[RE-wrenches] Design help for solar water pumping application
Matt Tritt
solarone at charter.net
Sun Jun 14 21:24:45 PDT 2009
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
>
> Allan at positiveenergysolar.com <mailto: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 <http://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.
>
> www.oasismontana.com <http://www.oasismontana.com/>
>
>
>
> www.grid-tie.com <http://www.grid-tie.com/>
>
>
>
> www.PVsolarpumps.com <http://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
>
> Allan at positiveenergysolar.com <mailto: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 <http://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
>
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