My Solar-Powered Dankoff Slow Pump System – Part 1, by Tunnel Rabbit

This article is essentially a poor prepper’s guide to the affordable solar-powered Dankoff Slow Pump. In my case, I put together a portable DIY solar water pump for only $1,500, including photovoltaic panels.

Water is life and the more ways we can get it, the better. For surface water, the Dankoff Slow Pump is what I would use in many situations.  There are so many pumps to choose from, but to make a simple and easy choice; if I could only afford the least expensive, and most reliable solar pump for all surface water sources, it would be this pump. I have the Dankoff Model #1308-12, but I now recommend the #1303-24 as the best for the money for most folks, for several reasons. I learned by doing, and found that I should have got the #1303-24 instead. Learn from the mistakes of others, we’ll likely not live long enough to make all of the mistakes ourselves. [JWR Adds: Dankoff also makes a 48 VDC model.]

That said, the Dankoff Model #1308 is actually not all that bad a choice. It works reliably too, but it only pumps about half of the water volume of the #1303.  The #1308 is a better application when used for pumping longer distances, or up mountains as high as 450 feet. And because photovoltaic panel prices have dropped significantly since I purchased the #1308, the #1303 now makes more sense. I have also built many ram pumps that perform well in certain sites with enough ‘head’, but the Dankoff Slow Pump will pump from all surface water sources.

Ram Pumps?

A good quality ram pump will cost about the same, plus the galvanized drive pipe, stand pipe, long feed pipe, and fittings, but it requires flowing water, and a minimum amount of head, or drop in elevation, given a specific lift, or distance to be pumped. However, ram pumps are not a plug and play device, but requires some real engineering to get it right. It is technically more difficult.  If you have the right kind of water source, then the ram pump could be a much better choice. The Dankoff Slow Pump is, fortunately, much easier to use. It can be used for all surface water situations.  The YouTube vlogger Engineer775 has many excellent videos on the development of many types of water resources, including the Dankoff Slow Pumps that can be used for creeks, ponds, springs, and cisterns.  He prefers these over other types of pumps for these situations. The slow pump is the best ‘tool’ for the job when it comes to surface water that is no lower than 15 feet from where a slow pump can be mounted.

Seeing is believing.  Here are links to some of Engineer775’s Dankoff Slow Pump Installation videos:

My purchase was made prior to his jump into these, so we did not have his expert opinion to draw on. It turned out to be a good choice. He does this pump justice, whereas I cannot. This is only an introduction, a parts list for a low cost system, and a walk through on how to estimate the pumps potential output to see if it might be a good choice for your situation.

A Bare Bones Installation

I believe most readers can purchase, and install this for no more than $1,500.00. If the price is right (affordable), can you handle the installation? Let’s find out, so you don’t waste your time reading this to only go away thinking it is too technical. It is actually stupid simple. Here is an attempt to describe it. The pump has a red wire and a black wire, the red wire is the positive one.  We are going to connect the pump directly to two 12vdc photo voltaic panels connected in series, so that together, they produce 24vdc, with only a common 10 amp spade type automotive fuse, and a 12vdc automotive 10 amp (or heavier amperage) switch in between.

First wire up the panels. Connect panel A’s black wire to Panel B’s red wire, then connect panel A’s red wire to the red wire on the pump.  Then connect black wire from panel B to the black wire on the pump.  Install the switch at the pump end, and the fuse at the panels.  Done. Of course there will be a fairly long run of wire in between. If these instructions did not intimidate, then you too can install this pump, and should read further to discover more.  And just in case the reader would like a sneak peek, here are Dankoff’s schematics in the Dankoff Installation and Service Manual, but don’t let that scare you off.

Keeping It Simple

We can keep the job simple, and the price lower by directly connecting the pump to the panels, and to avoid the complexity, and big expense ($700) of a linear current booster (LCB), for a relative small reduction, if any, in performance by adding an additional set of two 12vdc 100 watt panels for the cost of only $250 (price includes shipping), instead of the LCB. As we will latter see, having 400 watts powering the pump is not only much less expensive, it will out perform the more expensive option, that is the LCB.  A LCB operates in a similar way that does an MPPT charge controller, it converts available voltage into amperage.  With 400 watts to compensate, and exceeds the output of a LCB using 200 watts, means you can forget about the LCB, and it’s price.

I also want to point out that the LCB is the only electronic device in the system, and would be the most sensitive component, and possible point of failure over time, regardless of EMP or CME threats. And we may not need the maximum performance of the pump, and could start out with only one set of two 12vdc 100 watt photo voltaic panels, instead of four. We would also use common wiring, and in line fuses (12vdc, 10amp ), instead of circuit breakers, another big savings.  Instead we could use a 12vdc automotive toggle, or ‘rocker’ switch. It would be a ‘bare bones’ system, but it could pump enough water to grow at least one quarter to one half acre of food in most situations to feed a family of four or more.  It could get us into the long term water pumping business, the food growing business, whereas a more expensive, and technically complex Dankoff Slow Pump installation might be prohibitive.

