We have been having excellent results with the Monoflo line of solar
pumps. Even though this company has been producing progressive-cavity PV
pumps since the 80's in Australia, and their use is so prevelant in many
parts of the world that pumps in general are called "Monos", they have
only begun being marketed here relatively recently. On the down side,
the highest head currently available is 500', so very high heads are
out. Also, they can't accept the multiple types of input that Grundfos
can. On the other hand, they produce more water per Watt than other
solar pumps, have a bulit-in pressure shut off with timed hysteresis
(eliminating external pressure switches, relays, timers, etc), can be
adjusted at the controller to reduce flow in wells that lose recovery
during dry months and, if you happen to have a ranch the size of
Montana, you can monitor pump performance remotely from a computer.
Also, the "CASS" pumps sizing system is extremely accurate and useful.
Please not that we sell many types of pumps and I am not suggesting
buying these pumps but, for wrenches that do a lot of solar pump work,
they do merit looking into.
Matt T
Allan Sindelar wrote:
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
[email protected] <mailto:[email protected]>
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com <http://www.positiveenergysolar.com>
------------------------------------------------------------------------
*From:* [email protected]
[mailto:[email protected]] *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:* [email protected]
[mailto:[email protected]] *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.
www.oasismontana.com <http://www.oasismontana.com/>
www.grid-tie.com <http://www.grid-tie.com/>
www.PVsolarpumps.com <http://www.pvsolarpumps.com/>
------------------------------------------------------------------------
*From:* [email protected]
[mailto:[email protected]] *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
[email protected] <mailto:[email protected]>
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com <http://www.positiveenergysolar.com>
------------------------------------------------------------------------
*From:* [email protected]
[mailto:[email protected]] *On Behalf Of *Lee
Bristol
*Sent:* Thursday, June 11, 2009 1:26 PM
*To:* [email protected]
*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
------------------------------------------------------------------------
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