50hp pump from well

bghayad · November 2014

Hello;

We have pump that takes 50 hp and is able to withdraw 10inch water from 200m well depth and there is not electricity in this area so we are thinking if possible to use the electrical solar solution but of course it will be costly because of the required energy for this pump.

But, actually the water existed at 50m depth although this pump able withdraw water from 200m depth but in this site it is only withdrawing from 50m depth because the water existed at this depth. Again, the water pipe thickness is 10 inch.

My questions are:
1) Do I have to design the solar system power based on the 50hp (the complete power of the pump) that is able to withdraw from 200m depth or it is enough to design at 13hp (50/4 = 13.3hp) as the water existed at 50m depth so I am assuming that the required energy to withdraw water from 50m is one quarter amount of the required energy to withdraw water from 200m. Or this pump needs 50hp even if the water will be withdraw from 1m?

2) For such case, what is the suggested idea to get solution in the best amount as the 50hp is really too much value.

And I am fully thanks for all the helper.

Regards
Bilal

BB. · November 2014

Re: 50hp pump from well

The pump only uses the amount of energy to lift the water from the level of the water in the well to the surface plus the pressure needed above ground (near zero if pumping to open water tank, or plus the energy to raise the pressure to XX PSI or kPA).

When pumping, the water level in the well will drop--How much depends on the "recharge" capacity of the well (how deep it is drilled, how easy water moves through the soil is, how fast you are pumping water out, etc.). That your well driller can help you with (and test pumping the well, etc.).

Also, there are many types of well pumps. There are centrifugal pumps (sort of like a "fan" or vacuum cleaner) that use more power as the rate of water flow goes up (you can reduce power needs on this type of pump by using a valve to reduce water flow).

And there are positive displacement pumps. These types of pumps, if you place a restriction valve on the output, will use more energy because they have to move X amount of water for every revolution of the shaft.

https://en.wikipedia.org/wiki/Pump

Both types of pumps are used in wells. And for wells more than a few meters deep, you have to place the pump itself in the well below the water level to lift the water (a pump will draw a vacuum and lift the water only ~20 feet maximum).

So--The type of pump will greatly affect the loading on the motor. There is a lot of understand and research here.

Next, the motor. With solar power, you are usually trying for as high efficiency system as you can. An efficient pump is one part of the solution, and an efficient motor is the other part.

The common type of motor of this size is usually a 3 phase induction motor. There are other types, a 3 phase permanent magnet (or synchronous) motor would be something like 20-25% more efficient than induction motors.

https://en.wikipedia.org/wiki/Induction_motor
https://en.wikipedia.org/wiki/Synchronous_motor

They each have their positive and negatives--But the "new thing" is to drive these motors with a variable frequency drive.

https://en.wikipedia.org/wiki/Variable-frequency_drive

A VFD (variable frequency drive) is, more or less, a 3 phase AC inverter--Pretty similar to what we use for off grid power today. The difference is, besides generating three phase power, is that they don't hold 50/60 Hz output, but can vary from near zero Hz to over 50/60 Hz. This gives you the ability to adjust the speed of the motor to the pumping requirements, and it also allows you to slow the pump down when there is less solar power available.

A typical VFD takes AC utility power in, changes it to DC power (rectifier+capacitors), and then changes it back to 3 phase power out. For solar, the solar panels are connected to the DC section of the VFD and then generate the AC output.

None of this is "simple". And a 50 HP pump is very large and expensive, plus the solar power + VFD to drive a 50 HP pump is not cheap either.

Anyway, here are a few discussions with a person or two who has successfully found the parts and installed a solar-VFD-pump installation overseas (at least overseas from me

).

BB. wrote: »

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)

You need to look at this as a "system". In some cases it may be best to have a single pump (well to pump to point of use). Other times, it may be better to pump to a tank/pond from the well, and a second set of pumps to bring water to the home/field/etc.

Do some reading and then ask some more questions, and we will do what we can to help.

I am not a well person or an off grid systems engineer--So I will do the best I can to help where I can.

-Bill

waynefromnscanada · November 2014

Re: 50hp pump from well

BB. wrote: »

Also, there are many types of well pumps. There are centrifugal pumps that use more power as the rate of water flow goes up (you can reduce power needs on this type of pump by using a valve to reduce water flow). -Bill

WOW! It's refreshing to see there's someone on this forum who understands that characteristic of centrifugal pumps! Unfortunately it often seems many "real well and pump people" don't understand that issue. And almost all off the shelf submersible deep well pumps are in fact centrifugal designs.

mike95490 · November 2014

Re: 50hp pump from well

if 1hp is 750w, then you are looking at around 40Kw of PV array to fully power that pump. That's going to be pretty large, and awfully expensive.
Is it OK to just run on sunny days, or do you need nighttime / battery power.

Texas Wellman · November 2014

Re: 50hp pump from well

The higher the water level the more water your 50 HP pump will move and the more energy it will consume.

What are your water needs?

Gaarkuteer · September 2017

Thank you for this forum, speaking from Jos Plateau State Nigeria. I really needs help on how to design a circuit of solar without battery that can pump water from a 78m depth borehole and what type of pump will best serve me for irrigation that can pump water atleast 10hrs per day

Dave Angelini · September 2017

Look at Grundfos! 10 hours a day sounds like you need a type SQF pump. Do you have a dealer there who you will buy from as they can help with the model of the pump? Good Luck! You probably do not need the 50HP as the thread title here BTW.

jonr · September 2017

I would start another topic. But a short answer is a Grundfos SQFlex model 6 SQF-3.

50hp pump from well

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