By The Numbers

This solar pump recommendation should be in reach of most folks, financially and technically.  Engineer775’s excellent, first class installations, might cost $4,000, or more, just for the components!  If one needs to hire an expert to install any system, the price just went higher, and possibly out of reach.  We always have more essentials to buy, and a penny saved is a penny earned.  And water for the garden makes food. Water = food = future. The regular pepper can get it done for the least amount of money. It is easy to forget that water should be a a top priority. A $1,500 solar water pump has a good risk/reward ratio, because water is life.  It is well worth investigating.  It will pump water, and hopefully all that you will need to feed a family. If it does not pump as much as needed, then adding a set of two 100 watt solar panels might necessary.

Looking at the manufacturer’s pump performance chart, and locating the specified maximum 204 watts listed, the 1303-24 pump is rated to lift water up to 240 feet of head, and pump 2 gpm (gallons per minute). At a much lower lift, or between 20 to 80 feet high, it requires less than 100 watts to get that job done. We will be using two 100 watt panels wired in series to make one 24 volt panel.

Use inexpensive 1/2 poly pipe to make the run to the garden, and then, garden hose where it’s needed.  Garden hose is not cost effective in long runs of hundreds of feet, or where high pressure occurs in the line. Half (1/2) inch black in color, semi ridged poly pipe is the most cost effective, about $0.35 to $0.50/foot and it will handle the maximum pressure the pump could create when pumping great distances, or to the pump’s maximum rate height, in this case, 240 feet.

I would expect the #1303-24 pump to produce enough water for a 1/4 to 1/2 acre garden with two 100 watt panels co-located 100 feet, or more, above the water source. This assumes that one is growing the thirstiest crop, beans that require 450 gallons per day per acre during the driest part of the season.  Based upon the University of Montana Agriculture department estimates of water consumption for particular crops they studied, most crops use less.

For Greater Output

To increase the pump’s output (more current, but at the same voltage), use an additional two, or even four 100 watt panels ($250-$500), or install a linear current booster (LCB) for an extra $700.00. Additional panels can be to be added to a solar system, or become a solar system during the winter when not in use. The pump can also be run directly from two 12vdc batteries wired in series, or from a solar system of the same voltage.

Major components for this system are:

  • Dankoff Slow Pump, Model 1303-24       $595
  • 4 each, 100-watt photovoltaic panels      $384
  • Dankoff DRS2500 Dry Run Switch           $80
  • 250 feet of 12 AWG wire                          $66
  • 500 feet of 1/2′ poly pipe                          $41
  • Dankoff 11003 Float Switch Kit, 10 amp. $59
  • 1/2 inch check valve                                   $9
  • 1/2 inline water filter, Dankoff                   $86
  • 1/2 inch foot valve                                     $15
  • 10 spare water filter cartridges                  $70
  • Misc. fuses, connectors, fittings, etc.:        $95

Total:  $1,500. (Needless to say, you should shop around for the lowest prices.

[JWR Adds: Several SurvivalBlog advertisers sell PV power and pump system components. If you buy from them, then please mention SurvivalBlog.

It is also noteworthy that Dankoff Slow Pumps has been in business for more than 30 years. They are made in Oklahoma. The company was founded by Windy Dankoff— a legendary figure in the PV world.]

Here is a Dankoff Slow Pump Performance chart. This chart indicates a pump model’s output in ‘gpm’ (gallons per minute), and the distance in elevation it will pump upward in feet, given a photo voltaic output in watts specified in the chart. Note that this chart is only a general guild.  Often the “real world” results are less than expected, because of the wide variation in actual solar conditions, or what is called, isolation. (Not to be confused with ‘insulation’!)

(To be concluded tomorrow, in Part 2.)

 




9 Comments

    1. Thanks! Always looking for another way to pump water. Added that to my collection. I could have wrote about radios, guns, ballistics or other, and did a bit the other day, but there is plenty of that material available already, and water is right up there with ‘security’. ‘Security will be ‘job 1’, but no water, no life. After years of looking into the topic, the Slow Pump, is still at the top of the list, and it can go with me should I have to leave. If forced to leave, the ability to grown food becomes even more important as the bulk of one’s food storage may have to be left behind, or is lost. It is simple to use, compact, lightweight, and adaptable to most situations where one may find themselves, and there are several ways to power the pump, small gasoline generator, bicycle/alternator, bicycle/ treadmill motor(generator), batteries, and directly from a standard solar system. Mine is stored in my RV ready to go.

      No, pumping water is not as interesting as other topics, and the Dankoff Slow Pump is rather boring, but growing food, and watering livestock could be interesting. If one has a well, then there are better pumps for that job, but the Slow Pump can be used for that purpose as ‘well’, should the casing be 6 inches, or larger in diameter. It could be a back up, or alternative to an existing pump. If using P.A.C.E. (Primary, Alternative, Contingency, and Emergency) in your planning, it fits in any of those categories. After years into the topic, I do not know what other water pump could be a better choice. And that makes the pump particularly interesting to myself. But I could talk about how to turn standard cup and core lead bullets into anti-material rounds if you like. That could be interest too, but it would not as important as pumping water.

