 'extra' valves to water yet-to-be-discovered zones.