Neighborhood Irrigation System

[Crazyfrenchbiker]

Hi everyone,

I'm working with my HOA to modernize some of the systems in the neighborhood and one of those systems include the lawn sprinklers found at our park. Currently, we are paying the utilities a monthly service charge ($35), and using about 50 cents of power, per month. During the summer, this is only a few dollars, and likely only a handful of KWH.

I'm exploring alternatives to replace this service charge by integrating solar power at our controller station. The irrigation controller we're using is a Rainbird ESP-TM2, which operates on a 110V input. While running, it draws around 1 amp (though not confirmed), and at idle, it's just a few milliamps. I wish it ran on DC, which would simplify matters, but it was recently replaced, so I doubt we can swap it out again.

I have a spare 100W solar panel from another project that I'm contemplating using. I plan to mount it via a pole attachment where the irrigation controller is situated. Given our cold climate, I'm also considering employing a marine deep cycle batter so I don't have to worry about heated / limiting charge in colder temps.

The primary challenge lies in selecting an appropriate inverter/charger combination. Price is a crucial factor, and I'm aiming to keep the combo under $300. Any recommendations on this front would be greatly appreciated.

Here's what I thought could be an option

• Victron Sun Inverter 12/250
  • Positive, one combined unit
  • Negative - It would require some kind of transformer to convert 220 to 110.
  • Consideration - Limited to 1 solar panel, as it seems like it is limited to 25V / 15A (not that
• Victron Energy Phoenix 375VA + Victron Energy SmartSolar MPPT 100V 15 amp
  • Positive - Extra solar capacity
  • Positive - Pure Sine Wave
  • Negative - 2 Units and extra cost
• Battery Tender 200-Watt Power Inverter + Victron Energy SmartSolar MPPT 100V 15 amp
  • Positive - Extra solar capacity
  • Positive - Cheap inverter / easy replacements
  • Negative - Modified Sine Wave

I appreciate any input anyone can offer.

Thanks!
Gil

 

[wpns]

Do you even need this to work when temperatures approach freezing?

 

[Crazyfrenchbiker]

Do you even need this to work when temperatures approach freezing?

No, not at all. The system does get winterized, so there could be a "kill switch" on the battery or something.

 

[740GLE]

Do you even need this to work when temperatures approach freezing?

Community ice rink

 

[seneysolar]

What are specs on your 100W panel? Might be worth looking at a PWM charger.

Otherwise Victron 75/15 ($70) should work on most single panel applications.

Id consider an AGM or Sealed battery - as nobody is likely to service the electrolyte levels?
Just my personal opinion - I hate the 12V "marine deep cycles". They seem to be lacking in every department.

If your draw is really that low you can get by with a 300W inverter, but Id consider the Victron Phoenix 500 ($150) These draw about 0.5 amp idle consumption.

 

[TMON]

Rainbird has a 9 volt, battery operated controller (ESP-9V) that may be an option for you. The TM-2 controller provides a 24V output that energizes the solenoid that opens the control valve. You would need to replace all of the 24 volt solenoids with 9 volt DC latching solenoids to operate with the ESP-9V controller.
You're going to need to determine how many control valves are on the system (max.12 on a TM-2) and the manufacturer and model number of each valve. Then you would need to research the correct replacement 9 volt DC latching solenoids to properly fit and operate the existing control valves. Ideally everything is Rainbird but you're probably not that lucky.
Also the maximum number of stations (valves) on the ESP-9V is (6).
So if you have (6) or less valves and you can identify the valves, you may consider this option. You then replace two 9V batteries every 4 to 6 months.
No solar involved.

 

[seneysolar]

No solar involved.

No. The answer is always more solar!

 

[chrisski]

Rainbird has a 9 volt, battery operated controller (ESP-9V) that may be an option for you. The TM-2 controller provides a 24V output that energizes the solenoid that opens the control valve. You would need to replace all of the 24 volt solenoids with 9 volt DC latching solenoids to operate with the ESP-9V controller.
You're going to need to determine how many control valves are on the system (max.12 on a TM-2) and the manufacturer and model number of each valve. Then you would need to research the correct replacement 9 volt DC latching solenoids to properly fit and operate the existing control valves. Ideally everything is Rainbird but you're probably not that lucky.
Also the maximum number of stations (valves) on the ESP-9V is (6).
So if you have (6) or less valves and you can identify the valves, you may consider this option. You then replace two 9V batteries every 4 to 6 months.
No solar involved.

I like this 9V battery option which is under your budget.

At the cost of about $.20 per kWh, I’m assuming your power draw is about 100 wH per day, but I really recommend you put a killawatt meter on a day during its usage.

With the solar option there is always what happens when you have a week of cloudy weather and can’t fill the batteries up, so how do you power the irrigation or bring it back to life? I’d look at what the cost to replace the batteries. I would not be surprised if you replaced lead acid batteries in two years.

 

[Solar Guppy]

This isn't in the best interests of the HOA to do anything. Solar isn't a build and forget and cost wise, it would at best take years to recover, worst it breaks an no one has a clue what it is.