      1. Well written article, Tunnel Rabbit. Good to link to Engineer775’s videos/channel, as he has quite a bit of experience with installing water pumps. [And using Solar Power too] … It’s always good to learn from someone else’s experiences.

  1. Thank you for your kind comment, yet the credit should go to JWR as he had to clean it up. I am not, or never will be, the author of a best seller, or any book. I didn’t write it to win any prizes, but to get this information out there. As we see Engineer775 finds the pump to be useful, and he had done a great job at proving to be useful, and continues to use it in new installations, even after all these years, this pump is without a doubt useful, especially in mountainous water ladened regions, such is the American Redoubt. The pump is under-appreciated, but as in the case of Engineer775, there might be someone else who will run with it. If there is, rumor is that there is a big price increase expected in Oct. 2019, upwards of 40% on the pumps, upwards of $240 USD, or Federal Reserve Notes , and based upon a retail price of $600.00. That is significant.

    The reason the LCB’s (linear current boosters) are so high in price ($700), is that the single manufacturer for Dankoff LCB’s suddenly went out of business, leaving a very short supply. The remaining units are therefore priced extraordinarily high. There is another manufacturer Beta testing, and prices might be reasonable, and in the $300 range once again. Call Dankoff to see if they can make a recommendation. It is difficult to fully compensate for the lack of a LCB, yet four 100 watt panels should adequate, and six 100 watt panels would not be a excessive, and would improve the performance yet further. Because it freezes in Montana, I would use the pump only seasonally, or for about 4 months out of the year. Brushes are said to last 5 years with continuous use, and the pump head, 10 years. Therefore, if used only seasonally, the brushes may last up to 15 years, and the pump head, 30 years if fed only clean water. In the case that the pump is only used seasonally, the extra panels could be added to the PV system for the house. Or one could run power out to the pump from the ‘house’ solar system saving money there. The advantage to running off, or with the assistance of batteries of a PV system, is that regardless of the weather conditions, the pump will run continuously, albeit 20% slower, it should pump closer to it’s rated capacity, or 2.5 gpm less 20%, if the TDH (total dynamic head), or line pressure is less than about 100 psi, and it likely will be in most installations. The brushes may actually last longer too. Knowing your options can make a difference.

    A good way to make a rough estimate of the amount of water needed per day, is my own formula based upon my garden’s consumption during long hot and dry summer days. There are many variables, and no constants, such as wind, soil type, plant type and stage of growth, so this is only an estimate. Take the garden’s square feet, and multiply by 0.15. That would be the minimum capacity I would want. If I had a garden that was 50 x 50 (almost 1/4 acre), there would be 2,500 square feet x 0.15 = 375 gallons per day, or 1 gpm for 6 hours. The 1303 can potentially do twice that, or more. More is always better. And I would have as much water storage to cover several days if I could, especially if it was operated without a LCB, as the pump will not produce as well during overcast days. Have the ability to store excess production that occurs on cloudless sunny days, if at all possible. Of course a garden would not need as much water during cloudy days, but it may need extra during a heat wave.

    There is more I could say about it, or ram pumps, yet if there is no interest….? Please feel free to ask any question. If you can afford an expert, contact Engineer775 though his website, PracticalPreppers.com. His name is Scott. If there is a next time, I might do something that is of more interest, yet practical. I could talk all day and night about radio, or ballistics stuff, but that is well covered already. Learning how to manage resources, and the logistics side of the house, is actually more important than the bang- bang side. No, MRE’s will not fall magically from the sky, and there will be no food-fairy that magically appears, and kicks it off the truck. Besides, I need to learn more about water and gardens, and by writing, I learn. Thanks for listening.

  2. Your article is excellent. You made one conclusion regarding the size of a garden measuring 50 feet by 50 feet, that it would comprise one fourth of an acre.

    A square acre measures 208.7 feet by 208.7, or 43,560 square feet. As you correctly stated, a 50 by 50 foot garden is 2,500 square feet. Comparing your 50 by 50 garden to an acre would require dividing 2,500 by 43,560. The result is .057, or 6% of an acre. Math can be confusing.

    1. Thanks for catching that. Unfortunately my email has not been sending a notice when there is a reply, and I missed your post, and continued the error of comparing my example garden sizes (50′ x 50′) to 1/4 acre.

      Fortunately the analysis was only flawed in that regard, as the basic math accompanies the argument for clarity. Yet the error is important in as it is used in an old ‘rule of thumb’ that a “1/4 of an acre can feed a family of 4”. Fortunately I found, and used a real world example as a benchmark in the last installment that calibrates, providing a comparison that compensates for abstractions, and error. Stated that my estimates are, “unsubstantiated”, and “rough”, and based upon my crude experiment, and indeed they are, yet I found it helpful as another measure provided by the University of Montana (450 gallons per acre), is lower than my home derived estimate. It is an attempt at verification. I am a student of the Scientific Method, and welcome peer review.

      Any farmer or gardener knows well that there are too many variables to be precise, that we may strive only to be accurate. Who knows what the weather will be! I suspect, but do not know what it will be in the near future, perhaps wetter and colder? Thankfully the math preserves the analysis. This is why figures should always be included, ad nausem. It is confusing, but fortunately the error was not at the heart of the analysis.

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