If You Give a Person a Solar Water Pump…

For the past few years solar water pumps have been gaining momentum as the answer for rural villagers’ pumping needs.  If you’re a regular reader of articles at HydrateLife you’ll know that I am a huge fan of technologies that are sustainable, simple, and appropriate for the location and users.  As solar is seemingly at the opposite spectrum of these simple technologies, I was interested in looking at their feasibility in rural areas of developing countries.  Would someone be better off with a simple pumping technology such as a treadle or rope pump, or with a solar pump? What I found was surprising, and opened my eyes to the possibilities of solar pumping.

First, let’s take a look at the different components of a solar powered pumping system (in this article I will be focusing specifically on solar pumping systems for wells).  During my research I was surprised to find that there are only a small number of components required for one of these systems.  In order to pump water you need somewhere to get water from.  This means your first step is to dig a well to pump from or find one that already exists.  Once your well is constructed you can install the rest of the system; this will include solar panels (photovoltaic (PV) cells), a pump controller, a submersible pump, wiring to connect everything, and piping. Batteries for backup power and a storage tank are optional equipment.  However, without battery backup power you cannot pump at night or during cloudy days, at least with most systems (manual devices can be set up to pump water during the night or cloudy days).

Although there are not a lot of components these systems have a relatively high initial cost.  I did a quick internet search and found a couple of different systems to give you an idea of the costs.  For $455US you can get a solar pumping system that will pump 4.5 GPM (17 LPM) at a maximum depth of 8ft (2.4m).   For this price there is no battery backup included, meaning all pumping will need to be done during the day.  If you move up to $1725US you’ll get a system shown below.  This system can pump deeper, up to 230ft (70m), but doesn’t pump as much at 1.6 GPM (6 LPM).  The particular system I was looking at included a 3-day battery backup which had a 4-year battery life.  Also, it was limited to a running time of 5 hours per day (I’m not exactly sure where this limit comes from).

There are a number of different systems and different configurations that can be bought to meet the user’s specific needs.  These two systems are just examples, and prices can run far higher than these. Plus, you have to take into consideration that this is only the cost of the parts.  Depending on where you are in the world the cost to get the parts to your site can be very high, and then you have to pay someone to install the system.

Recently, the Indian Ministry of New and Renewable Energy introduced a program to install 50,000 solar pumps, 20,000 of which will be installed in rural areas.  The system will include a storage tank and piped connections to each household.  It will not include the cost for digging a well.  Where available, an existing well will be used, and if there is no well there will be additional costs to dig the well.  The cost for a system for 250 people is $8,000.  This cost isn’t mind blowing, however, you have to take into consideration that they’re ordering 50,000 systems, so they’re probably getting a better deal than if you were only ordering one.  I found a source that said a system for 500 people could cost up to $34,000US.  WOW!

Saying that, there are organizations that are working to make these units more affordable, however, at this point in time they are still fairly expensive.  One organization, Pumpmakers, is providing the construction plans needed to build their system so that people can build them on their own.  This is a good idea, however, it takes a certain amount of skill and access to the parts in order to be realistic.  And you still need the money to buy the parts.

Now we know that initially there is a high cost which isn’t great, but what about the sustainability of the system in the long term?  To my surprise it seems like these systems are very sustainable.  One of my main problems with moving away from simple technologies is that if you have a complicated (technologically advanced) set up and something breaks then the users are out of luck for a while, if not for a very long time.  I’ll talk about this a little more later on.

What I have found is that solar powered pumping systems are very reliable, and require little maintenance.  Basically, the panels need to be cleaned every once-in-a-while, and the piping and storage tank need to be checked occasionally for leaks.  Maintenance, as far as replacing parts, is practically non-existent as long as the pump or controller doesn’t fail completely.  If they do, you’re looking at substantial costs.  This does not include systems with batteries, which will need to be replaced every 4-6 years.

Typically, assuming there was no default in the components from the factory, the system components have a long life.  The solar panels should last 20-25 years if they are cleaned regularly, and aren’t broken by some outside force such as a tree branch falling on them or hail.  The pump and other components can be expected to last at least 10 years.  Pretty good, but not perfect.

This goes back to my issue; what happens after 10 years when things start failing? If a community uses a simple pumping system that they built themselves then they can repair it as needed.  But with this type of system they’re down the well without a ladder once the components start failing, which is catastrophic, even if it has lasted for 10 years.  So how do we get around this?  Whether these systems are installed by a government body, by an NGO, or another type of organization, a plan has to be put in place to regularly check on the system to make sure it’s functioning, and to repair/replace parts once problems start to arise.

This isn’t necessarily a hard thing to do, and it can actually be very beneficial to the local community. One option is that the organization that installed the system can train someone from within the community (or from a nearby community) on maintaining and repairing/replacing the equipment. This could even be turned into a business that employs multiple people and visits a number of communities on a regular basis.  However, difficulties could arise due to the fact that some of these communities are very remote and not familiar with this type of technology at all.

If the organization that installed the system is a local organization then they can provide the manpower needed to maintain the systems, and they will already know how to repair and replace the parts since they were the ones that installed it.

