Solar water pump selection

[Eng_Ragy]

hello;

pump.jpg

I currently using diesel generator to run the attached pump specification 7.2 and 9.2 KW and i would ask is it possible to run it with off-gird system ?


1- There no way to get gird to this place that's why i said off-gird system
2- I know it will be costly because using 3-phase inverter . will it reach more than 100K USD for one pump?
3- can i replace this pump with DC pump with same specification but as i know and correct me please if i am wrong the maximum DC pump is 1 or 2 HP
4- If i need to run this system only during sun peak, do i need a lot of battery bank ?
5-The performance of the pump will be the same if i used off-gird system compared with generator.


P.S: I hope you guys can understand my questions and sorry for poor English

Thanks;

[Mike90250]

I don't know of any reports of any off grid, 3 phase systems being successfully implemented.

Which pump are your using 7KW or 9KW or Both at the same time ? That's a lot of power.

I assume you are using this for irrigation. Any chance the pump salesman sold you a much larger pump than you really need? Solar is about conserving energy, so there are not a lot of high power choices.

The inverters will be expensive, about $7,000 each, and you would need 3 of them, some sort of control box and a huge battery bank.

The PV panels will need to also be an extensive array, somewhere between 15-20 KW of installed panels (for a 10KW motor), many charge controllers, and lots of structure to hold it all together, this is a very large project.

[Eng_Ragy]

I don't know of any reports of any off grid, 3 phase systems being successfully implemented.

Which pump are your using 7KW or 9KW or Both at the same time ? That's a lot of power.

I assume you are using this for irrigation. Any chance the pump salesman sold you a much larger pump than you really need? Solar is about conserving energy, so there are not a lot of high power choices.

The inverters will be expensive, about $7,000 each, and you would need 3 of them, some sort of control box and a huge battery bank.

The PV panels will need to also be an extensive array, somewhere between 15-20 KW of installed panels (for a 10KW motor), many charge controllers, and lots of structure to hold it all together, this is a very large project.

Thanks for reply and yes you are right this for irrigation and i use 7KW for farm (35 acres) and the 9 KW for another farm ( 50 acres) and each one have generator but i was asking is solar system off-grid more efficient than diesel generator

and the price of each system will go a round 50K to 60K usd ?


and what about DC pump is it can handle same amount of m3/h as AC pump,

If i need to run this system only during sun peak, do i need a lot of battery bank ?

Thanks;

[Mike90250]

You are going to need to hire a local expert to design this. We can say "yes, that sounds about right" or "No, that salesman is a fool, trying to steal your money for something that has no chance of working." But we can't do a $5,000 engineering job for you over a forum.

[Eng_Ragy]

You are going to need to hire a local expert to design this. We can say "yes, that sounds about right" or "No, that salesman is a fool, trying to steal your money for something that has no chance of working." But we can't do a $5,000 engineering job for you over a forum.

correct me if i am wrong:

DC (brush less ) pump (submersible) maximum range around 10 HP

which better for solar DC pump 10HP or AC pump 10HP and what the difference pleasse ?

Thanks mike;

[Eng_Ragy]

hello ....

[Mike90250]

correct me if i am wrong:

DC (brush less ) pump (submersible) maximum range around 10 HP

which better for solar DC pump 10HP or AC pump 10HP and what the difference pleasse ?

Thanks mike;

We are not pump salesmen, and I don't know what the max DC HP is. 40 years ago, I used a variable speed, 50hp DC motor to drive a 400Hz aircraft generator. So I know that if you have the $$, they can make a motor for it.

For Solar, a DC pump saves the trouble of buying a 3 phase inverter and battery bank. The DC motor likely has it's own special power conditioner to run it.

[cjb80]

correct me if i am wrong:

DC (brush less ) pump (submersible) maximum range around 10 HP

which better for solar DC pump 10HP or AC pump 10HP and what the difference pleasse ?

Thanks mike;

I don't think the efficiency of DC vs AC is the (important) issue, really. There are brushless DC pumps out there that are probably very close to AC pumps in terms of efficiency. If you ran solar with an inverter then I would have much more confidence in saying that a DC pump would be more efficient than DC->AC then running an AC pump.

The question you should be asking yourself is if a 10 HP DC pump is made by anyone. The company that I would call to discuss this is SunPumps. From what I have gathered, they take pump parts and put them together in various combinations and then run them using DC electronics. Their pumps are "3-phase DC", which means that it takes 4 wires and then it has an electronic controller that manages the power across three conductors in a manner that is similar to an AC pump. My understanding is shaky, but I think that the electronics choose a desired rotation speed (based on input voltage and various other settings) of the pump impeller and then trigger impulses across the three conductors in a synchronized manner with the rotation of the impeller.

Anyways, I have a 3 HP, "3-phase DC" pump and it works really well. It sounds like a jet engine. I know that SunPumps makes a 4 HP one but I am not sure if they go up to 10 HP... By the way, I have a ~3kw array to power 3 HP, so the array would need to be quite large to power 10 HP... (like 35-40 285 watt panels to make a 10kw array)

Chris

[russ]

Anyways, I have a 3 HP, "3-phase DC" pump and it works really well.

3 phase DC?

[cjb80]

3 phase DC?

I am aware that the term "3-phase DC" makes no sense, hence the quotes. In any case, that is the term that the company uses.

[russ]

I am aware that the term "3-phase DC" makes no sense, hence the quotes. In any case, that is the term that the company uses.

Someone that knows will be along soon I expect.

[cjb80]

Someone that knows will be along soon I expect.

Knows what? I am unaware of any open questions in my statements, except perhaps the details of what "three phase DC" means or how it is implemented.

Here is a manual for one of the controllers from Sun Pumps that uses this term: http://www.sunpumps.com/uploads/series/DocFile1_242.pdf
Look on page three or search for "three phase". I asked Sun Pumps what this means and if it has an inverter inside; they stated that there is no inverter and the description that they gave me on how it works is similar to what I stated in my previous posting. Anyways, their technical staff is pretty good so if you're curious I imagine you could give them a call and they'd tell you what's going on inside their electronics.

Chris

[Mike90250]

Brushless DC motors use electronic commutation, and its sort of like poly phase AC, which smoothly drags the rotor around. The RPM's can be sensed by feedback in the power lines, and the controller knows how fast to switch the signals from wire to wire.

[cjb80]

Brushless DC motors use electronic commutation, and its sort of like poly phase AC, which smoothly drags the rotor around. The RPM's can be sensed by feedback in the power lines, and the controller knows how fast to switch the signals from wire to wire.

Cool, here is a link that I found that describes how it works.

http://fab.cba.mit.edu/classes/MIT/961.04/topics/brushless_DC1.pdf

[russ]

A chopped DC current then?