Solar pumps - the potential of a technology and realities on the ground

Photo: Steve Fletcher, University of Wyoming

The concept of using solar energy - particularly photovoltaic (PV) technology - to pump water is not new. Academic papers have been praising its potential for decades, and programs to introduce the technology abound.

In India, several states have run subsidy programs, resulting in seven to eight thousand solar pumps installed in farmers’ fields. But that number is miniscule compared to the 9 million diesel pumps in use, mostly because uptake of solar pumps in the un-subsidized private market has been almost non-existent.

One obvious reasons for this is purchase price.

As we have seen in the previous post, diesel pumps are cheap, anywhere from 10,000-30,000 rupees (160-490 USD).

A comparably sized, 2-3 HP solar pump system sells for no less than 200,000 rupees (3,300 USD) - and often much more. This is more than ten times the price of a Honda pump. That's quite a sticker shock for even medium-size farmers.

Of course, solar pumps have one big advantage: they have almost no running cost. Solar pump owners don't spend anything on fuel (sunlight is free) and hardly anything on maintenance (zero for panels, and near zero for modern electric motors). The life expectancy of solar panels is 20+ years, the electric pump will last at least 10, and likely more. So once the farmer has made the initial investment, his water is basically free.

In the long term, the cost advantage of solar pumps is overwhelming, and the falling cost of solar panels continues to reduce the time to amortize the initial expense.  Today, depending on how much he pumps, a farmer can recover his solar pump investment in as little as 2-3 years; from then on the water for his field is free, and any water he doesn’t need he can sell to his neighbors at 100% profit.

But despite this, diesel pumps continue to dominate: primarily due to credit availability, and farmer capacity for risk.

Most small farmers don’t have enough capital to buy a solar pump, forcing them to take out a loan to finance the purchase.  But getting a loan is difficult, particularly for such a large sum and from rural banks that remain reluctant to finance “exotic” technology such as solar pumping.

Investing in a proven diesel pump is both cheaper and easier in terms of finance - rural banks know the technology and have been lending for this for decades.

Even if farmers are able to secure a big enough loan, they have to put up collateral, which is almost always their land. If the pump fails to perform as promised and a poor harvest results, it can mean defaulting on the loan and losing their farms.

Solar pumps remain a fringe technology, unproven to the farmer. Literally “betting the farm” on this is a huge risk to take, and recent experience has been a bad precedent. Many farmers trusted salesmen peddling expensive genetically modified seeds; the seeds failed to live up to expectations and left the farmers in massive debt. Many lost their family land as a consequence. Farmers have been burned before and are understandably reluctant and distrustful.

This mixture between credit scarcity and understandable aversion to risk has been a potent brake for solar pump adoption.

And there are other problems, such as the lack of portability, and weather risk. All these issues combined have slowed significant uptake of the new technology.


As always, we would like to hear your take. Please let us know in the comments below. Remember, you need to register with Jovoto to comment. Thank you!


Most of the farmers are not confident regarding this technology and maybe because they don't know that much examples, other villagers that have such pumps. Through some forums I found that some farmers are buying old solar panels to do the job. But live cycle is super small comparing to new ones and they don't have that much power. Nevertheless, the financial risk for them is smaller in a short term.


PS: And yes, whatever comes out of this contest, MUST be cheap enough. There are quite enough expensive solar pump systems out there.


Tania, would you be able to share some of the forum links referring to the farmers buying old panels? Looks like an interesting case to look at.

Regarding examples for farmers, that is why we require a winning pump design be portable, so it can be transported easily, ideally on public transport, for demonstration in village markets. Do you think any other attributes would help in "demonstrability"?


Could we have these solar powered pumps selling excess electricity one day ?

India plans to spend 6 billion euros ($7.9 billion) to build an electricity grid to evacuate power from wind and solar plants that have more than doubled in capacity in the last five years.


I think the power generated from these pumps, considering they need to be cheap and compact, will only be sufficient to power smaller appliances, like reading lights, charge cellphones, also because of the battery issue, no?

But we do hope farmers will use them to sell excess WATER to smaller neighboring farms who don't have a pump. Feasible?


Coming to the rescue of the drought-hit farmers reeling under frequent power cuts and diesel price rise, the state government has decided to put in place solar irrigation system in villages.To begin with, 40 districts have been chosen where 400 solar irrigation pumps would be installed in villages facing acute shortage of irrigation and drinking water. Entrusted with the task, the Non-conventional Energy Development Agency (NEDA) has already installed about 150 solar water pumps.One of the unique feature of these environment-friendly pumps is that they are more powerful than the diesel ones and can pump out water from as deep as 200 feet and up to 12 hours at a stretch. NEDA has successfuly installed two such pumps in rocky terrain of Sonebhadra district.Costing about Rs 3 lakh, these portable solar water pumps can be taken anywhere and its solar panels are maintenance-free for about 20 years. The Centre has already sancntioned Rs 12 crore for the scheme. At the moment, the state is charging about Rs 70,000 from the beneficiaries.