This all brings up one more question: who’s going to pay to repair or replace parts?  Again, there are a couple of options.  If the organization who installed the system paid for the initial costs then they may have the means to provide the parts to the community at no cost.  That would be great, but how do you let the organization know something has broken if you’re in a very remote area?   Another option would be for the community to raise the money on their own.  Members of the community could pay a small fee for the water being provided, maybe on a monthly basis, and that money could be held in an account for future maintenance of the system.  However, then you still have to find the parts.

With these suggestions I am just scratching the surface.  These are complex problems that have a number of different solutions.  Further, a solution may work in one place but not in another so it may take several different plans for different locations.  The one thing that needs to be common in any solution is that there is a system in place to monitor the condition of the systems on a regular basis, and that is able to quickly provide the parts and labor required in case of a failure.  This way no one finds themselves with an unusable system and no water.

There’s one last point I want to make since I’ve been promoting simple technologies a lot.  I understand that with very deep wells simple technologies may not make sense (or even be possible), and in that case traditionally diesel engines have been used to provide the power.  This brings up a whole new debate: diesel vs. solar?  You kind of end up with the same problems though.  Even though diesel engines are bad for the environment, and you have ongoing costs of fuel and maintenance, it may be the better option in some cases because a lot of people are familiar with how to maintain them and spare parts are easier to find.  Also, the initial costs are a lot lower.  However, over time the costs to maintain a diesel engine can pile up (and studies I’ve seen show they can end up surpassing the initial cost of a solar system).  The choice of which is better depends on a lot of factors, and there is no right or wrong answer.  The answer will be different for every situation.

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I write these articles to help share information, but also to educate myself. I learned a lot this time around.  I was pleasantly surprised with the information I found about solar water pumping systems.  I had no idea the components were as reliable as they are.  However, I’m still not 100% on-board.

I still believe that simple technologies are the way to go.  Even with a good monitoring system in place, if part of the solar system break the community will be without water for at least some amount of time.  If the water is being pumped using locally available material with locally known practices then the flow will never stop.

Further, simple technologies are dependent on man or animal power, not the sun.  As the lengths of the days and the intensity of sunlight change throughout the year so does the output from the solar system.  The chart below is from a case study done with a solar water pumping system in the US state of Texas.  As you can see, the output changes with each month.  This makes the system somewhat unreliable. Also, in this study they were constantly adjusting the controller to maximize the systems efficiency, something that would be difficult to do in a remote area.

After writing this I’m leaving with a better knowledge of solar powered pumping systems and a more open mind about them. Yes, I’ll say that in certain situations solar is the way to go.  However, as with a lot of things in life, there is no one answer to the question of how to best get water out of a well.  There are a lot of factors that go into answering that question, and, as I’ve said, the answer will be different for every situation.  But in order to start answering the question you need to know what options are out there, and now we’re all a little bit more capable of doing that.  As always, thanks for reading!

Sources:

Colorado State University – Solar Powered Groundwater Pumping Systems by R. Van Peltm, C. Weiner and R. Waskom

20,000 Solar Pumps For Drinking Water In Rural India by Anand Upadhyay

Solar-Powered Groundwater Pumping Systems for Domestic Use in Developing Countries by Ryan Van Pelt (click on first link)

A Cost and Reliability Comparison Between Solar and Diesel Powered Pumps

Rural Water Supply System: NSP Solar Pump

Solar Powered Water Pumping System by Yuvvraj Singh

If You Give a Person a Solar Water Pump…
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6 thoughts on “If You Give a Person a Solar Water Pump…

  • December 7, 2014 at 2:04 am
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    Thanks for a great article! My understanding is that if you have a large enough storage tank at some height (for a gravity fed distribution system) you don’t need batteries. Just ensure you can store enough water to get through night/cloudy days. Recommended 3 days worth.

    Reply
    • December 11, 2014 at 9:38 am
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      Yes, I believe you are correct. 3 days is what I have seen recommended also. Thanks for reading.

      Reply
  • March 31, 2015 at 12:25 pm
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    I want to doing this one as a my final year project please tell me where should I start. and its how much costly

    Reply
    • May 29, 2015 at 11:08 am
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      Hi,

      Let me know how I can help you with your project. There are links at the end of the article to the sources I used to write the article. That would probably be a good place to start. The cost for solar water pumps varies depending on the size and capacity. There is a lot of information out there on the internet about solar water pumps.

      Let me know if I could help further.

      Reply
  • May 11, 2017 at 8:15 am
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    Dear Brian
    Nice article. We had some good papers on solar pumping at last year’s RWSN Forum – including a great overview paper by UNICEF https://rwsn7.net/content/groundwater/

    One point I would pick you up on for further investigation, if you are interested, is the implications for groundwater resources. Handpumps – even lots of them – barely impact water table levels because the quantities are small. Cheap energy (either solar or subsidised) suddenly makes it possible to abstract a lot more water. This has implications for the borehole design if a solar pump is being retro-fitted onto a handpump borehole, and it has implications for groundwater resources management. That said, for many areas I think solar pumping is the future.

    cheers

    Sean
    RWSN/Skat

    Reply
    • May 22, 2017 at 4:13 pm
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      Hi Sean,

      Great point about the switch from handpumps to solar pumps. I hadn’t thought about that. And thanks for the link. I’ll be sure to give it a look.

      Regards,
      Brian

      Reply

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