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Designing an off-grid system to water crops

vinthewrench

vinthewrench

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I am in the process of designinga system to water some pumpkin crops. I am in Arkansas and have plenty of onobstructed sunlight during growing season. I am putting together a systerm to pump water out of a creek into a storage tank and then from there to another constant pressure pump to water the pumpkin sprinklers.

I willprobbably use a 3/4 hp self priming JET pump from DAB (https://rainharvestingsupplies.com/self-priming-jet-pump/). which could use 110/220 at 8.55/4.33 A to pump from the creek to tank and then an ESYBOX mini (https://rainharvestingsupplies.com/esybox-mini-3-on-demand-constant-pressure-variable-speed-pump/) 110/220v 9.6A/4.8A to drive the spinklers.

I have a bunch of good Silfab 500w modules around that I can use for PV, but I am trying to figure out which inverter /charger to use. I am considering the Enphase, (but as far as I understand they need power from the grid.

can someone offer a recommendation for a "reliable" inverter/charger to give me around 2KW at peak (assuming both motors end up runing at same time) .. I plan to be off-grid and without internet at tis site (although I can bluetooth or use a serial connection for monitor)


many thanks.
 
vinthewrench said:
I am in the process of designinga system to water some pumpkin crops. I am in Arkansas and have plenty of onobstructed sunlight during growing season. I am putting together a systerm to pump water out of a creek into a storage tank and then from there to another constant pressure pump to water the pumpkin sprinklers.

I willprobbably use a 3/4 hp self priming JET pump from DAB (https://rainharvestingsupplies.com/self-priming-jet-pump/). which could use 110/220 at 8.55/4.33 A to pump from the creek to tank and then an ESYBOX mini (https://rainharvestingsupplies.com/esybox-mini-3-on-demand-constant-pressure-variable-speed-pump/) 110/220v 9.6A/4.8A to drive the spinklers.

I have a bunch of good Silfab 500w modules around that I can use for PV, but I am trying to figure out which inverter /charger to use. I am considering the Enphase, (but as far as I understand they need power from the grid.

can someone offer a recommendation for a "reliable" inverter/charger to give me around 2KW at peak (assuming both motors end up runing at same time) .. I plan to be off-grid and without internet at tis site (although I can bluetooth or use a serial connection for monitor)


many thanks.
Click to expand...
Wy 120/230 volt pumps ?

Wy not use 12/24 boat pumps for drinking water.
It have 1.5bar pressure .
Some do even more .
Than you can set a battery and solar panel with wind energy.

This is how our farmers use the systeem

Link
4.7 bar pump.

Aqua King Premium 4.0 12V 15L/min

Koop Aqua King Premium 4.0 12V 15L/min makkelijk en snel online bij SailSupply.nl. Ook voor al je overige Plastimo Drinkwaterpompen. Altijd voordelig en wereldwijd geleverd.
www.sailsupply.nl www.sailsupply.nl
 
Agree with above the other factor you need to account for is the numbers you gave likely don't account for startup (inrush current) which could be greatly more than you quoted if you stick to a DC pump that won't be as much of an issue but best guess is with AC your quoted pump might have a power factor of 0.2 with no load edging you further towards a 5kw inverter. Save the money from the inverter get a DC jet pump instead and a decent charge controller it should be more reliable and have far less gremlins/things to go wrong.
 
Trying to power an induction motor like that jet pump, you need an inverter and battery able to deliver LRA for surge, about 5x running current. And it will draw constant power when operating but PV production will vary. So PV would have to be oversized.


What you want is a PV direct system, no battery, which will have a brushless DC motor (3-phase motor and variable frequency drive) having PV input. It performs MPPT to maximize power collected, pump as much as possible at any time.

Array should have multiple orientations to get morning and afternoon sun.

Solar water pumping systems

Grundfos is dedicated to pioneering the future of water technology, and our range of renewable energy powered products does just that.
product-selection.grundfos.com product-selection.grundfos.com
 
vinthewrench said:
I have a bunch of good Silfab 500w modules around that I can use for PV, but I am trying to figure out which inverter /charger to use. I am considering the Enphase, (but as far as I understand they need power from the grid.

can someone offer a recommendation for a "reliable" inverter/charger to give me around 2KW at peak (assuming both motors end up runing at same time) .. I plan to be off-grid and without internet at tis site (although I can bluetooth or use a serial connection for monitor)
Click to expand...
This seems unnecessarily complex.