This is very interesting! Could you share a link with more information on that pump design? Especially the portable part is of high interest for us, no? We are shooting for much cheaper (1 lakh) to be able to do without subsidies, but maybe the solver community can get inspired?


A subsidy on the purchase of these pumps can also lure the farmers to go for solar pumps, like for example the Punjab Government has already announced 40 per cent subsidy on purchase of solar pumps to farmers for using these pumps for irrigation.


Subsidies are nice to have, but I doubt the government of India, or the states, can pay enough to subsidize millions of pumps? They are reducing diesel subsidies because money is short, only to spend billions on pump subsidies?


I'd wonder if they (Greenpeace Judges) would be amenable to a solar/renewable which had diesel as one of the alternative fuels?


I think that could be a very good solution. Running mostly on solar, with diesel backup? Solves the weather risk and would help farmers trust. As long as it can be done within the price requirements, very interesting.

PS: The judges are mostly non-Greenpeace, only Sven and Samit are GP, the others are independent experts. :-)


Greetings from SolarFire.

Over the past we have been crowd-funding our technology and released a lot of open source material on our website

With our low-cost, simple-to-build solar collectors we can provide heat. A steam engine could transfer the heat into motion, powering a pump or an alternative "breather pump" could be developed, that has no moving parts -- I will talk this over with my team a partner who told me about this idea. The aim could be to stay below 20k Rs.

We are very interested in making solar fire technology more accessible to people. With your fund we could invest in developing the heat-to-pump application.

India is a great place for solar thermal energy use. I spent two years in Maharastra 2006-08. Simpler applications could be for roasting, distilling, wool-cleaning, cotton dying, food processing such as evaporating and pasteurizing.

I will definitely stay tuned to this project. Let me know your thoughts!

Kind regards,
Urs Riggenbach, Switzerland


Great approach Urs! Would love to have you on board as participant! Have you seen the sunflower pump? Similar design it seems?


The comments on farmer acceptance are very relevant. We find that most farmers will let the innovators prove that the system works before jumping on the bandwagon.


Right! We heard the same in the field visits. So we must be able to demo them, move them around, lend them out, etc. Hence portable, portable, portable, no?


I think the best way out is to use a 370 W submersible pump with high pressure head. It can cost about 3K. A 500 W panel cud cost 20K. Electronics and 1 phase inverter etc 5K. The idea is to do Maximum power point tracking to get out as much solar power out as possible. Small head pumps (even with same power rating) cut off when sunlight reduces , leading to unnecessary waste of solar and downtime.
So total cost cud be under 30K.

A 2 hp diesel pump~ 25 K used for 1 hour is 1.5 KWh which can be generated in 4 hours by the 370 W pump. Hence where DG pump usage is only moderate like 2 -3 hrs /day and the rest of the time is idle it can easily replace it with solar.

@ 2hrs it burns about 2liter fuel or about INR 100/day . The additional investment is recovered in 50 days.

The key is using Hi head pump (though water depth is small) and smaller wattage pumps running for a longer period of time. This optimizes solar panels (biggest component of capital cost) by allowing MPPT. as well pump investment is considerably reduced.

Also it makes it fairly portable for security.

Sounds great concept, join in , lets try to implement.


Hi the challenge details are pretty open ended.
What is the amount of water expected to be pumped out per day ? If a 2-3 hp pump only runs for about 2-3 hours per day then its a different ball game compared to something running for 10 hours/day. If the cost of water by using diesel or solar is turning out to be so expensive perhaps a better option would be to encourage farmers to go for drip irrigation


Also what is the expected water depth from which water has to be pulled ? Based on that everything else can be sized up optimally.

Hi Nahar,
Refer to Project brief, water table is expected to be at around 5 m.


Also, target plot size is 1 hectare. Its always "or better" -- get water from 5m or deeper, water plot 1 hectare or more, while costing no more than 1 lakh. :-)


Yes everything was organized as blog posts so , didnt read the perf. requirements before posting the comments. A 10 m dynamic head 0.5 hp single phase electric pump wud suffice..


Greenpeace had invited me to Bihar last year to install small solar pumps . It gave me a chance to see the local conditions..

I had taken several pumps but they failed to impress local farmers. They were too small., just 0.3 to 0.5 hp. These imported Chinese pumps but were not reliable . I had to think of an Indian pump that would work on solar power.

I am happy to say that I now have a one horse power Indian made pump that runs on 1200 watts of solar panels. It delivers about 8000 ltrs/hr at 10 m head and costs under Rs 100,000/-.

I have installed one in North Bihar for a vegetable farmer .

I am now working on making it portable. A farmer will be able to put solar panels and the pump on to a hand cart or animal cart and take it away to a secure place at night. I have seen such carts in Bihar which are locally made and most farmers have them already.


a question. Is there running water available in any or some of these areas? That could drive a small cheep water powered pump