Solar Panel repair

[KirstinS]

Morning

I have one of these which is faulty and the sunhine this weekend finally gave me an opportunity to diangose issue

http://www.amazon.com/Sunlinq-Portable-Solar-Panel-Charger/dp/B001TI6SP8/ref=cm_cr_pr_pb_t

It has 8 panels and is 12v and 12w. There is a 4 panel version which is 12v 6.5w

This leads me to conclude that each solar cell is 3v nominal and my 8 panel version is 4s 2p. Does this sound right ?

The fault is due to corroded wiring between the panels - (it got soaked with seawater by accident)

Yesterday I managed to get one bank of 12v working. (only read 11v actually but it was nearly 5pm)

Without a watt meter (I just have a multi meter) I’m not sure I can be sure that both sets of 4 cells are working correctly. If just one bank is working the multimeter will read 12v

If both are working it will read 12 volts too.

way to be sure both are ok without a wattmeter ?

 

[jhruk]

Just connect your voltmeter and cover over each bank of panels in turn. The voltage will drop to zero if you cover the only working bank. If it doesn't drop they're both working.

 

[KirstinS]

hi jhruk

Thanks - not sure I explained myself very well. I undertand what you are saying - yes I can test each bank individually and esnure each is working. However , when I test the output overall I cannot be sure that both panels are feeding into it just be seeing 12v.

The wiring has had many faults and is very hard to get at sandwiched between plastic and a ripstop type fabric..

So yes I can test the banks to see they work individally but is there a way to test the combined output is 12v 12w (both panels) and not 12v 6w (one panel)?

I do have an old IMAX b6 charger for lipos. I thought that maybe by hooking this up to the panel and seeing what amps the setup can give without going into error this may give some indication

if 12w then efeectivly its a 2a charger. If the IMAX is ok to charge a 11.1v lipo pack at 1.5a then it must be running on both banks. If it fails then just one

does this test make sense ? I think it does

 

[neptune]

To get a rough idea of the output, use your multimeter. Connect the solar panels to a battery. Then disconnect the positive lead from the battery. Set meter to measure amps. Connect positive lead of meter to panel positive. Connect meter negative to battery positive. Assume the voltage as 12 volts. Watts = Amps times volts. Do the test in bright sunlight. Warning . do not connect the meter when set to "Amps" directly across battery or panel, or it will blow the meter fuse if it has one, or fry the meter.

 

[jhruk]

Hi KirstinS,

You seem to be concerned that only half your 8 cell panel is working. If the cells are wired 4s2p, as you claim, and you have tested that each 4s bank is working, by the method I described above of covering each bank in turn while monitoring the combined output voltage, then surely the whole panel must be working.

Am I missing something?

 

[KirstinS]

Hi KirstinS,

You seem to be concerned that only half your 8 cell panel is working. If the cells are wired 4s2p, as you claim, and you have tested that each 4s bank is working, by the method I described above of covering each bank in turn while monitoring the combined output voltage, then surely the whole panel must be working.

Am I missing something?

Ahh, finally the penny has dropped for me. No , you are missing nothing - it was me. The easy and obvious solution is just as you suggest

I was totally over complicating this!

Thanks

 

[KirstinS]

To get a rough idea of the output, use your multimeter. Connect the solar panels to a battery. Then disconnect the positive lead from the battery. Set meter to measure amps. Connect positive lead of meter to panel positive. Connect meter negative to battery positive. Assume the voltage as 12 volts. Watts = Amps times volts. Do the test in bright sunlight. Warning . do not connect the meter when set to "Amps" directly across battery or panel, or it will blow the meter fuse if it has one, or fry the meter.

Thanks this is very helpful test of actual output once I get it working

 

[Scimitar]

You'll find the maker's claim is wildly optimistic, of course.
Having said that, I had great success with a fixed (ie, not flexible) but portable panel set up in the windscreen of a car I'd just put off the road after I'd bought a new (expensive) diesel battery for it.
It sat for four years, only being trickle-charged by this 15W panel all year round and went back into service still pretty fresh. It lasted another couple of years in normal use until a savage cold night killed it.
Hooking the panel up to an ammeter on different days revealed that on full sun, it was charging at 350mA, dull autumn days, 250mA, and miserable wet, cold winter days, 150mA. Some days it dropped to as little as 60mA, but there was always something.
Being a 15W panel was a total lie, of course - it was really a 5W panel for the UK/Irish conditions. 15W might have been attainable in the tropics.