# power needs for well pump



## pcdreams (Sep 13, 2003)

well I've been looking at dc powered well pumps and came across this

http://store.solar-electric.com/solsdsubdcpu1.html

and here is the spec sheet

http://www.sunpumps.com/UploadDocs/Specs/SDS-D-1280.pdf

I'm horrible at electric math (mostly because I don't understand the difference in watts,volts, amps). So can someone tell me what size solar panel(s) I would need to operate this pump? (assume worse case at max depth of 225 ft.)


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## 12vman (Feb 17, 2004)

Check this out.. 


http://www.angelfire.com/pa/baconbacon/page2.html


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## pcdreams (Sep 13, 2003)

Thanks, but what I'm really having touble with is determining which panel I need

for instance (ec115) http://www.solardepot.com/pdf/EG_EC-100_120.pdf

here is a panel that has more than enough watts and amps but the volts seem to be in the mid range of the specs for the pump. Would this create an issue (efficiency)? or would this panel do the job?


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## Fire-Man (Apr 30, 2005)

pcdreams said:


> Thanks, but what I'm really having touble with is determining which panel I need
> 
> for instance (ec115) http://www.solardepot.com/pdf/EG_EC-100_120.pdf
> 
> here is a panel that has more than enough watts and amps but the volts seem to be in the mid range of the specs for the pump. Would this create an issue (efficiency)? or would this panel do the job?


PCdreams Are you going to run this pump 24/7 or will it be on a pressure switch and cycle on and off as you use water? Are you going to use batteries? Here is something to think about and to figure with---Lets do some quess-to-ments-----If the pump requires 100watts(app) per hour to operate and you are using some batteries---Then if you only run it one hour per day---it would use about 100 watts per day, 2 hrs--200 watts, 24 hrs--2400 watts, ETC. If you only planned to use it 1 hr per day, then you could get by with less than a 50 watt panel, because a 50 watt panel would give you 300+ watts per day if the sun is shining(50 watts X 6 hrs of sun=300 watts plus wattage collected for the early morning/evening hrs)--------Now if you hook 2 panels and 2, 12 volt batteries in series you will double the voltage(24+) and reduce the amps. Hope this helps!! Randy


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## pcdreams (Sep 13, 2003)

I plan to have a 100 gallon or so holding tank with some type of float that will turn the pump on when it gets to a certain level and shut off after it fills. It's suppose to pump 2 gpm so it would take roughly an hour to fill. 

Plan to have a bank of batteries (house will be solar as well.. though that may take some time $$)

you got me about the amps though (I understand the series part..sort of). but wouldnt more amps be better?

Right now My biggest concern is just getting the water out of the ground and to where its usable.


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## Fire-Man (Apr 30, 2005)

pcdreams said:


> I plan to have a 100 gallon or so holding tank with some type of float that will turn the pump on when it gets to a certain level and shut off after it fills. It's suppose to pump 2 gpm so it would take roughly an hour to fill.
> 
> Plan to have a bank of batteries (house will be solar as well.. though that may take some time $$)
> 
> ...


Sorry------I was saying if you go to 24 volts------The Pump Will Draw Less Amps(thats Good). Sure more amps/watts out of the solar panels is Good. Figure out about How many gallons you feel you will use in a day or how much time the pump will run---Then figure how big of a solar panel/'s you will need. If you get 2 50 watt panels or a 100 watt panel and a few batteries----you will be OK--with 1 to 2 hour of pumping per day---unless it gets cloudly for several days in a row. I feel that $200---45 watt solar set-up from Harbor Freight would take care of you, But If I was going to Build a system for my House too----I would get some "good" panels---that I could keep picking up a couple ever so often. Good Luck!! Randy


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## pcdreams (Sep 13, 2003)

What is concerning me is say I go with a 24v battery setup.. The pump needs 30v at depth so would I require some type of booster to get the extra 6v? or am I missing something 

I told ya I was stupid about this stuff


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## Fire-Man (Apr 30, 2005)

pcdreams said:


> What is concerning me is say I go with a 24v battery setup.. The pump needs 30v at depth so would I require some type of booster to get the extra 6v? or am I missing something
> 
> I told ya I was stupid about this stuff