I've served on the board on two HOA's as treasure ( 10 years ) and I would never consider this appropriate for the community. I'm also about as pro-solar as they come, but that doesn't mean you do something like this just because you can. I suspect I'll get some neagative feed back on this one

 

[seneysolar]

This isn't in the best interests of the HOA to do anything. Solar isn't a build and forget and cost wise, it would at best take years to recover, worst it breaks an no one has a clue what it is.

I've served on the board on two HOA's as treasure ( 10 years ) and I would never consider this appropriate for the community. I'm also about as pro-solar as they come, but that doesn't mean you do something like this just because you can. I suspect I'll get some neagative feed back on this one

His budget is $300, probably end up around $400

But they are spending $35/month = $ 420/ year

Sounds like a decent ROI to me.

If they get a week of clouds, probably not as big of need to water anyways.

 

[Crazyfrenchbiker]

What are specs on your 100W panel? Might be worth looking at a PWM charger.

Otherwise Victron 75/15 ($70) should work on most single panel applications.

Id consider an AGM or Sealed battery - as nobody is likely to service the electrolyte levels?
Just my personal opinion - I hate the 12V "marine deep cycles". They seem to be lacking in every department.

If your draw is really that low you can get by with a 300W inverter, but Id consider the Victron Phoenix 500 ($150) These draw about 0.5 amp idle consumption.

It did come with a PWM controller originally, but I have since repurposed that for another project. Not a bad option and you're right, I definitely want a sealed battery of some kind.

Maximum Power at STC: 100W
Open-Circuit Voltage (Voc): 24.3V
Short-Circuit Current (Isc): 5.21A
Optimum Operating Voltage (Vmp): 20.4V
Optimum Operating Current (Imp): 4.91A
Maximum System Voltage: 600V DC

Rainbird has a 9 volt, battery operated controller (ESP-9V) that may be an option for you. The TM-2 controller provides a 24V output that energizes the solenoid that opens the control valve. You would need to replace all of the 24 volt solenoids with 9 volt DC latching solenoids to operate with the ESP-9V controller.
You're going to need to determine how many control valves are on the system (max.12 on a TM-2) and the manufacturer and model number of each valve. Then you would need to research the correct replacement 9 volt DC latching solenoids to properly fit and operate the existing control valves. Ideally everything is Rainbird but you're probably not that lucky.
Also the maximum number of stations (valves) on the ESP-9V is (6).
So if you have (6) or less valves and you can identify the valves, you may consider this option. You then replace two 9V batteries every 4 to 6 months.
No solar involved.

This isn't a bad idea, despite preferring not to replace the controller. I will check tomorrow what type of valves they are, and how many.

This isn't in the best interests of the HOA to do anything. Solar isn't a build and forget and cost wise, it would at best take years to recover, worst it breaks an no one has a clue what it is.

I've served on the board on two HOA's as treasure ( 10 years ) and I would never consider this appropriate for the community. I'm also about as pro-solar as they come, but that doesn't mean you do something like this just because you can. I suspect I'll get some neagative feed back on this one

I mean, I explained the costs in my post. If I can build this for <$300, the system is going to be showing a positive ROI in 8.5 months. Even if it ALL broke the every year, we'd still be money ahead. There are plenty of solar applications similar to this on a commercial scale that I see all the time in our rural areas, maybe it simply isn't as popular for you. We also have entryway lights on our monuments that will be replaced with solar counterparts as part of the whole effort, saving hundreds of dollars in services charges to our association per month.

 

[Solar Guppy]

.

 

[Quattrohead]

if the solar fails and someone is hurt on the common property, you have now exposed the HOA to unlimited costs to defend. Also there is fire protentional to consider with failures.

You gone all woke on us

 

[seneysolar]

This isn't much different than solar operated gate openers. Ive sold some to farmers and the local airport for the same reason, monthly service charges. The smaller the system, the faster ROI and the safer it becomes. The airport buys a new battery every year for no reason other than precaution and still saves money.

 

[Crazyfrenchbiker]

This isn't much different than solar operated gate openers. Ive sold some to farmers and the local airport for the same reason, monthly service charges. The smaller the system, the faster ROI and the safer it becomes. The airport buys a new battery every year for no reason other than precaution and still saves money.

That's exactly the kind of system we are thinking about. Thanks for your experience, that is much appreciated.

 

[BigDoug]

I mean, I explained the costs in my post. If I can build this for <$300, the system is going to be showing a positive ROI in 8.5 months. Even if it ALL broke the every year, we'd still be money ahead. There are plenty of solar applications similar to this on a commercial scale that I see all the time in our rural areas, maybe it simply isn't as popular for you. We also have entryway lights on our monuments that will be replaced with solar counterparts as part of the whole effort, saving hundreds of dollars in services charges to our association per month.

Sure, that works IF someone is willing to fix/replace/work on the system for free. Right now that seems to be you. But what if you move? What if the HOA does something that puts you in a position to tell them they suck and you aren't helping them anymore? Then the costs of this goes up.

Maybe the savings still works. But you do seem to not be accounting for that part of the math in the breakdown.