Solar DC Submersible pumps as an alternate source for irrigation

Our farmers are facing accute water shortage due to irregular and erratic current/grid supply. To mitigate this problem, We have come up with  solar DC submersible/surface pumping solution as an alternate.
Pl. find attached an article on the solar DC submersible pumps.
Awaiting feedback from esteemed members of this forum.
AgricultureInformation_part1.pdf (128 KB)

Hello,

Thank you for the attachment.

I would like to highlight few points here;

A)You have mentioned AC solar water pumping as Rs.5,63,750 @ Rs.161.50/watt as bencmark cost by MNRE, agreed. But the same 5hp as per the same MNRE benchmark costing would be Rs.6,65,000 @ Rs.190/watt. Which implies DC water pumping is costly.Comparing a 5hp AC pump to a 2hp DC pump would not be fair but do you say that your DC pump can discharge more than AC pump for a particular head in m?

B)DC pumps are very sensitive to mud content in water whereas AC pumps are not

C)AC pumps have an option to run on grid/DG in case DC to AC fails or during night times, what contingency do DC pumps have to offer?

D)What is the max head and HP that a DC solution can support w.c.t AC pumps?

E)The water discharge comparison you have taken into consideration is @ 100ft i.e 30m head, which is practically rare to come across.

F) I have a AC pump, face a winding problem or impeller problem, what I do is hire a motor mechanic near by my farm but what do i do if DC motor has downtime? Are these DC motor’s common enough in India and if yes can you point me to DC motor Indian OEM’s?

G) Also please note that pump efficiency can be calculated only by knowing pump suction and discharge pressure,pump flow,motor power,mechanical efficiency of the electric motor, merely putting it as 25~40% efficiency needs a better explanation as to how have you arrived these figures?

Please note, we did recently install a 4hp solution to one of our esteemed customer’s which @ 110m head yielded close to 50000 lpd and now after erecting 6hp pump @ 98m head we are getting close to 90000lpd - on pure solar mode without grid 10 hrs operation.

My point is, AC solar water pump solutions or retrofit models are the best bet.

Regards.

Dear Mr. Sarvana Kumar,

I would like to respond to your post point by point marked in blue colour font.

A)You have mentioned AC solar water pumping as Rs.5,63,750 @ Rs.161.50/watt as bencmark cost by MNRE, agreed. But the same 5hp as per the same MNRE benchmark costing would be Rs.6,65,000 @ Rs.190/watt. Which implies DC water pumping is costly.Comparing a 5hp AC pump to a 2hp DC pump would not be fair but do you say that your DC pump can discharge more than AC pump for a particular head in m?

[color=blue]This analysis is based on annual average of working of 5 hours  with solar retrofit of AC pumps. Please go through the assumptions carefully. You don’t have to assume  5 hp DC pump for current comparison/calculations, for which the discharge would be very high.[/color] I

B)DC pumps are very sensitive to mud content in water whereas AC pumps are not
[color=blue]Sorry gentleman, any pump head operating on DC or AC is sensitive to mud in the water.  You should check with the suppliers who refuse to give warranty if there is sand / mud in the water.
[/color]

C)AC pumps have an option to run on grid/DG in case DC to AC fails or during night times, what contingency do DC pumps have to offer?
[color=blue]We offer AC to DC converters/inverters which allows DC pumps to operate at night times if there is grid supply.
[/color]

D)What is the max head and HP that a DC solution can support w.c.t AC pumps?
[color=blue] Latest DC submersible pumps can draw water from depths greater than 700 feet. Ultimately its economics.[/color]

E)The water discharge comparison you have taken into consideration is @ 100ft i.e 30m head, which is practically rare to come across.
[color=blue]Request you to survey different areas for ground water in different southern states.[/color]

F) I have a AC pump, face a winding problem or impeller problem, what I do is hire a motor mechanic near by my farm but what do i do if DC motor has downtime? Are these DC motor’s common enough in India and if yes can you point me to DC motor Indian OEM’s?
[color=blue]There is no winding in the DC submersible motors, so this problem does not arise. DC motor concept is slowly catching up as this is good option for DDG. Spares are now available. You can contact us for more details. 
[/color]

G) Also please note that pump efficiency can be calculated only by knowing pump suction and discharge pressure,pump flow,motor power,mechanical efficiency of the electric motor, merely putting it as 25~40% efficiency needs a better explanation as to how have you arrived these figures?
[color=blue]The figures are based on inputs by the AC submersible pump manufacturers and our data analysis.[/color]
[color=blue]

Please note, we believe in lower capex and opex i.e. economics which will benefit end customer.  [/color]

Hi,

Good to see your response.

This analysis is based on annual average of working of 5 hours  with solar retrofit of AC pumps. Please go through the assumptions carefully. You don’t have to assume  5 hp DC pump for current comparison/calculations, for which the discharge would be very high.

[color=red]Wonder what benchmark cost from MNRE has got to do with your 5hr assumption.As far as MNRE benchmark costs are concerned DC solar pumping is costly than AC solar water pumping. If you have assumed 5hr/day annual runtime, then can you confirm your statement that a 2hp DC pump @ head x meter will discharge more than 5hp AC pump @ the same head?If yes may i request you to let me know if you can arrange a site visit. If what you are saying is reality, I would love to be trading your products.[/color]

Sorry gentleman, any pump head operating on DC or AC is sensitive to mud in the water.  You should check with the suppliers who refuse to give warranty if there is sand / mud in the water.

