Water pump for vinyard

[cjb80]

I have a well on some property that I have that is no where near an electric source. I'm planning on using it to irrigate a vinyard via drip lines. I bought a 24v dc submersible pump that draws 4 amps. I am planning on running it off of 2 12v deep cycle marine batteries wired in series, and would like to use a solar panel to keep them charged. What will I need to do this, ie, panel size, charge controller, etc? Any advice would be greatly appreciated.

Cool!

I have a 4 acre vineyard in Oregon that is running all DC pumps and off the grid. The vineyard is about 70 feet higher in elevation than the well is. Our spacing is 7'x5', which is 1250 vines yer acre. I think this equates to around 12 gallons per minute with the half gallon/hr emitters per vine The gallons/minute is important calculation that you need to do; the half gallon/hr emitters actually do something like 0.54 gallons/hr, so it's important to find the actual flow.

I have a barn with a 2600 gallon tank at the elevation of the well. I have a 24V, 5kwh battery that powers the well pump to fill the tank 24/7 as needed. The well pumps around 3 gallons/minute.

Then we have a 3kw array that wired to a submersible pump (panel direct) in the tank that pressurizes a line across the property with a 3HP pump. This is more than enough to overcome the increase in elevation and pressurize the line. It will flow around 25 gallons per minute. Both the well pump and the tank pump are from Sun Pumps; so far they've worked pretty well. The panel direct system works surprisingly well; I have actually ran it while it was cloudy outside and it works for watering 1 acre at a time. The system is designed to water 2 acres at a time to maximize the watering while the sun is shining.

I have another small solar system with two batteries and an inverter that runs the irrigation timer over in the vineyard.

So, the big lesson is that you need to determine how much pressure and flow you need, then you can decide on the pump design, which will drive how big your solar array needs to be. You should consider using a panel direct system as it dramatically reduces the cost of the system. Really, the vines only need to be waters when it's hot/sunny anyways

(There is some evaporation penalty when watering while it is sunny, by the way)

Chris

[Naptown]

Quick back of envelope calculation:

A current of 4 amps for 4 hours will be 16 amp-hours (16AH). To supply that with only 20% discharge, you would need to have a battery capacity of 80AH. Not very big.
And if the pump will be running at the same time that the panels are producing, the load on the batteries will be even less.

Now to keep 80AH batteries at 24 volts happy (charge them at a fast enough rate) you will need at least 160 watts of panels.

Now look at the other side of the equations:

16AH time 24 volts = 384 watt-hours. To put that much power back into the batteries will take more power because of inefficiencies in the batteries and the charge controller (CC)
So figure about 500 watt hours.
If you have the equivalent of 4 hours of full noontime sun at your location, that will take a minimum 125w panel.

You can play it safe and go up in wattage from there.

Now to charge 24 volt batteries you can either get an expensive 24 volt nominal panel and use a cheap Pulse Width Modulation (PWM) CC. Or you can get a cheaper (per watt) panel or two designed for grid tie applications and use an MPPT CC.
(For 24 volt batteries, the two panel voltages will actually be about the same. )

Actually many grid tie panels now a days are 72 cell but generally over 260 watts

[inetdog]

Probably won't run the pump more than a couple of hours per day to water the vineyard, and fill waterers for hogs and chickens. And that will be in the summer months. In the winter probably no more than an hour per day to water animals.

Quick back of envelope calculation:

A current of 4 amps for 4 hours will be 16 amp-hours (16AH). To supply that with only 20% discharge, you would need to have a battery capacity of 80AH. Not very big.
And if the pump will be running at the same time that the panels are producing, the load on the batteries will be even less.

Now to keep 80AH batteries at 24 volts happy (charge them at a fast enough rate) you will need at least 160 watts of panels.

Now look at the other side of the equations:

16AH time 24 volts = 384 watt-hours. To put that much power back into the batteries will take more power because of inefficiencies in the batteries and the charge controller (CC)
So figure about 500 watt hours.
If you have the equivalent of 4 hours of full noontime sun at your location, that will take a minimum 125w panel.

You can play it safe and go up in wattage from there.

Now to charge 24 volt batteries you can either get an expensive 24 volt nominal panel and use a cheap Pulse Width Modulation (PWM) CC. Or you can get a cheaper (per watt) panel or two designed for grid tie applications and use an MPPT CC.
(For 24 volt batteries, the two panel voltages will actually be about the same. )

[dean313]

Critical to your planning is how many hours per day you will be running the pump and whether it will be equal year around or peak in the summer when the panels will be most effective.

Once you have the hours you have the energy load per day and calculating the battery size for no more than 20% discharge and the panels to recharge them becomes simple, using one or more of the calculators linked to sticky threads.

One good factor is that you probably will not need to pump, at least not as heavily, on days when clouds block the sun.

Probably won't run the pump more than a couple of hours per day to water the vineyard, and fill waterers for hogs and chickens. And that will be in the summer months. In the winter probably no more than an hour per day to water animals.

[inetdog]

I have a well on some property that I have that is no where near an electric source. I'm planning on using it to irrigate a vinyard via drip lines. I bought a 24v dc submersible pump that draws 4 amps. I am planning on running it off of 2 12v deep cycle marine batteries wired in series, and would like to use a solar panel to keep them charged. What will I need to do this, ie, panel size, charge controller, etc? Any advice would be greatly appreciated.

Critical to your planning is how many hours per day you will be running the pump and whether it will be equal year around or peak in the summer when the panels will be most effective.

Once you have the hours you have the energy load per day and calculating the battery size for no more than 20% discharge and the panels to recharge them becomes simple, using one or more of the calculators linked to sticky threads.

One good factor is that you probably will not need to pump, at least not as heavily, on days when clouds block the sun.

[dean313]

I have a well on some property that I have that is no where near an electric source. I'm planning on using it to irrigate a vinyard via drip lines. I bought a 24v dc submersible pump that draws 4 amps. I am planning on running it off of 2 12v deep cycle marine batteries wired in series, and would like to use a solar panel to keep them charged. What will I need to do this, ie, panel size, charge controller, etc? Any advice would be greatly appreciated.