[RE-wrenches] Oddball pumping question

Thu Mar 27 10:15:17 PDT 2014

Allan,

Chris is on the right track here. Instead of just accepting that they need one huge pump, what you have to do is determine what they are actually trying to accomplish. You will need to know what the total pumping head is and how many gallons per day they need to pump. You will also need to know how they are using the water. If they are just flood-irrigating, where the water just flows out at no pressure, that won't add to the "head", but if they are using large Rainbirds or pivot sprinklers, they will need at least 50 psi at the delivery end to run those sprinklers properly. 50 psi not only adds about 120 feet of head, but it also makes PV-direct pumping harder to do because the pump will run at variable speeds depending on the amount of direct sunlight, which is going to limit the daily pumping time (tracker mounts might help here). If they can install a large tank up on a 120 foot-high hill, then they can get constant 50 psi pressure from the system.

If it's a large diameter well casing (another piece of info needed), you could use multiple smaller solar pumps. I have one customer who was able to get two Grundfos SQFlex pumps down a 5" well, but certainly if you have something like a 36" casing, you could fit a bunch of small pumps in there.

If, however, it's determined that you really do need one huge pump, I suggest that you contact WorldWater and Solar Technologies. They have PV direct pump controllers that can power pumps up to 600HP. Here's their link:

http://www.worldwatersolar.com/capabilities/solar-projects/

I've have not personally dealt with WorldWater, but it looks like they will only do a complete installation themselves, so it cuts you out of the project. Maybe you can get a finder's fee or something.

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 Chris Mason
Sent: Thursday, March 27, 2014 7:20 AM
To: Allan Sindelar; RE-wrenches
Subject: Re: [RE-wrenches] Oddball pumping question

I have a couple of suggestions. A pump motor of that size is likely Class H and requires a 7x starting current or Locked Rotor Amperage. During starting the power factor can drop to .2 or lower and the inrush can run to 20 times the rated run current. Even diesel generators have a very difficult time starting singular loads of this size. I would not even attempt such a task.
That said, the solution is to look at the work to be done. If the intent is to pump, let's say, 10000 gallons in one hour per day, suggest that a solar powered DC pump could accomplish the same in the course of a day. DC pumps are viable speed and don't have inrush currents.

On Thu, Mar 27, 2014 at 10:07 AM, Allan Sindelar <allan at positiveenergysolar.com<mailto:allan at positiveenergysolar.com>> wrote:
Wrenches,
Here's one of the oddest questions I have come across in years:
PRC Commisioner Lyons issued a challenge to NM solar companies today. He stated that he cannot get his electric coop to bring three phase into his property to run his irrigation (a 150 hp motor). He said that whenever he mentions this to a solar outfit - running a 150 hp motor on pv - they look back at him like a deer in the headlights. Can you meet his challenge?
This application is way above my pay grade, and normally I would not give this question much pause, as few ranchers would be seriously willing to put up the money for the design and research time to work up and price a solution, especially given that as far as I know, none even exists. No rural water pumping PV designer that I know works with motor loads of such scale. Indeed, it makes my head spin to think of it.

I checked an older (2003) Franklin motor application guide and found specs for a 150 HP 3 phase motor: 128 kilowatts at 380-575 VAC at 60 Hz.

The only reason I am writing is this: The rancher is one of our state's five Public Regulatory Commissioners. These are the folks who regulate our three private utilities and 20 +/- rural co-ops, and he is perhaps the most conservative one of the five. Last fall he initiated an ill-conceived regulation to cut in half our state's RPS and pushed it through to passage on the PRC; about two months later the ruling was rescinded due to a huge public outcry. So if it were even possible to address his particular request, the potential consequences could have far-reaching effects politically.

Has anyone attempted or accomplished anything even close to this? Is there existing equipment that could handle such an application? Could such an application be justified economically? Or can anyone offer a reasoned answer why it's not possible?

Thank you,
Allan
--
Allan Sindelar
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