[color=red]Agreed. Both the pumps are sensitive to mud in water, but the difference lies in coefficient of sensitivity w.r.t level of mud content.[/color]

We offer AC to DC converters/inverters which allows DC pumps to operate at night times if there is grid supply.

[color=red]Ah. Now i see cost economics getting high.[/color]

Latest DC submersible pumps can draw water from depths greater than 700 feet. Ultimately its economics.

[color=red]You have not mentioned the Indian OEM’s manufacturing such DC pumps and also what would be the cost economics of such high head pumps?[/color]

Request you to survey different areas for ground water in different southern states.

[color=red]I may be wrong but southern state members here would know better if 30m water table is realistic or not.[/color]

[color=red]Last but not the least;

We have a requirement from a customer who needs to pump 90LPM @ 200 m head from a 6" bore.He needs a option to run the pump between solar, Grid & DG. We have already recommended him 7.5hp pump and solar solution @ Rs.7.25L including monocrystalline panels 7500 watts, 7.5hp AC pump controller, Mounting Structure,7.5Hp Submersible pump,200m bore pipes & accesories but he is apprehensive on total cost. What would be the cost of your solution for the above requirement to pump 90LPM @ 200m using a DC solar pumping solution with an option to run the pump between solar, Grid & DG?Please mention your terms & conditions also so that everyone here will be benefited.[/color]

Regards.

Dear Mr. Sarvanan,

You have made this discussion look like a AC versus DC war. A-la- Telsa versus Edison.
Try to see the positives instead of buldozing your views randomly. I think you have misunderstood the parameters in the document and are jumping the gun. I request you to exhibit patience, maturity and give sanity to this discussion. FYI - WE ALSO SUPPLY SOLAR SYSTEMS FOR AC PUMPS.

Now coming to your concerns, my replies are marked in blue coloured font.

A) Wonder what benchmark cost from MNRE has got to do with your 5hr assumption.As far as MNRE benchmark costs are concerned DC solar pumping is costly than AC solar water pumping. If you have assumed 5hr/day annual runtime, then can you confirm your statement that a 2hp DC pump @ head x meter will discharge more than 5hp AC pump @ the same head?If yes may i request you to let me know if you can arrange a site visit. If what you are saying is reality, I would love to be trading your products.

[color=blue]Please Read the document carefully once again. You will get your answers. Our installations have been visited by various officials, professionals and farmers, who changed their opinion after visiting the site. Appreciate if you can contact us to discuss the site visit. 
[/color]
B) Agreed. Both the pumps are sensitive to mud in water, but the difference lies in coefficient of sensitivity w.r.t level of mud content.
[color=blue]
Hello Saravanan, there is no indian pump manufacturer who will give any warranty his/her pump if there is mud/sand in water. [/color]

C. Ah. Now i see cost economics getting high.
[color=blue]It is still a cheaper option.
[/color]

D) You have not mentioned the Indian OEM’s manufacturing such DC pumps and also what would be the cost economics of such high head pumps?
[color=blue]
We are “THE PEOPLE” in this region who should be contacted. [/color]

Last but not the least;

We have a requirement from a customer who needs to pump 90LPM @ 200 m head from a 6" bore.He needs a option to run the pump between solar, Grid & DG. We have already recommended him 7.5hp pump and solar solution @ Rs.7.25L including monocrystalline panels 7500 watts, 7.5hp AC pump controller, Mounting Structure,7.5Hp Submersible pump,200m bore pipes & accesories but he is apprehensive on total cost. What would be the cost of your solution for the above requirement to pump 90LPM @ 200m using a DC solar pumping solution with an option to run the pump between solar, Grid & DG?Please mention your terms & conditions also so that everyone here will be benefited.
[color=blue]
Gentleman, please send me a formal query to our email ID (Refer the document attached). Please enlighten me on the requirement of 90LPM for- number of  hours/day, - what is the crop, - what is the acreage. Lat/long of the site, Number of sunny days/year, what is the DG capacity (for economics), number of hours of grid availability etc.[/color]

Have a nice day

Regards

Hello,

All I am doing here by replying to your posts is to get a clarity on your document which somehow seem to portray DC solar pumping a better option than AC solar water pumping, which in my experience and knowledge is just a myth. My intention is not to “war” and its never my business. Being a technical guy your post has kindled my interest to get to know the root of the things, which unfortunately seems to be not appreciated.

If i didnt have patience or maturity or sanity like how you have put it, it would not be a second before i ignore your post and start blogging useful stuff online here.It would have been better if you arent treating me as a competitor but rather treat like a customer, infact a business customer.

Regarding the enquiry, I am not recommending your DC solution to my potential customer as I myself still not convinced and lot of questions still remains a puzzle.Just for the case, when my customer asks me what would the brand of the DC pump, I dont wish to say its “THE PEOPLE”.

Nevertheless, things apart, I honestly thank you for exhibiting lot of patience and taking time to reply my posts, but unfortunately this seems to be a never ending discussion.

Anyways wish you the best here!

Regards

Dear Mr. Saravana Kumar,

Thank you for your posts and much appreciated.

The study is intended to bring out the salient features of BLDC submersible pumps under certain boundary conditions and its advantages its offers over three phase AC motors. It is not a blanket statement. The study is not our sales pitch.   

I feel saddened to see your response on the probable DC pumping solution for your prospective client. I had asked for details which you have not shared and come to conclusion. Its unfair.

Our brand is solar gold. OEMs who offer BLDC pumping solutions are listed in the MNRE website.

Feel free to correspond.

Regards,
AgricultureInformation_part2.pdf (92.8 KB)