Here's what worked and what did not...
Let me begin by repeating that the well is low-yield, testing at 0.5 Gallons Per Minute (GPM) output in October of 2010. Keep this number in mind for later. The well is 305' and the static water level is 170'-180'. I measured this static water level many times throughout 2011 and that seemed to be stable. The water storage column of this well's 4" casing is about 81 gallons.
I have no AC power to the site. Solar seemed the best option.
Selecting a solar pump was difficult in that most of the available pumps, like the expensive high quality German GrundFOS SQ and the Lorentz pumps, and the newer less expensive Chinese pumps (Bison, Sun Pumps), all pump at 5 GPM or higher. They also require a long run of large gauge copper (2GA?) cable down into a deep well, and ~300' of 2GA copper cable is REALLY expensive right now.
Over-pumping is bad for a well, and dry-pumping will destroy the pump quickly. For AC powered pumps, you can use devices like a Coyote Pump Protector to cycle the pump to match recharge and not stress the well or pump. No straightforward cycling solution seemed available for DC pumps, at least that I could find. In retrospect, that was certainly not the case.
The pump that I found that offered an output to match the well recharge was the Simple Pump:http://www.simplepump.com/
At it's heart, the Simple Pump is a quality and high efficiency hand pump that can be retrofitted with a DC motor. It will pump about 0.5 GPM from a maximum depth of 200', with higher ouput rates for wells shallower than that. I believe they have a 48V solution for even deeper wells. The warrenty is outstanding. It gets fine reviews by users.
The Simple Pump is different from the other brands I mentioned in that it sucks water to the surface by a rod and lever arrangement rather than pushing up from a submersible pump. Windmill water pumps operate like this.
Build quality is very high, mostly stainless steel, and support by Gary Wittig, the business owner, is a phone call, or email away.
The system requires installation of 9' sections of Schedule 80 threaded PVC drop pipe, and custom fiberglass sucker rods to the depth where you will draw water from. In my case, this was to be 290', providing an ample water reservoir to draw on given the low recharge of the well. Actual lift is from the static water level: 180' in my case. A very nice feature is that the system is freeze proof due to an ingenious drain arrangement six feet below the pump head. When not un use, water drains back to that level.
My following comments apply to deep well installations of the Simple Pump ONLY. I would HIGHLY recommend this pump (handpump or motorized version) for wells shallower than about 150'. Installation and maintenance would be a snap by two strong people.
However, using the Simple Pump for a deep, low-flow well, is more challenging. [Edit - Feb 2013: Simple Pump has developed a mechanical pump lifter. If it works as advertised this would make installation removal/maintenance much easier for the 150' to 300' deep well: http://www.simplepump.com/Support-PDFs/SIMPLEPUMP-Pump-Installation-Lift-Install.pdf ][Edit - Gary will not sell these to the public. After talking with him, it sounds like there is a risk of having the pipe column slip down into the well, and he does not want to assume this risk. This is an assumption on my part, but he did not want to sell me one. ]
Installation and maintenance are a bear due mainly to the great weight of the system.
The procedure for threading the pipe and rod is not difficult, and we elected to do it ourselves. My friend Glenn and I muscled that pipe and rod down the well, sterilizing with bleach as we went. Glenn even developed a trick with a Prussic knot and some paracord to control the rate of decent of the drop pipe. There is a "safety tool" and T attachment that prevents dropping the whole column down the well, but in my opinion, the tool is close to failure (splaying outwards) under the weight of 290' of pipe and rod AND water. I've noted this to Simple Pump, and hope for a remedy. Perhaps the tool can be beefed up a bit with some metal stronger than aluminum. Simple Pump did not seem responsive to my concern. I don't know if they have addressed this since or not.
The installation process felt increasingly dangerous as we dropped more pipe and rod into the well.
I would STRONGLY urge anyone installing a Simple Pump into a deep well of more than 150', to hire an open minded well rigger who is willing to learn a unique new installation procedure, has a crane truck, and two strong assistants at hand.[Edit - Feb 2013: Simple Pump has developed a mechanical pump lifter. If it works as advertised this would make installation removal/maintenance much easier for the 150' to 300' deep well: http://www.simplepump.com/Support-PDFs/SIMPLEPUMP-Pump-Installation-Lift-Install.pdf ]
Anyway, we got the drop-pipe in place, and hooked up the hand pump, and found some binding of the sucker rod. The two of us manned two 9' sections up by hand. The pipe column now had water in it and was MUCH heavier, it was a truly frightening experience. We found the source of the binding; a little plastic guide called a Spider was not in place quite straight. Very fortunately this problem was near the top of the pipe column. We also found that while the sucker rod screws together easily, unscrewing it is very difficult, and you run a fair risk of destroying the fiberglass section of sucker rod. My best guess is that at close to 300' the weight of the rod is deforming the metal screw thread or sleeve a bit.
I find this my biggest critique of the Simple Pump in a deep well application. Maintenance is difficult, and in my opinion, you will likely destroy some portion of the sucker rod when pulling the pump bottom for maintenance, presumably every 5-10 years. This and the need for a lot of rigger time while you fiddle with the sucker rod to unscrew, makes maintenance an expensive proposition.
Now, we were at 270' of drop pipe, and with a little initial priming, had water at a very reasonable manual pumping effort given the 180' water level depth. My ten-year-old daughter could work the handle. This is one AMAZING bit of technology.
As a hand pump, especially for a well that is less that 150' deep, I can say without hesitation that the Simple Pump is a great solution.
