current from 36 cells monocrstaline

[Algie]

i just made a 6 X 6 monocrstalline panel and current being read from this panel is just maximum at noon 2.1 A obvoisly with a load connected ( 12 V battery ) these monocrstalline cells should give 4 A each so at least i should get 4A from the total 36 cells connected in series voltage is good 13.5 loaded with same battery.

Is it me thats seeing it strange or is it normal to have around 2 A

[snake21]

try to disconnect the panel from the battery and test for amps.you will get the max amp at that open voltage.then you calculate power  and divide by the voltage of the battery.i think it should round up to the amps you may get if connected to a 12v battery

someone plz confirm

[Algie]

thanks mate for your reply

if i disconnect from battery how can test the Amperage?  its an open circuit

this is the panel im talking about

[mab]

Measure open-circuit for voltage and short-circuit for current.

I would expect the best part of 4-5A short circuit and ~20-25v open circuit.

make sure it's full sunlight, not a very hazy day.

Oh, and make sure you meter's reading right - there's nothing that'll waste more time when fault-finding than a dodgy meter. (been there - done that)

[dave ames]

 Hey Algie,

Ain't this stuff a blast?  yep, we are definitely interested in the short circuit current (ISC) we will find that the loaded current in full sun is not much under the ISC (about 10% less).

couple things after that...we want a good load on the battery when checking our loaded performance.(could be it's somewhat charged and only accepting a portion of whats offered up by the pv)

also, we want to make sure we weed out any "dogs" before the assembly. gotta check each cell in full sun. (this bit is a pain but much needed step..one bad apple drags the whole array down!)

we can't skimp on the tabbing..(looks like you may be only partially tabbing those cells..we need to tab all the pads top and bottom)

...and welcome to the group.
 best regards, dave

[oztules]

If they are 6x6 you should expect near 8A short circuit in full sunlight...... should be 4W cells (8A x .5V)

What Dave said about the tabs is important.... front and back. You will lose current otherwise.

Look forward to seeing your final panels.



.............oztules

[Algie]

Thanks for your feedback mates

I forgot to tell you that the cell is facing directly the Sun no eva and no glass, cell and sun direct to each other.

reason is i still found nothing compared to IRON FREE SOLAR GLASS

will post meter results tonight waiting for the sun to charge up

[Algie]

Well here are the results of the day panel in sun and amp meter connected;

this pic was taken at 1000 you can notice the angle of the panel

meter reading were 18.5 V and 6.83 A so power was 126 W

[Algie]

This reading was taken at 1230 maximum sunlight;

meter readings were:

18.2V 7.52A so power was 136.8W

[TomW]

I gotta say I love your high tech positioning jig!

I am no expert on glass, solar or anything much but...

Don't get too hung up over the glazing.

If it costs a lot to make a "perfect" unit and a cheap, available option will give you most of the benefits of some high end material does it make sense to spend a large portion of the project budget on the perfect glazing? Perhaps you could build a bigger panel or more panels to offset the losses of "good enough" glazing? It depends on the numbers but I suspect the loss thru iron bearing glass is not a large percent. I don't know for sure.

That is the question I would be pondering.

Sometimes, good enough is, well, good enough.

Just another angle to consider.

Good luck with the RE desease. It has no cure and we tend to be enablers here!

Tom

[DamonHD]

Have to agree with TomW: keep it simple and most likely get better value for your time and equipment overall.

Mind you, he has a tracking solar array which I consider to be overthinking the plumbing!  B^>

Rgds

Damon

PS. I also like your hi-tech support structures.  Maybe you should sell them to NASA or an art gallery under some title such as "Sun essence and the art of recycling...": my cut is 1% as your agent.  B^>

[Algie]

thanks for your comments on the "high tech Jig"

well thats just the base of the solar panel aluminium base EVA and solar cells, frame and facade will come as soon as i find right glass to it will post a pic of the panel when ready :-)
aiming of making 2 of these panels on a polar mount to make them rotate with the sun as well

regs

[oztules]

I'm confident that if you were to use decent wires to your meter, and used full tabbing, you would easily get your expected 8amps.

6.7A with those leads and what looks to be single tab connection is very good. (use short bits of heavy wire from panel into the meter sockets to check this quickly if you wish)

If you get rid of all resistance points (thin wire,  single tab wire connections etc), you will do very well. Window glass will only degrade the expected behind glass result by about 10 percent..... much less than poor leads contribute.

Tomw is right. In this case, window glass will do fine as far as results are concerned. Hail damage is another matter, and can only be addressed on a regional basis perhaps.

Iron free glass versus normal glass is only a 5-10% type of problem.... only relevant if you have competitors. If you can source thin toughened glass it would be a good substitute.... otherwise window glass will work fine. just a touch more fragile. Thickness also counts. Thicker= more loss.... thinner is better loss wise, but more fragile... just another compromise for you to ponder.

Looks like success is close.





......................oztules