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11-14-2018, 12:41 PM
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#41
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,685
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Quote:
Originally Posted by DLDINS
Hello all,
I am an electrical engineer with experience in solar technology. I could pontificate for a long time, but for this point of this thread (which initially asked about diodes) I would just like to mention that you can add a "ideal diode" circuit instead of a actual diode. It consists of a controller IC and power MOSFETs that then simulate the function of a diode. Since the FET has a very low "on resistance" you get the function of a diode with only 20mV to 50mV of forward voltage loss.
One such control IC is the LTC4359:
https://www.analog.com/media/en/tech...ts/ltc4359.pdf
There are families of this with different features, but I am just letting you know they exist.
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Hi
..... but Linear is now par of the AD evil empire ....
Bob
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11-14-2018, 02:11 PM
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#42
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Wolfwhistle
Margaritaville
, Banana Republic
Join Date: Jul 2018
Posts: 705
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It is my understanding that you can use watt mismatched panels if cell count is the same (voltage very close) for parallel arrangements or... current matching panels where the cell count is different when connected in series. Having only experience with Renogy and I am sure all with diodes , a shaded panel does not affect the rest in full sun. My only experience thus far is with Bogart / Trimetric and only parallel to this point. MPPT and series one day, but if is not broke I’m leaving it alone. Same with batteries FLA or AGM has been all I need.
WW
__________________
Is taking it all with you, really getting away from it all?
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11-14-2018, 03:31 PM
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#43
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,685
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Quote:
Originally Posted by Wolfwhistle
It is my understanding that you can use watt mismatched panels if cell count is the same (voltage very close) for parallel arrangements or... current matching panels where the cell count is different when connected in series. Having only experience with Renogy and I am sure all with diodes , a shaded panel does not affect the rest in full sun. My only experience thus far is with Bogart / Trimetric and only parallel to this point. MPPT and series one day, but if is not broke I’m leaving it alone. Same with batteries FLA or AGM has been all I need.
WW
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Hi
Unfortunately there are several ways to fab a basic solar cell. Yes, they all convert light to power, but the voltage vs light curves aren't the same. You really would like the curves to match up if at all possible.
If you take a look at a plant where they make panels. There is often a sorting process on the incoming cells. That's even with them all being same fab technique. They then get stacked so that each string comes out to whatever the target is. Since vendor A's target may not be vendor B's .... .even with same fab approach you get variation.
Bob
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11-15-2018, 05:56 AM
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#44
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Rivet Master
2007 30' Classic
KW
, Ontario
Join Date: May 2012
Posts: 996
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Quote:
Originally Posted by uncle_bob
If you take a look at a plant where they make panels. There is often a sorting process on the incoming cells. That's even with them all being same fab technique. They then get stacked so that each string comes out to whatever the target is. Since vendor A's target may not be vendor B's .... .even with same fab approach you get variation.
Bob
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No plant I have ever worked at or with had or has a sorting process. You purchase in the cells that have already been graded to a degree. Once the panels are built and tested they are then sorted. Even though you have a target of a certain wattage per panel they can easily vary by at least 50 watts on a large panel. That is what the grading is for. Typically 4-5 different grades. The voltage target is the same on all of the panels, but again the final results vary, but are close enough to allow you to group them. We also had our own plant making the cells and the variation is extreme. Whether crystalline or amorphous (vapour deposition) the results can and will vary. Panels are always graded at the end. It would take forever to grade the cells when making the panel, which is impossible in a production environment. The stringers are slow enough as it is and multiples of them are needed just to keep up the production.
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11-16-2018, 07:07 AM
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#45
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,685
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Quote:
Originally Posted by gator.bigfoot
No plant I have ever worked at or with had or has a sorting process. You purchase in the cells that have already been graded to a degree. Once the panels are built and tested they are then sorted. Even though you have a target of a certain wattage per panel they can easily vary by at least 50 watts on a large panel. That is what the grading is for. Typically 4-5 different grades. The voltage target is the same on all of the panels, but again the final results vary, but are close enough to allow you to group them. We also had our own plant making the cells and the variation is extreme. Whether crystalline or amorphous (vapour deposition) the results can and will vary. Panels are always graded at the end. It would take forever to grade the cells when making the panel, which is impossible in a production environment. The stringers are slow enough as it is and multiples of them are needed just to keep up the production.
