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solar panel project( power is missing)

sydcal2011

Apr 23, 2012
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Hello guys:
I have:
1) 20watt solar panel, maximum voltage: 17.4V, maximum current: 1.15A

2)step down voltage regulator: input 13~40V, 12V constant output(i used a DC power supply to verify that this module always give me stable 12.27V output when input voltage vary from 13~40V)

3)12V 0.95A water pump.

I connect the solar panel to a voltage regulator and to power the water pump.

Before i make a close loop by connecting my load, water pump, with the regulator, i test the input pin of the regulator, it's something like 20.45V. Question 1, why do i get more voltage than what the spec sheet said about the maximum voltage? i am supposed to get 17.4V, according to the spec sheet, but i now get 20.45V.

After i connected the load, the input voltage on the input side of the regulator drop from 20.45V to 5V, and the current flow to the water pump is 0.8A, (which is measured by a ammeter connect the water pump in series), that makes up a total of 4W power.

Question 2, This is a 20watt solar panel, i am supposed to get around 20watt, now, i only have 4Watt power. do you guys know why the energy is missing?

Thank you in advance for your help.

Jian
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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Maybe i missed it but I don't see a model number?

Chris
 

davenn

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What model number are you talking about? I dont have that either.

model/type of solar panel

model/type of regulator

model/type of waterpump

with all the voltage and current ratings for each :)


Dave
 

BobK

Jan 5, 2010
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I have to ask: is the solar panel in full sun and in the plane perpendicular to the direction of the sun?


Bob
 

sydcal2011

Apr 23, 2012
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model/type of solar panel

model/type of regulator

model/type of waterpump

with all the voltage and current ratings for each :)


Dave

Dave, I don't think that model number matter. They are all OEM item, I get from eBay. If you do think so, please correct me. Solar panel is monosalline, regulator is step down; water pump is just a water pump, no self-prime one.
 

sydcal2011

Apr 23, 2012
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I have to ask: is the solar panel in full sun and in the plane perpendicular to the direction of the sun?


Bob

I didn't know if the solar panel perpendicular to the sun when I did the test, I just put the solar panel to somewhere that has sunshine. But I measure the output of the solar panel, it had more than 20v output.
 

CDRIVE

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Dave, I don't think that model number matter. They are all OEM item, I get from eBay. If you do think so, please correct me. Solar panel is monosalline, regulator is step down; water pump is just a water pump, no self-prime one.

More than happy to correct you..

There are more, but here's one very basic rule when posting questions on any type of help forum.

When a responder asks a question, never reply with what you think is relevant or not relevant. It's not for you to decide. If you knew what's relevant or not you wouldn't be here.

Chris
 

BobK

Jan 5, 2010
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I didn't know if the solar panel perpendicular to the sun when I did the test, I just put the solar panel to somewhere that has sunshine. But I measure the output of the solar panel, it had more than 20v output.
The open circuit voltage of a solar panel can be very different that the voltage under a load. And, in terms of the power output, being perpendicular to the drection of the sun is important. That is why efficient solar installations track the sun to keep it that way.

bob
 

sydcal2011

Apr 23, 2012
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More than happy to correct you..

There are more, but here's one very basic rule when posting questions on any type of help forum.

When a responder asks a question, never reply with what you think is relevant or not relevant. It's not for you to decide. If you knew what's relevant or not you wouldn't be here.

Chris

Chris:
My bad, i don't know any thing about model number, it is OEM item. You can easily find those parts in eBay.
Would you please tell me what model number matter?
Thank you
 

BobK

Jan 5, 2010
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How about posting a link to the panel you bought from Ebay?

Bob
 

CDRIVE

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I was particularly interested in the regulator. I wanted to see if its maximums were exceeded when you were testing it. Have you tested the Vreg again using your power supply to insure it didn't fail since the last time you tested it. You should test it with and without load.

By the way, be very cautious when dealing with maximum ratings. Some manufacturers leave no smoke margin at all because they're pushing their product. In your case the manufacturer's input max is 40V. I would not have approached this voltage. If I thought my input would ever be 40V I would have looked for something that could handle 50V.

Chris
 

davenn

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Dave, I don't think that model number matter. They are all OEM item, I get from eBay. If you do think so, please correct me. Solar panel is monosalline, regulator is step down; water pump is just a water pump, no self-prime one.

because it gives us information on the specific parts you are using.
it gives us the chance to check them out and find out their ratings etc
else we are all flying in the dark ;)

thanks for posting the links to your parts ....its what we all needed to be able to help you


Dave
 
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