Solar Water Pump for Irrigation

What is the flowrate?

For a good photovoltaic cell, 6X4 inch that gives 2.5A & 0.5V under Houston sky, at noon in July, I made some very elementary calculations.

For the 25HP that you need for your pumps, you will need, roughly, 2500 sq ft of such cells.

Add the inverters, batteries for such charge.

I recall that they estimated $8,000 to $10,000 per installed KW of photovoltaic power. The best life time I have seen, was 15 years.

I think that solar electrical power is still very expensive.

What about DC pumps I would not need the inverters where I want to install them its one of the hottest places on earth and it receives immense sunshine.

I am a believer in photovoltaic power, and I am sad to see the ant steps toward increasing the output of the cells and, in the same time, decrease the price.

If you use dc pumps (I do know nothing about this) you have not the inverter trouble. Also, if pumps are used only when there is sun, you do not need batteries.

Still, 25HP means 18.6KW and, in order to have this power, you will need about 2,500square foot of cells.

But if there is not any electric source around, it might be cheaper to build this photoelectric plant than bringing electricity over there. It is an economic study for which you know more than me.

Here are some links. You can google photovoltaic power, too.

http://www.gepower.com/prod_serv/products/solar/en/downloads/gepvp200_datasheet_600.pdf

http://www.solarpowerconference.com/

http://www.sharponenergy.com/pdfs/SRSBrochure.pdf

After I posted, I found this "bargain":

http://www.solarhome.org/index.asp?PageAction=VIEWPROD&ProdID=2226

I would agree. The Hp required for this situation makes a solar power system a bit questionable from a cost perspective..

To replace a 24/7 system with a 8/7 system the irrigation system would have to be trebled. It may be too expensive at present.

But in SA with load shedding it may be absolutely necessary.

I think 3 to 5 hp motor is sufficient to fetch water from Bore.

Why 25 hp motor is reqd?

Hello Combined,

You may have an interest in a home built solar pump that has been upgraded to an electric generator driven by a francis hydro turbine.

As you may be aware active gasses up to and including Hydrogen are extremely expansive when subjected to heat (see heat pumps) and any of those gasses can be used to operate a possitive action water pump which literally has no moving part except a floating ball and one way valves.

The remainder is water pipe only if water does not need to raised to the intake, and a venturi if water needs be raised from a depth below the pump intake. (up to 200 ft)

Construction is simple cut and weld, with a hole drilled at one point.

The Solar heated gas after being exploited is recooled by the water.

Due to commercial interests the exact working cannot be made public at the moment however they can be supplied in confidence if you so wish for personal use.

Cheers

Peter

dasenergy@bigpond.com.au

You did not mention how long your 25HP pump operates on any given day nor did you specify the flow rate. There is not enough info here to even suggest a system.

First you need to clarify exactly how much water per day you need- NOT the hp of the pump or the pipe diameter. I can show you a 200W pump that can pump water from a 250' well (albeit slowly).

Second, you need to specify how much water you need per day in the summer and in the winter. Summer is hot which increases evaporative losses and more water is usually required for both crops and livestock due to higher transpiration rates. On the other hand, there is usually twice as much sun in the summer than in the winter.

With a solar pumping system you spread the water pumping requirement over a much longer time frame (say 8 hours rather than one hour). This results in lower flow rates and generally more efficient water transfer- especially when using DC pumps that can operate efficiently at reduced speed. You may find that the 25hp pump that you have now is replaceable with something as small as a 3-5hp pump (or smaller) which means your PV array could be as small as 3-4KW. Or it could be huge- again there is not enough info to make an informed guess.

As for lifetimes, most PV modules currently sold have 20 or 25 year warranties that guarantee at least 80% of rated output at the end of that period. Someone will be fighting over my own (currently 12 year old) PV array long after I am dead (hopefully in another 100 years or so) because it will still have significant output (probably 50-60% max rated).

Pump lifetime is unknown but since solar pumps operate much more slowly they have considerably less wear that a high speed AC equivalent. Also DC motors tend to last longer because they are generally built better (main reason they are more expensive). DC motors are also more efficient, generally 20-40% more efficient than a typical AC pump.

Tracking systems make a lot of sense if you are in the middle of flat land. Trackers can increase real PV output by as much as 30% per day (meaning 30% fewer PV modules required).

Cost effectiveness will be determined by what your rate for electricity is and what sort of government (local, state and fed) incentives or tax breaks are available in your area. The cost of solar PV should see a significant drop in the first half of 2009 since that is when the new silicon processing plants will be coming online. The current high price for PV is mainly due to a shortage of high grade silicon worldwide- the demand has been so high that prices for PV have not dropped even though there have been huge improvements in economy of scale. Once the cost of silicon comes down the cost for PV will drop as well.

Hope this helps!

Now, this is a good answer, and I don't like the GA point to go to an anonymous person. If you would like to share more about your system I would be happy to read. Like installed power; the sun situation over your house; is it made by you out of individual cells, or by assembled panels; cost; what maintenance is it required; have you met a hail situation?

I didn't find answers to many of these questions and, probably, many would be interested, too.

Regarding Dc solar pumps all those I have found on internet are of low capacity i.e. the flow rate is quite low what is the maximum wattage DC solar pump available currently and do DC pumps also have the same starting current drain problem while starting like the AC pumps.

www.sierrasolar.com/index.php

Scan through, Home Power Magazine. www.homepower.com. Articles, designs and suppliers.

Good luck,

James