Help With Solar Irrigation Set-Up For 2 Acre Farm

Heather Lentz

How many batteries, what size inverter and panels do I need to run my pump for drip irrigation.

My pump is a Simer 1-1/2 hp Sprinkler Pump (19.2amps@115v) that would run for 4 hours per day.

Photowhit

We would need to know the location to give you a more complete idea, and there are likely more efficient ways to run a drip irrigation....

... but you're looking at about a 2500 watt load for 4 hours. If you intend to run on battery only and are in a location with very cloudy days, you would need 10 Kwh (kilowatt hours) of available storage, with the 'normal' use of top 50% only a 20kwh battery bank, but since you want to run such a high drain load 2500watts or 1/8th of a 20Kwh battery bank, you will also loose energy to Peukert's law. Batteries for solar are generally rated at a discharge of 1/20th of capacity. The batteries effective capacity diminishes with higher draws. For example my 24 volt is a 804 amp hour battery rated at the 20 hour rate, but only a 510 amp hour battery at 6 hour rate.

So just a general shot at your system would be a 28-40Kwh battery bank, you would want an array to charge the bank at a minimum of 10% charging rate, or @ 63 amps at 48 volts or delivering about (48x63) 3000 watts solar panel put out roughly 75% of their panel rating on normal days so around 4000 watt array. Just ball park numbers...

MarkC

I'm sure you are aware that a DC pump with appropriate storage might be a more efficient way to handle this requirement. It might pay to actually elevate the storage - with a properly designed drip (low discharge pressure) system.

Heather Lentz

Our farm is in Northern Michigan.

The flow rate for 2 acres is 1344 gph. (We intend to have 10 acres in the future.)

It is broken up into 3 zones. Each would be run for two hours every other day in the summer.

The pump is rated at 45gpm.

BB.

Off Grid Solar Power is pretty expensive (panels + charge controller + battery bank + AC inverter)...

More or less, grid power costs around $0.10 to $0.20 per kWH -- depending on your utility costs.

Off grid solar power (battery based) can be as much as $1-$2+ per kWH (it can be less--depending on your purchase and maintenance costs).

There are other ways of moving water... One is to get a solar pump (or pump + VFD--Variable Frequency Drive) which can connect directly to solar panels (no battery bank). The pump only works when the sun is shining and will have variable output (GPH/Pressure) depending on the time off day/amount of sun.

Typically these type of pumps will be used to fill a cistern/pond/elevated tank. Then you use gravity (or a separate smaller pressure pump) to move water to where you need it.

Solar power is expensive, so conservation is a big help (water pressure/volume to a minimum) and choosing the right pump (day time/sunlight pumping only, or in poor weather--I.e., need battery bank), etc...

Do you have any access to utility power?

-Bill

Heather Lentz

We do not have power. The well is 600+ feet back on property. We already have pump and irrigation lines. I am looking to price out solar so I can have a comparison.

The volume of water needed to water our crop would require to large of a tank to work for our situation.

mike95490

Solar/battery pumping is going to be pricey. I drip irrigate a hazel orchard and have 3,000 gal of storage, 160' up on a hill. I pump into that on sunny days, and have to run generator or skip watering. Running the pump off my batteries will flatten them in a couple hours. I've run 2,000 feet of 2.5" pipe (in trenches) to transport the water, and use a conventional deep well pump to get the water up the hill to the gravity tanks.

Heather Lentz

Our land is flat. I really don't see the stored water working for us.

Can I run solar with an inverter and not use the batteries?

I understand that it would only run when the sun was out.

BB.

There are smaller pumps that are direct connect to solar panels--But they are not cheap:

http://www.solar-electric.com/wind-and-water-products/sodcwapu/grsoposuwapu.html
http://www.solar-electric.com/wind-and-water-products/sodcwapu/sun-pumps.html
http://www.solarpumps.com/flow-chart-ranch-pump.html

And there are larger pumps/setups:

Some discussions about VFD (Variable Frequency Drives)... Basically a variable frequency inverter with (typically) three phase output. Used to soft start motors (handy for 3 phase well pumps, or pumps with well head starting capacitor) and can also turn an AC motor into a variable speed motor (very handy for pumping applications).

WELL PUMP and Inverter QUESTION
Wind/solar for large scale pumping etc (out of my depth!)
could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC (new link/thread 10/27/2012)
Help required to design off grid system (information on possibilities to connect "standard VFDs direct to solar panels) (new link 1/13/2013)

This last set of links shows some relatively large pumping applications... I am not sure they would work well (i.e., cost effectively) with higher pressure drip irrigation--But if you pump in the middle of the day during sunny weather--May be possible.

-Bill

mike95490

What's the lowest pressure your drip system will work ? Build a hill (call it a burial mound ! ) and put your storage tanks on it. When there is some clouds, your power will crash and your pump shut down, elevated storage is way less expensive than a huge battery bank. You are talking a huge scale here,