100 watt solar panels

Dcmike

i have six 100 watt solar panels, 2 from renogy 2 from Missouri wind and solar and 2 from windy nation. i have a 24 volt system so i hook each set into pairs. my problem is the windy nation panels seem to be ok when i measure voc and the isc when not hooked up to any thing. but when i hooked them up to my system my tracer software only reads their out put around 1.19 amps but the renogy and Missouri ones all read over 5 amps. anyone have and idea as why they dont work while hooked up?

littleharbor2

Sounds like one of the panels has a problem. Can you hook each one of them up in series with one of the other panels? This should allow you to weed out the bad panel. If you can determine which is the bad panel you ought to try to get it replaced under warranty.

Dcmike

it just the windy nation ones i tested the voc and isc and when not hooked up they seem ok but just soon as i hook them up they dont produce much power. got me a little confused cus the other pairs work just fine 

littleharbor2

Isc. and Voc. is not under any kind of load. Can you get a automotive brake light bulb or some other 12 volt load and test each panel individually?

Estragon

Maybe the windy nation panels are a bit lower vmp than the others?

Dcmike

both renogy and windy nation  panels vmp are like 17.6 range not sure on the missouri ones but the put out the amps i think they should. just so most understand if i mix one of the windy nation panels with another panel it kills the amp out put too when hooked up to charge controller . and on another note i looked at the diode and measured them they looked and measured the same 

BB.

You need loads to draw maximum current from the array.

Either the battery bank needs to be under ~85% state of charge, or your load needs to be greater than Imp of the array. Or a combination of the two.

If the charge controller does not think the batteries need the full current (not in bulk stage but in absorb stage).

Basically, the charger needs to be in bulk mode and see around 13.6 volts or less at the battery so that it allows full current from the array.

- Bill

Dcmike

bb i understood that . that why i tested the 3 sets of panels with in a minutes of each other so there wouldn't be that big of a difference in readings, when i tested the renogy/missouri panels they all were 5,5 amps or better and the windy nation ones read only 1.09 amps

Estragon

So you unhooked 2 of the 3 pairs in sequence to do the test, with a single pair connected to the controller?

If so, my guess is a faulty connection somewhere.

mcgivor

Sounds like bad diodes bypassing strings of cells within the panel,  if everything else looks good, try removing the diodes for a temporary test, HINT, take a picture to record the orientation, without the diodes in place, full output would be revealed, at least then you would know if in fact the cells are good, diodes are cheap to replace.

mike_s

Dcmike said:

bb i understood that . that why i tested the 3 sets of panels with in a minute of each other

If you get reasonable Isc, I don't see how it can be a connection or blocking diode problem unless it's intermittent - since that proves the connections can carry full current. Same with Voc and bypass diodes - a shorted diode would reduce Voc, and an open one would have no effect unless the panel were shaded.

You said "Tracer." MPPT, right? I don't know the gory details on the algorithm it uses, but you may have to leave each set hooked up longer than "within a minute" to let it do a full sweep. Perhaps it did a sweep while the panels were disconnected, came up with a not-so-good solution, and kept that when the Windy Nation panels were connected? 

Dcmike

just today i did another test of the panels and i used a victron blue mppt charge controller (it has a pretty instant scan mode) and got same results as yesterday basically. when i hooked up the 2 windy nation panels i got 30 some volts and 1.9 amp but only 28 watts. hooked the 4 year old Missouri wind panels and bang i got 175 watts 30 some volts and 8.5 amps . im gonna look at the cells on the panels today and see if any thing is burnt and that why they dont work right . one good note windy nation is sending me one panel they for think is bad 

mike_s

Dcmike said:

when i hooked up the 2 windy nation panels i got 30 some volts and 1.9 amp but only 28 watts.

?
30 V x 1.9 A = 57 W, not 28 W.
30 V x 8.5 A = 255 W, not 175 W.

Where are those numbers coming from?

Dcmike

the victron blue software 

mcgivor

mike_s said:

If you get reasonable Isc, I don't see how it can be a connection or blocking diode problem unless it's intermittent - since that proves the connections can carry full current. Same with Voc and bypass diodes - a shorted diode would reduce Voc, and an open one would have no effect unless the panel were shaded.

