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.
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:
- Spring water up the mountain – Part 1
- Spring water up the mountain – Part 2
- Slow Pump Installation
- Finally! SOLAR Slowpump in a shallow well
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.
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.)