The pump can run on 12 volts----up to 30 volts max. If you were to set-up on 24 volts---I am sure the pump will run fine, but if you want the 30 volts----You can set-up for 36 volts(3 12 volt panels and 36 volts of batteries--3 12volt or 6-6 volt etc.)--then on the same spec page for the pump, you can order the 30 volt controller which could be hooked to the 36 volt set-up and it will lower the voltage to 30 volts. I would try the 24 volt set-up first--then if you wanted to go to 30 volts you would have to add 1 12 volt panel and 12 more volts of batteries and buy the controller. Hope this Helps!! Randy


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## pcdreams (Sep 13, 2003)

ok that makes a bit more sense. I was thinking it would require the full 30v to pump to that depth. I'm guessing it will just run a bit slower (pump fewer gpm) at a lower voltage?

I'm all about saving money so If I don't have to buy that controler($400) I'm happy.


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## crafty2002 (Aug 23, 2006)

I'll give it a try PCDreams. The way my science teacher taught us was electricity can be compares to water in a pipe. 
Volts is like the flow rate of the water.
Amps is like how much pressure the pipe is holding. and watts is the mixture of the two above. The more pressure you have, which is the amps, and the more and the more flow you have which it the volts, the more watts you have. :shrug: It worked for me, but many in the class still never got it.

Any way. Watts is calculated by multiplying amps times volts. 
Volts are determined by devideing the watts buy the amps.

The largest pump they offer draws 180 watts and pumps 2.3 gallons per minute @ 230 feet deep. With that being the worst case senario, you could get, (I can't find my calculator so check my numbers on this)
2.3 GPM x 60 min. = 138 gallons per hour. 
A single 45 watt solar panel will put this amount of juice out in about 4 hours of sunlight. 
So on a good sunny day with a stationary panel, you should get about 200 gallons of water. 
The biggest thing I see in the way is needing a larger wire running to the pump 230 + feet long, to keep the voltage drop down for a 12 volt system.. 
The higher the volts are, the smaller the wire would need to be, and copper wire has went through the roof for some reason. 3 years ago I was buying it for $19.80 for a 250 foot roll of 12/2 w grn. It is over 90 bucks now. 
Someone chime in here if I am wrong, because I know about electricity, but as far as solar panels go, just what I have read. 
I would think, concidering the price of wire now, you would be better off buying two 45 watt panels, and setting them as fire man said, on a 24 volt system and being able to save money on the cost of the smaller wire which will help offset the cost of the 2nd panel.

I have seen some compressors that were designed to run on 120/240 volts. On 120 volts, if the pressor was set to kick back on at 50 or 60 lbs., it couldn't start. Put it on 240 volts and they ran like a charm.

Distance means a whole lot with electricity, and the longer the wire is, the higher you want to try and get the volts to it. Wire eats volts, just like water pipe eats water flow because of friction. One a 120 volt system you loose about 2 % of the voltage per 100 feet. I am not sure what the loss is for 12 and 24 volts, but I do know, it is a lot more for 12 volts than 24 volts. It is probably more like 5% and that is a lot of electricty to loose on the wire. 

The pump you have chossen will run on anything between 12 and 30 volts. It doesn't mean you must have 30 volts, but the closer you get to it the better off you are. 

Another thing I think you will find true is you will be useing the most water when the sun isn't shing so the battery bank will be holding the power except the 100 gallon holding tank. 

I would suggest two 45 watt panels. Each connected to two 12 volt batteries in series and then coming off them with 24 volts going to the pump. 
You need to check with the manufactor for the wire size required for each voltage, but I think you will find that you will save nearly enough with a 24 volt system, on the wire size aloan, to pay for the second panel. If the pump is 230 feet deep and then you have to get to the switch, you are talking about 300 feet of wire. 
I have no earthly idea why a 12 volt system is called 12 volts. When it is working perfect, it is actually 13.8 volts. :shrug: 

So "IF" I am right on my assumption of 5% voltage drop for DC systems, the 24 volts, which is truely 27.6 volts will be about 23 volts by the time it gets to the pump motor. 
The other good thing about the 24 volt system is when the batteries start to run down, on this pump, it will still run it with out any side effects.

Hope this helped you out. But I would still call the company. I'm sure they have a toll free number, and talk to one of thier salesman, not a computor or a recording, and ask about the things I brought up. I am sure they can go from there and get you on the right track. They will know what size wire etc. and lead you from there.
Good Luck
Dennis


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