For deeper wells, in addition to the stressful installation of the heavy pipe and rod, a lot of fiddling was involved to get the stretchy rods adjusted correctly. I felt this was quite dangerous work to do. My fingers felt in jeopardy when lifting the weight of that rod to do the final adjustments at the pump head.
So at this point, we have a working hand pump pulling water easily from near 200 feet deep. Very nice.
Next comes mounting the motor and hooking it up to direct PV.
The solar electric system that had been specified was direct PV, a 210W/12V panel, with a Linear Current Booster that promised to run the pump motor during the sunny part of the day -- 10AM to 5AM roughly. The draw depth of 180' was within the capability of the motor.
We hooked up the 12V 1/5 HP DC motor, set the pump arm lever to the innermost setting (lowest flow, least work) turned it on, and... nothing. Went home, thought about it, and pow-wowed with the manufacturer and solar representative dealer who both were super responsive and patient. Patience on their part was important, because I was more than a little frustrated and stressed at this point.
Came back and turned the motor on, and voilà, it pumped. But no water came out.
Set it to the second cam setting on the pump arm and turned it on and the motor stalled.
Back home to confer with the manufacturer. Out of spec sucker rod stretching was a possibility.
Back again to the site. On the second cam setting, I turned the motor on, and this time the motor ran, and even pumped a little water. Then it stalled. I could manually assist the pump by pulling the arm and the motor would just make the complete stroke. Output was perhaps 1/16th GPM. This was at the height of sun, at about 2PM. Back to the first cam setting and the pump ran, and a tiny trickle of water came out. A little cloud floated by in the clear blue sky and everything came to a halt. The pump would not restart by itself after the cloud passed.
Winter arrived and I had to put the project away until spring. I am happy to say that Gary and Ron understood the long timeline, and were willing to work with me for the duration. I've never experienced that with a retailer before... usually after a month you are on your own.
Having time to think on this problem over the winter and consult the manufacturer resulted in us deciding that the direct PV was not providing enough amperage to run the motor under the load. The motor has a 25 amp fuse, and we were not burning that out, so seemed to be within the capacity of the motor. I had no amp meter so could not measure direct PV output, but that was our hunch. Sucker rod stretch was ruled out at this point.
When I returned in the spring, the pump behavior was mostly the same.
One thing I noticed, which was great, was that the pump held prime over the winter; from late November to March.
However the on-off switch was not operating smoothly. Could this be the problem? Yes! Or at least part of it. The switch contact was intermittent. Simple Pump sent a new, more robust switch. On-off and intermittent circuit operation was now eliminated as a source of trouble, but I still could not get the motor to do enough work to pump more than a trickle of water with direct PV.
As a test, Ron Castle, the very helpful and patient solar rep (Sunshine Works, http://sunshineworks.com
) suggested that I run the simple pump motor directly off my car battery using jumper cables. Half a gallon a minute water output and the motor chugs happily away! Great!
The next step was to add a battery and charge controller to the mix. In retrospect I believe I made a bad mistake not going this route in the first place. I think battery storage is essential for anyone using the Simple Pump in a deep well situation. I was right on the margin with direct PV.
I went through the process of learning how to size a battery array, and that is detailed earlier in this thread. The forum members here were ever so helpful in helping me to understand this tricky multi-variable calculation.
And now the pump works!
Next problem... The pump ran at the 0.5 GPM setting for about an hour, and then blew the 25 Amp fuse. Ugh.
Consider the well flow rate of 0.5 GPM that I asked you to keep in mind at the beginning of this post. It turns out that the well flow rate is something less than that. Probably on the order of 0.35 GPM.
The manufacturer suggested this was perhaps the problem all along. The pump was drawing water faster than the well can replenish and even though I was intaking water at 270', I was lifting from, presumably, 180'. For this motor, that is fine. More than 200' of lift is not (see 48v solution now offered by Simple Pump).
I was able prove this was the case using the Charge Controller load amp meter. Pumping started at 11 amps on the draw. After a few minutes I could watch it creep up, 14 Amps, 18 Amps, 24 Amps, and at 25 amps, the fuse would blow.
To remedy, I needed to decrease the pumping rate. This is done by adjusting the radius of the pump stroke. I backed the pump arm off one hole, to the center of five holes, and now it seems to pump just fine, at somewhere around 0.4 GPM. I've pumped for three hours now, and the amperage draw seems steady. The well recharges, just a little slower than I thought and that made all the difference.
Would I choose the Simple Pump again? I don't know if it really is the best choice for a deep low flow well. I think the GrundFOS SQF-2 or SQF-3 and some sort of DC timer arrangement may have been more straight forward, and certainly more serviceable by local riggers. Theoretically, I could have taken advantage of maybe 75 gallons of reservoir in the column. The GrundFOS pump and copper was MUCH more expensive (pump alone is over 3K), but I may have spent well over that amount in time installing, adjusting and troubleshooting the Simple Pump. Solar costs probably would have been similar.
No doubt there would have been a huge learning curve with the Grundfos too.
The question becomes how long can I go without maintenance; which consists of pulling the heavy drop-pipe, potentially breaking sucker rods in the process, and doing the very straightforward job of servicing the pump "O" rings? How long would I have to keep riggers onsite or callback? Will the motor be reliable over at least five years?
I'll keep this thread updated with long-term performance. Again, I think the Simple Pump is a great hand or motorized pump for wells under 150'. It certainly is a working solution for deeper wells, with the main issues being difficulty and cost of maintenance.