Diodes generally fail short circuit but don't necessarily fail completely, there can be deterioration over time resulting in partially shorted diode, this would appear as reduced current, but not necessarily lower VOC. Temporarily removing the diodes would eliminate the possibility of a partial bypass, revealing the actual current the panel can supply, if it is still low, then possible cell damage has occurred. Always replace the diodes after testing.

mike_s

mcgivor said:

Diodes generally fail short circuit but don't necessarily fail completely, there can be deterioration over time resulting in partially shorted diode, this would appear as reduced current, but not necessarily lower VOC. 

Explain how he then gets full Isc.

mike_s

Dcmike said:

the victron blue software 

24V system, with the battery at 16.07V, and a charge state of float? Something's wrong, and it's not the panels.

mcgivor

mike_s said:

mcgivor said:

Diodes generally fail short circuit but don't necessarily fail completely, there can be deterioration over time resulting in partially shorted diode, this would appear as reduced current, but not necessarily lower VOC. 

Explain how he then gets full Isc.

Working with second hand information in a ping pong communication is difficult, especially when it seems that things don't look right, my suggestions are a means, through process of elimination, to determine what the problem is, an offer of help, which can be accepted or ignored, it's just what I would do in similar circumstances. Not being there, I can neither  confirm nor deny what the instruments used, recorded, I can however say, electronic components can mislead one into believing the instruments used are correct, when in fact they are not  40 plus years of experience has shown me that things are not always what they seem. Personally I would want to know why something doesn't work, knowledge is earned and information is not knowledge. There is no intention to insult your comment, in fact all coments are valuable, if they are positive.

Dcmike

mike_s said:

Dcmike said:

the victron blue software 

24V system, with the battery at 16.07V, and a charge state of float? Something's wrong, and it's not the panels.

i had put the panels on the victron blue mppt it a different system than the 24 volt system on the tracer mppt from my 1st post sorry about confusion 

littleharbor2

Have you isolated the bad panel yet?

Dcmike

littleharbor2 said:

Have you isolated the bad panel yet?

yes i have taken them off the system now and working with windy nation to get it right. they are sending one new panel for the one they are for sure think is bad but i pretty sure both are bad. i dont wanna mess with diodes just yet if they want panels back for warranty 

mike_s

Are you going to provide details, or just let us keep guessing?

Making the assumption that it's a 12 V system, using lead acid batteries, one wonders why it's floating at 16 V. Anyway, since it's floating not charging, it only takes minimal current to hold the voltage so it's not a valid indication of what the panels are capable of. As has been mentioned multiple times, you need to put a load on it if you want to see what the panels can do.

Dcmike

well the details on the my 1st post on the 24 volt system is 2 agm 155ah battery's now the victon blue mppt is on a lithium battery pack that i did not wanna say about because it erks to many when you mention lithium battery's . 

littleharbor2

Did you try to put a load on both of those panels? That would easily weed out any problems.

Dcmike

littleharbor2 said:

Did you try to put a load on both of those panels? That would easily weed out any problems.

thats how figured they were bad, when just checking they seem fine, but soon as i hook them up to any charge controller i have they just wont put out the amps they should

littleharbor2

So you hooked up one at a time?

Dcmike

littleharbor2 said:

So you hooked up one at a time?

yes i even have a 12 volt system not mentioned and have tried them one at a time on that system with out any good results 

littleharbor2

OK, good to know.  I now wonder if Windy nation has a problem run of panels. Two bad panels is unlikely unless a problem batch or there was some catastrophic event took them out.

Dcmike

well with 100 watts panels getting so cheap and most made in china, i wouldn't doubt they have a bad run of them every now and then

littleharbor2

12 volt panels are still relatively expensive. I have 285 watt 24 volt panels for $100.00 and can hardly sell them now that the price of larger panels have dropped so low.

Dcmike

i so wanted to get 24 volt panels but the dang truck shipping is to much. so i just stick with 100 watt panels