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checking a solar panel.

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Posted by fabtraninbox on November 1, 2008, 6:00 pm
i brought a solar panel from my friend. it is manufactured in 1993it
is 4 x 1.5 feet in size with 36 cells.i am not sure about the  watts.
it is written 64 series probably i think it may be 64
 watt.but when i checked in sunshine with out any load it is giving
19 volts, but when i check for amps i am getting only 0.2 amps. does
this panel work to charge a battery.


Posted by Eeyore on November 2, 2008, 12:54 am

fabtraninbox@gmail.com wrote:

Short circuit amps ?

19 volts in full sunshine is fairly typical-ish.

Are the cells circular ? Measure their diameter and that will give the
effective panel size. And where do you live ? Insolation (the amount of
sun) varies with location. From all of this one might be able to tell if
your panel has aged.

If you connect it to a battery directly the voltage will drop due to
loading. Unless it has inherent reverse diode characteritics the battery
may lose power into the cells when it's dark.

Charging a battery this way is not clever. It's primitive and may not do
that battery any good. You really need a proper charge controller and
preferably a 'maximum power point' type.


Posted by fabtraninbox on November 2, 2008, 3:28 am

Short circuit amps is 0.2
the cells are circular and 4 inches dia.
i live in india ( visakhapatnam) we have a goodshine with min day temp
22 to max day temp 45 deg.
basically i want to know if this solar panel is in working condition,
later i will proceed for next step (charging)
i came to know  that 14 volts is required to charge a battery.
 what is the  minimum amps required.
thanks for your valuable response

Posted by PhattyMo on November 2, 2008, 7:40 am
 0.2A (200ma) seems awful low for a panel that size.
200ma and an assumed 14V,is 2.8Watts. Not much at all.

fabtraninbox@gmail.com wrote:

Posted by Eeyore on November 2, 2008, 10:29 am

PhattyMo wrote:

I fear so. But better than nothing.

Interesting data though. Maybe lifetime is currently being over-estimated or
these were originally relatively low efficiency panels.


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