I'd steer you towards a single, solar direct, pump solution. The Grundfos SQF comes to mind. You can series ~4 to 6 of those modules and a get a lot of water.

Also I'd mention that some states prohibit pumping water out of a creek. Certainly most regulate it so if you're aren't already aware of those rules you might check into them.
 
I am pumping from a creek. I live in one of those free states and free counties and so they dont have much issue with regulations, but thanks for the mention. The amount of water we need is substantial enough that we really need to have a tank. I will have to pump from the running water of the creek around 60 feet away and up around 15 ft and then an additional 8 ft to the top of the tank.. so this needs a fair amount of suction.

I really like the DAB pump. but I see the advantage of a DC motor here. given that, what is a reliable DC pump?
 
Avoid using suction. Put a pump near the creek and push water.

Suction can work (use a foot valve) but tiny leaks let in lots of air.
On the pressure side, tiny leaks let out a small amount of water.
But then you need to be careful about freeze protection.

You don't have much pressure (10 psi plus friction due to velocity) so nothing fancy needed.
There will be a tradeoff, less efficient centrifugal pumps use more power. But cheap and reliable.

Even for centrifugal pumps there are probably different models optimized for different head. Documents I read suggested some may not be happy without sufficient backpressure. An optimum RPM.

In the old days of expensive PV people might use positive displacement pumps, more subject to wear or leaking valves due to grid. But today PV panels are 1/25th the cost of 20 years ago.

I'm not sure which is best pump, however, someone else can chime in on that.
 
vinthewrench said:
I am pumping from a creek. I live in one of those free states and free counties and so they dont have much issue with regulations, but thanks for the mention. The amount of water we need is substantial enough that we really need to have a tank. I will have to pump from the running water of the creek around 60 feet away and up around 15 ft and then an additional 8 ft to the top of the tank.. so this needs a fair amount of suction.

I really like the DAB pump. but I see the advantage of a DC motor here. given that, what is a reliable DC pump?
Click to expand...

About 8 meter high in the air .
Wel you have to see what pomp that can do .
Other way is push and pull systeem.
Means you need 2 pomps to do so .
One pump push it up and the other sucks it up.
Dc power pump are not that strong to do it .
Those pump can push long distance but not up.
 
Don't know how good, but there are PV direct water pumps including pool pumps.
That would be a brushless DC motor (3-phase motor with inverter drive) and MPPT algorithm.

energytheory.com

14 Best Solar Pool Pumps Submersible and Above Ground Models - Energy Theory

The best solar pool pumps include VEVOR Pool Pump, Solariver Pump, Pumpplus, Leblett, Yaminie, and Happybuy Swimming Pool Pump.
energytheory.com energytheory.com

www.solardcpumps.com

PV & DC Direct Pumps | Solar DC Pumps

www.solardcpumps.com www.solardcpumps.com

I think you can also get PV direct controllers for typical 3-phase motors.
 
I'm using an ecoflow delta max (2kwh version) to power a "Green Expert" 1hp jet pump (120v) from Amazon with 400 watts of panels. It's only pulling from 275 gallon IBC totes though...no real vertical lift but it's rated for 150FT High Head and 1200GPH with integrated 20/45psi pressure switch and 5 gallon pressure tank for $275. It's a AIO unit. I don't know what the inrush current is, but the ecoflow handles it and everything was easy as pie to get working. Hook solar up to delta pro, plug in pump and away you go. Also very easy to move around and disassemble for winter.
 
20210524_195116.jpg
I built this a few years ago. It's a 12v system useing a 3.9gpm pump, the cheapest charge controller I could find, a 20w pannel and a 12v timer. It pulls from a shallow well next to it. It's my hands free garden watering system.

You really dont need a huge pump to water crops if your not going a huge area or dont need to move water to a high height.
 

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I just replaced batteries on a guys RPS-800 well. I know very little about that system but i was impressed when i was done and watched it work. My amp clamp showed 7.5 amp discharge from the 48v battery bank, no startup surge either. Its also capable of running directly from solar no batteries installed, he had 800w of panels. In battery mode the unit had a PWM built in to charge batteries.
Not sure how deep the well was, but it was a cased/deep/submersible setup. Guessing between 50ft and 120ft for the area.
 
this is not a little garden, last I checked it was 100 yards x 3 rows of punpkins, lots o water, hence the 2 stage of pump / tank setup.. I will post how this works out.
 
300x16' area needing 1in of water would take 3,000gallons...16hrs at 3gpm. Not that far off my little system...and that's not useing a soakers hose or other water saving measures.
 
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