# 40hp submersible pump design problem

1 Posts
Nov 27, 2008 08:54 am
40hp submersible pump design problem

hi everybody I am newbie about solar
my pump specifications are voltage=220/380(L-G/L-L voltage i mean three phase ), amper=60A.
1.Q)how much  I need power or pv modul for this can you give  me examples in details or illustrate design i want to use 200watt pv moduls
2.Q)which type inverter  I chose (I think  sma sunnny because they say that you can use three inverter in parallel,  is it secure ) and
most inverters output power is for american standards but i am in europes is it adjustable  for 220v
3.Q)pump need to be work at three hours without pv at night
how  much do I need battery bank and connecting batteries in series or parallel which one I prefer

220 Posts
Nov 27, 2008 11:15 am
Re: 40hp submersible pump design problem

hello aslan,

yikes! i'm not sure you will want the details when i say that we are talking about a \$150,000 usd pv system here? (low ballpark)

best regards

163 Posts
Nov 27, 2008 12:20 pm
Re: 40hp submersible pump design problem

That looks like a very low ballpark figure. 40hp is 30Kilowatts. If he wants to run it for 3 hours at night that is approximately 100kwh. That would require about 500 batteries of the 12V 100AH type to keep his total battery discharge at night below 20%. Batteries alone could cost more than \$100K.

Using a nominal figure of 4 hours of peak sun per day, he will require at least 25kilowatts of pv panels just to recharge the batteries to run the motor at night, and another 30kilowatts of pv panels minimum to run the pump for 4 hours during the day. If he wants to run the pump for more than 4 hours during dayling then more pv panels will have to be added accordingly. This looks like a problem where PV is not necessarily the best solution.

Nov 29, 2008 07:07 pm
Re: 40hp submersible pump design problem

Aslan, it would be wiser to construct a water tower and use a smaller pump that would run all during the daytime straight from a smaller PV array.
In a 24 hour period, one day and night, worst case, how many liters of water are required?
Would it be pumping water from a deep well?
How deep?
What is the terrain like at this location, foothills, flat lands, bottom land?
Is there a full, clear view of sunrise and sunset and allthroughout the day, summer and winter?
No trees or buildings or mountains that block the Sun for even part of the day?
Whats the weather like year around?
All of these things make a huge difference in the size and therefore cost, of the PV array.

If the terrain would allow it, there is the possibilty of just setting a tank on high ground and so the need to construct a water tower would not be nescessary. Something to keep in mind is, (every foot of elevation is about 1.5 lbs.psi. 80 foot of elevation will provide about 50 psi.This is wrong.) Correction! 1 foot of eleavation is equal to 0.433 lbs. psi.
Not sure what that would be exactly in metric.

« Last Edit: Nov 30, 2008 07:10 am by Thomas Allen Schmidt »

351 Posts
Nov 30, 2008 02:15 am
Re: 40hp submersible pump design problem

Thomas:

Each foot of water is about 0.433 psi. You would need about
115 feet to obtain 50 psig.
Metric equivalent
3.5 kilograms per square centimeter at 35 meters.

Ken

Nov 30, 2008 07:04 am
Re: 40hp submersible pump design problem

I stand corrected. Thank you Ken. I was basing this on my system which is 30 foot high and the water pressure gauge I use reads 18 lbs. psi. but I divided 30 by 18 instead of 18 by 30 which is still high but that could be in the gauge or the difference in elevation from actual water top height and pressure gauge. My apologies Aslan.

351 Posts
Nov 30, 2008 12:09 pm
Re: 40hp submersible pump design problem

Your gauge is reading the difference in elevation between it and the actual water level in the tank.  Even though it may not be perfectly calibrated in psi, the relative readings should be quite accurate.  If it has a large enough scale, you can "gauge" your water storage level fairly closely, with a little practice.
Ken

Nov 30, 2008 02:28 pm
Re: 40hp submersible pump design problem

Going with 1' = 0.433 lbs. psi.
18 lbs. psi. would be 41.5'
I know thats not right. Must be the gauge. I think I paid \$2 for it. At most with a full 1,000 gal. tank, top of water is 36' to Earth. Then there is a 4' difference in ground elevation to where the gauge is located but its 3.5' from the ground. So at most I have 15.8 lbs. psi. I didn't include what is beneath ground because thats 2' at both ends and cancels itself out anyway.
One thing I did to compensate for low pressure was to increase volume by keeping pipe size large all the way up to the cutoff valve for each water outlet. It starts out as 3" down pipe then goes to 2" underground where it comes up to a manifold and reduces to 1.25" and then .75" all the way to the sinks and shower and so on. Of course I had to remove any flow reducers like the water saver device in the conversion valve. Everything works as if it were at a higher pressure unless several outlets are open at once then it slows down considerably but this hasn't been a problem for us. If it every does, its a simple mater to install a booster pump, tank, and pressure switch.
I was expecting to have a water hammer problem but to my surprise it didn't.

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