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Hi
You automate the process so it goes quite quickly. The same "flash it and measure" (or some variant) gives you the data. A computer does the math. A very normal pick and place does the handling. The sort may simply allocates the cells between the strings. You don't see everybody out there selling 85,90,95, and 100W panels all in the exact same size ....If they just "do that" (without any labeling) and you drop in a 100W next to a 85W things are not going to be ideal ....
Bob
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11-16-2018, 09:29 AM
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#46
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Rivet Master
2007 30' Classic
KW
, Ontario
Join Date: May 2012
Posts: 996
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Quote:
Originally Posted by uncle_bob
Hi
You automate the process so it goes quite quickly. The same "flash it and measure" (or some variant) gives you the data. A computer does the math. A very normal pick and place does the handling. The sort may simply allocates the cells between the strings. You don't see everybody out there selling 85,90,95, and 100W panels all in the exact same size ....If they just "do that" (without any labeling) and you drop in a 100W next to a 85W things are not going to be ideal ....
Bob
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You obviously have no idea of what you're talking about do you? Have you ever worked in a solar factory? Have you ever been inside one? I've been in them around the world. Working for the largest producers in the world. This was my specialty for years.
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11-16-2018, 11:49 AM
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#47
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4 Rivet Member
2017 27' International
Lake Havasu City
, Arizona
Join Date: Feb 2017
Posts: 310
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I don't question your experience, gator.bigfoot, but you could be more polite about expressing your opinion.
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11-16-2018, 07:14 PM
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#48
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Rivet Master
2007 30' Classic
KW
, Ontario
Join Date: May 2012
Posts: 996
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Quote:
Originally Posted by Paprika
I don't question your experience, gator.bigfoot, but you could be more polite about expressing your opinion.
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You're right, I didn't express that politely. Rough day. My apologies Bob.
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11-17-2018, 07:45 AM
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#49
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,685
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Quote:
Originally Posted by gator.bigfoot
You're right, I didn't express that politely. Rough day. My apologies Bob.
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Hi
Well, oddly enough, I have bad days as well.
Yes, I have seen exactly the process I described being used. No I can't get into any more of the details. Sorry about that.
Bob
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11-18-2018, 07:55 AM
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#50
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Rivet Master
2007 30' Classic
KW
, Ontario
Join Date: May 2012
Posts: 996
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Typically they aim for much higher outcomes. So when they get the lower ones they can still sell them. I don't think there is that much of a demand for 100 watt panels anyway. The money is in the large panels. The grading on the higher output panels is usually classified by 10 or 20 watts so you don't have all these piles. Many of the lower grade ones you will never see come to the NA market.
Unloading is often done with something like a Dalmec. For a robot to have the reach it needs it would be too costly. Some of the panels are more than 2 meters by 2 meters in the amorphous world.
What you may see is one robot share in the unloading of a couple of grades. It's much less expensive to move the panels onto a separate conveyor once they're tested.
We have used overhead an gantry for this process as well, but again it makes things much more expensive. In one facility they used a bath tub for final testing.
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11-19-2018, 08:34 AM
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#51
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,685
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Quote:
Originally Posted by gator.bigfoot
Typically they aim for much higher outcomes. So when they get the lower ones they can still sell them. I don't think there is that much of a demand for 100 watt panels anyway. The money is in the large panels. The grading on the higher output panels is usually classified by 10 or 20 watts so you don't have all these piles. Many of the lower grade ones you will never see come to the NA market.
Unloading is often done with something like a Dalmec. For a robot to have the reach it needs it would be too costly. Some of the panels are more than 2 meters by 2 meters in the amorphous world.
What you may see is one robot share in the unloading of a couple of grades. It's much less expensive to move the panels onto a separate conveyor once they're tested.
We have used overhead an gantry for this process as well, but again it makes things much more expensive. In one facility they used a bath tub for final testing.
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Hi
Keep in mind that we are talking about the panels that people put on top of an AS. I have yet to see anybody pushing units that are much above 100W in any of these threads. This *is* a niche market.
Bob
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