Solar Panels for farms 2

[lukedesira]

How much of a good idea do you think that solar panels are good to water the crops in a field?

I think its great as when it is sunny, the pv cell will generate enough power to water the crops, and when it is not sunny(possible raining) the fields would require less watering..

am i forgetting something? what are your ideas?

thanks and regards
Luke from malta(eu)

 

[dpc]

How does a PV cell create water exactly?

 

[lukedesira]

The pv cell will provide the electrical power to a pump which will extract water from earth(that is, below ground).

 

[IRstuff]

Negatives:

> Dust
> Other contaminants, like crop dusting
> Damage from farm equipment getting around the panels
> You'll need batteries to store the energy that need maintaining, since the power availability does not always correspond to watering schedules.


TTFN

FAQ731-376

 

[dcasto]

People in the hurry to do PV panels forget the dust thing. IR has most of the cons listed. Keeping up with the electronics, access to service people in rural is more difficult. Put the solar on your house, I'll bet you get a better rate on an industrial/farm meter than your house.

The huge solar farms in CA have special wash systems that clean the flectors with DISTILLED WATER as a film of calcium deposites will knock the effiency down.

 

[lukedesira]

Put the solar on your house, I'll bet you get a better rate on an industrial/farm meter than your house.

that is contradicting .. is better to put it on a house or in a farm?

than agian, its not that much of an option putting it on a house as it is to be used directly for farming, far away from houses..

regards

 

[dcasto]

I was thinking he may have a seperate meter on the water system. A lot of the farmers in CO and KS have this. The farm use gets a different rate and may be tax exempt.

 

[lukedesira]

The whole point of this process is not to pay less money (tax) but to reduce the amount of electricy used, and therefore reducing the amount of CO2 in the atmosphere..

so, basically the pv cell has to be put up on the farm's roof to generate electricity for the water pump.

What I would like to know is what I have to take care of (and possibly how). For example things like dust etc.

thanks!

 

[jfpe]

The real advantage in using a solar electric system for agricultural water pumping is when grid power is not available. The cost of a PV system is often less than the cost of running grid power to a remote grazing site.

Contrary to IRStuff's comment batteries are not typically used in a water pumping system. The water is pumped into a cistern or holding tank during that day, then drawn out as it is needed.

John

 

[lukedesira]

hmm ok.. soo what ur saying is that the pv cells would be used to their full while there would be sun, so when they do not have enough energy they would not need alternate form of energy to extract water out of earth..
good point..thanks


any more suggestions/problems that might be encountered?

 

[dcasto]

lukedesira, this is an engineering site, we base our recommendations on economics and the correct application of the laws of science. We don't take into account a monetary advantage of "it feels good" so it's worth more. If you feel better about cutting CO2 then no amount of engineering will change that.

I've stated that you must clean the surface with distilled water to keep salts from building up. Since the panel must face the south and most places have winds from the south, you might keep this in mind so that you place it on the southside of a dirt road, not the north.

 

[lukedesira]

huh? what about environmental engineering? i mean.. if you can you try to hit 2 birds with 1 stone..

 

[dpc]

Just as a sanity check, you might want to check the power output of solar cells and compare with the power requirements for whatever pumping system you would need. If the area of solar panels needed is too large, you won't have enough space left to farm.

 

[BJC]

How far down is the water and what is the flow rate you can get.
How big is the field? Or
They still make these

http://www.aermotorwindmill.com/Index.asp

The question is how far down in the water ( the head the pump will have meet) and how much water do you need. You can calculate the power you need and size your collectors.
What are you growing? A strorage tank and a drip system makes more sense in a solar powered irrigation system.

 

[dcasto]

Environmental engineering is an extension of all engineering and cost analysis. It would go against my PE to tell a client to spend $1,000,000 on a solar panel system to save $1,000/year in energy. If it was $100,000 per year, I'd give them an option.

Environmental Engineering is not an end unto itself.

 

[dalcazar]

I'm going to pipe in with my two cents since I actually operate a system like this.

I manage an olive processing plant and our irrigation system is off the grid. We water about 6 acres of trees with pumps running off of a battery-PV system. The max output of the system is 3.6 kW and we have 8 deep discharge batteries that actually run everything to do with irrigation. I don't remember the total amp hours stored by the batteries, but it's enough to run the irrigation for about 3 days if the panels were to fault and not charge anymore.

Running a pump directly from a solar panel will indeed allow irrigation to regulate itself as far as how much water is pumped, depending on the insolation that it's recieving. However, depending on the crop and the actual temperature it may be too little or too much water, if you get heavy rain and then a sunny week after that you can add water on top of already saturated soil which could be bad (again, depending on your crop)

what is your irrigation method? what size area are you trying to irrigate? and what is your crop and what kind of pump are you trying to run? PV pumps usually only trickle water unless you have a large PV array and even then finding a DC pump that can handle the power fluctuation is going to be hard. This is the reason we use AC pumps and an inverter to power our irrigation.

 

[BigInch]

One point first. Non-environmental engineering can be an end to itself. I would not want to be an engineers blinded by the idea that money is everything. In addition to maintenance costs of the equipment commonly taught in engineering economics, there may be something else called "maintenance cost of the world", if you like, which has been for the most part totally ignored by engineering curricula. IMO, I think its about time that some less myoptic engineers step up to the plate.

Correct solar panel sizing procedures include a 5 to 10% efficiency reduction for dust accumulation between rains. If you live in an area where rain is scarce and 10% efficiency reductions can be exceeded, they should be manually cleaned at that point. Natural rainfall will be sufficient for cleaning purposes except in the most extreme climates or immediately after plowing activities in the area.

I would want to have some relay that would deactivate the pump circuit at power outputs less than required for efficient pump operation. No point spinning equipment just to increase maintenance cost without getting a sufficient water flow to make it worthwhile.

I think crops can survive without batteries. Not many commercial solar irrigation pump packages come with batteries, so that should be pretty much indicitive of the lack of their necessity.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[PatBethea]

"maintenance cost of the world" . . . pure piffle.

 

[lukedesira]

thanks to everyone who has contributed in this forum..

I really appreciate all the help

regards,
Luke

 

[BigInch]

Pure piffle? No! Simply ANOTHER case of myopia.

Pat, you obviously don't understand my perhaps somewhat exadurated analogy. Should I scale it down for you? Would not pollution from a leaking valve, or single hull tankers, or unlined sedimentation ponds, or gasoline vapors escaping from vapor control systems be a very tangible easily understood example of those hard to define "costs" that most engineers would rather ignore until forced to recon with by the general public that is sick and tired of these kinds of attitudes??????

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain