[RE-wrenches] Design help for solar water pumping application

Sun Jun 14 15:07:23 PDT 2009

What if you filled the top tank and over flowed to the lower tank and did
your shut off there? Or parallel the fill call with a normally closed
solenoid to stop fill on whichever tank. I have done this several times with
not a problem. 

Just like having the inverter start the generator and also having a pressure
switch and a spring wound timer start the gen. too.

If this is out of whack ,  Pleas Ignore I did not read the earlier threads.

Dana Orzel

Great Solar Works, Inc

www.solarwork.com

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

“I'd put my money on solar energy
 I hope we don't have to wait 'til oil and
coal run out before we tackle that.”

—Thomas Edison, in conversation with Henry Ford and Harvey Firestone, March
1931

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Sunday, June 14, 2009 12:34 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Design help for solar water pumping application

I agree with Brian and Mark on most of their comments, but here’s a bit
more:

Mark is right, there’s no way to separately control filling two tanks at
different levels. I didn’t read that section very carefully. Brian’s float
valve approach and sequential filling is about the only approach. But given
that a float valve failure could be catastrophic (5,000 gallons flowing back
down) you might want to add a check valve on the line to the higher tank, if
the line from the well to the two tanks is shared.

Remember, too, that the total dynamic head is measured from the water level
in the well, not the pump level. That means your tdh on the far well is
something less than 220’, or about 97 psi (plus friction head). Assuming you
don’t have 3,000 feet of signal cable in the ground, the P2Flow approach
would likely work well. Their 0-100psi transducer has a resolution of 0.1
psi. Make sure to add a check valve where the line leaves the well, so as to
be unaffected by fluctuations of the water level in the well, and put the
pressure-sensing transducer after the check valve, so that it only measures
head determined by the tank level. We’re working with a similar application
here in New Mexico, so I’m learning this too.

One respectful disagreement with Mark: The 3SQF-3 Grundfos is officially
rated to 656’. I hear it will do well more than that, but no direct
experience. I would not recommend the Lorentz after multiple failures back
when Dankoff (now Conergy) was the sole North American distributor. (We are
in Santa Fe so do will call pickups for most orders. Don’t ask me to
describe seeing pallets of junk Lorentz pumps outside their warehouse,
waiting to head to the recycler.)

Allan Sindelar

Allan at positiveenergysolar.com

NABCEP Certified Photovoltaic Installer

EE98J Journeyman Electrician

Positive Energy, Inc.

3201 Calle Marie

Santa Fe, New Mexico 87507

505 424-1112

www.positiveenergysolar.com

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Brian
Teitelbaum
Sent: Friday, June 12, 2009 2:18 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Design help for solar water pumping application

Hi Lee,

I don’t know how the two tanks are laid out physically, but if they happen
to be installed in a way that you could run one pipeline up to the tank at
200’ and go from there to the other tank, you might try using a float valve
in the lower tank and a float switch in the upper tank. The lower tank’s
inlet would just be “teed” off of the pipeline going to the upper tank. The
lower tank will fill first, being the path of least resistance. When it is
full, the float valve closes sending water through the pipeline to the upper
tank. When the upper tank is full, the float switch would turn the pump off.

The distance to the float switch in the upper tank is a bit far, but you
should be OK if you use a larger gauge wire than usual. I think that 18
gauge would be fine, but 16 gauge would be better. If it is line-of-site,
you might look into doing a wireless control , but that would mean that you
need a small PV module and a battery up there.

Go with the 1 ½” pipe

Not to contradict Mark (Ok
I guess that I am!) The Grundfos model 3 SQF-3
will do 600’

As to Allen’s comment about array size, he is correct about the pump drawing
a max of 900W. However, if you only put a 900W array on the pump, it will
only pump at max volume at mid-day. If you put a larger array on the pump,
the array will produce 900W in less light (morning and afternoon) and
produce a lot more gallons per day (GPD). The GPM figure of a solar pump is
really only relevant for making sure that you don’t over pump a low yielding
well. It’s really GPD that counts. That 1.36kW array might produce 900W at
9AM and 3PM, giving you a solid six hours of max output pumping. No problem
over sizing the array – the pump will only draw what it needs. If you have
really good exposure to the sky, you can use a tracker to increase GPD
instead of over sizing the PV.

According to my info, with 250” of head (220’ plus pipe friction loss) you
can get about 2000 GPD (summer) with the Grundfos model 6 SQF-2 and about
700W of PV in a fixed array, with a peak flow of 4.5 GPM. Adding more PV
will give you more GPD. With the model 11 SQF-2, you can get up to about
4300 GPD with a 1750W array at that head. If you needed even more water
volume, and the well produced it, you could even put two pumps in the well
(with separate arrays). I had one dealer who managed to put two Grundfos
pumps down a 5” casing! He said that it all went easy
.but I don’t believe
him. He did have a curious issue though. He said that if he turned one pump
off with its CU200, both pumps would shut down, even though the other pump
was not connected to that CU200. He couldn’t just run one pump. I never did
talk to Grundfos about that.

Cheers!

Brian Teitelbaum

AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Dickson
Sent: Thursday, June 11, 2009 9:40 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Design help for solar water pumping application

Hey Lee, 

Allan is right in that the WINcaps software is a lifesaver and FREE!  Not to
contradict Allan, but I do not see a feasible way of using two float
switches in separate tanks with only one pump controller.  Also, the 3000’
distance is a little far—they usually recommend a max distance of 1600’ for
the float switches.  Lastly, if you are ever worried about the head, the
Lorentz pumps can pump up to 760’ --more than double the recommended for
Grundfos.  

I highly recommend Genpro Energy Solutions as a pump distributor for both of
those brands.  They always answer the phone, are personable and return
emails (hint, hint Conergy)!

Best, 

Mark Dickson

Oasis Montana Inc.

 <http://www.oasismontana.com/> www.oasismontana.com

www.grid-tie.com <http://www.grid-tie.com/> 

 <http://www.pvsolarpumps.com/> www.PVsolarpumps.com 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Thursday, June 11, 2009 2:28 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Design help for solar water pumping application

Lee,

You can get Grundfos’ WINCaps software from your RE or pump supplier; some
will run the sizing for you (Jeremy at Conergy does for us). I didn’t check
your head and flow, but I would expect that’s about your only good pump
choice at that head. Add a tracker if you need greater summer output; don’t
attempt batteries as a solution. If usage occasionally exceeds output, add
an IO101 control and allow the pump to run off any AC source at night. A
tiny 1,200W inverter/generator will work at sea level. Use a CU200
controller to allow a float or level detector switch to turn off the pump
when tanks are full. Mercury-based float switches last longer in signal
circuits that carry no current. If you can’t use a float switch because the
lines are already buried, look into www.P2Flow.com <http://www.p2flow.com/>
for pressure transducer-based control. Read the website info, then call
Britt there with your specific application. That array sounds oversized, as
the pump draws a maximum of 900 watts. Hope this helps.

Allan Sindelar

 <mailto:Allan at positiveenergysolar.com> Allan at positiveenergysolar.com

NABCEP Certified Photovoltaic Installer

EE98J Journeyman Electrician

Positive Energy, Inc.

3201 Calle Marie

Santa Fe, New Mexico 87507

505 424-1112

 <http://www.positiveenergysolar.com> www.positiveenergysolar.com

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Lee Bristol
Sent: Thursday, June 11, 2009 1:26 PM
To: RE-wrenches at lists.re-wrenches.org
Subject: [RE-wrenches] Design help for solar water pumping application

Solar Water Pumping Wrenches,

We normally don't do solar water pumping but a friend asked for some help
designing his system.  He has one well and two 5,000 gallon reservoirs to
fill up.  The average usage is expected to be about 2,000 gallons per day
but may be higher in the summer.  The tanks will have level detector
switches to sense when the tank is full.  The site is near Leesburg, VA.

The problem is to design a control system to turn on the pump when one or
both of the tanks needs water and to shut it off when both are full.  The
closest tank has a head requirement of 200 feet (pump to tank) and is 300
feet from the well head.  The second tank head requirement is 220 feet and
it is 3,000 feet from the well.  The pipes are expected to be 1.25 or 1.5
inch.

A Grundfos SQFlex 6 SQF-2 pump with 1.36 KW solar was recommended, 360 foot
head, 360 gph.  I think that this would provide the lift but not the
quantity.  Hmmmm, what valves and controls would you all suggest?

Thanks!
Lee

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20090614/28c7fb76/attachment-0004.html>