Issue with solar cell tabbing/wiring into a series...PLEASE HELP!

[sultan316]

Ok so to start, this is my first DIY panel and I'm doing it the old fashioned way with treated plywood and pegboard. I know about EVA and everything, but I'm just making this for learning purposes and for fun.

After finally finishing tabbing all of my cells, I began to connect the bus wire to them and noticed that after checking with my multimeter, the voltage was being subtracted as I went from one column to the next. I soon realized that I had tabbed all of my wires the same way, possibly leaving me to make a mistake. I tabbed the positive side first (back side) and then connected that to the negative of the next cell and so on. I made 3 columns of 13. I know typically people make 12x3, but I had a good amount of extras and figured I would tack on 1 more row since I had some room (this may be mistake #1, please let me know). All 3 columns were tabbed the same way, and when it came down to adding the bus wire, I added an extra piece of tabbing wire to the negative side of the top cells on the first row in order to attach to the bus. Here is where I noticed my problem. The picture below will be able to explain my problem.

I realized the error I had made because in the transition to the next column, it was going from positive to positive I believe, so I cut the tabbing wire and attached it to the top (negative side) of the middle column on the last row. I apologize if I'm not explaining this correctly. Before I do anything drastic (because I have already glued it down to the pegboard using silicone; I know dumb move...) I want to know what my next step should be.



I was about to cut the tabbing wire (as shown in the picture) on the top middle and try and solder it to the bottom (might have to break that cell since its stuck on there), but I'm starting to think the smart solution was to completely flip that middle column around.

I dont understand why I'm making this so difficult. It's a simple series ughh... PLEASE HELP! can't proceed without you. Many thanks

[inetdog]

I realized the error I had made because in the transition to the next column, it was going from positive to positive I believe, so I cut the tabbing wire and attached it to the top (negative side) of the middle column on the last row. I apologize if I'm not explaining this correctly. Before I do anything drastic (because I have already glued it down to the pegboard using silicone; I know dumb move...) I want to know what my next step should be.


I was about to cut the tabbing wire (as shown in the picture) on the top middle and try and solder it to the bottom (might have to break that cell since its stuck on there), but I'm starting to think the smart solution was to completely flip that middle column around.

I dont understand why I'm making this so difficult. It's a simple series ughh... PLEASE HELP! can't proceed without you. Many thanks

Well, if your diagram is correct, the cell where you switched the lead is not even in the circuit anymore. Since you made three rows, each of which starts with the negative end of the row on the left and the positive on the right, you will have to run the wire from the right end of the top row to the left end of the second row, and from the right end of the second row to the left end of the third row.

To use short interconnects of the type you drew, you would have had to glue down the middle row running in the opposite direction from rows 1 and 3.

Having an odd number of cells in each row is not causing any problems.

Think of it as laying three AA cell batteries next to each other and trying to wire them in series. Either you turn the middle one around or you run the interconnects from one end of a battery to the opposite end of the neighbor battery.

[Mike90250]

I'd have to do some fancy photoshop of your sketch, to show the error, right edge, the cell with your arrow pointing to it, study how you have drawn the tab wire over the back of the cell, and not contacting the front at all...

Sketch all the cells in a single row, and then, where you would turn the corner, and route the cells back, SEE the pattern, top to lower, top to lower, top to lower. That should never change.

So anyway, this is only an experiment, and you will not be installing on a house or inhabited structure, right ?

And you will need to learn about Bypass Diodes too.

[sultan316]

Ok so what I said at first was correct, I should have flipped the middle column completely and not even worried about cutting and re-soldering. Well damn. How can I redo that after having glued down my cells? Is it possible without breaking?

And the diode is to prevent the current from going in the opposite direction. I already have a charge controller, so I shouldn't need one right? Also, yes I will be using it on my house. While it is for experiment, that doesn't mean I'm just going to throw it away after? Why would I not use it? I'm just not going to make any more most likely and only use this for small things.


Oh and lastly, thanks guys, as I understand where I overlooked. I was overcomplicating everything after reading conflicting reports. Just need to figure out how to fix it without breaking everything...

[Mike90250]

There are 2 functions for diodes in / near PV panels. Internal ones are BYPASS to help prevent damage from shading. External ones are BLOCKING and charge controllers often provide that function.

Search the web for more info about these.

http://www.solar-facts.com/panels/panel-diodes.php

[axis11]

The layout is not exactly the same as it is made of 4 columns of 9's but it should be enough as a guide.

[Mike90250]

@ axis11
Nice pics of the layout. Thanks .

[inetdog]

Ok so what I said at first was correct, I should have flipped the middle column completely and not even worried about cutting and re-soldering. Well damn. How can I redo that after having glued down my cells? Is it possible without breaking?

Oh and lastly, thanks guys, as I understand where I overlooked. I was overcomplicating everything after reading conflicting reports. Just need to figure out how to fix it without breaking everything...

I can see two possibilities:

1. Use a saw to cut apart the rows of cells still attached to the pegboard and turn the middle row around. (Not recommended!)
2. Change your wiring only. (Get ready for some totally amazing graphics!)

What you should have done:

should.have.jpg

What you can do to fix up what you have glued down:


fix.up.jpg

[sultan316]

Mike: I've actually seen that exact website before, but I put it off because I will only be having 1 panel. Do I still need a bypass diode if I only have a single panel? I figured since I'm not wiring them in series with another panel, it would be useless.

Axis: Great graphics. Everyone is confirming then my problem especially with that representation. I just need to know what the best method is to fix this. I still can't for the life of me figure out why I glued them down. I think I just wanted to make the next step happen already.

inetdog: I'm not sure I want to cut out my pegboard. The unconventional rewiring is what I was thinking at first. I'm having a little trouble making out your diagrams, but if I read it correctly, then you're suggesting to bring down tabbing wire from the top to the bottom of the middle row? If so, can you elaborate more on it, or describe your diagrams a little more. Thank you.

Do you guys think there is a way to release the silicone a little and somehow use a spatula or something to release it? I adhered it about 36 hrs ago maybe?


Thanks guys, getting some good responses here. Glad this forum is active in helping out.

[inetdog]

inetdog: I'm not sure I want to cut out my pegboard. The unconventional rewiring is what I was thinking at first. I'm having a little trouble making out your diagrams, but if I read it correctly, then you're suggesting to bring down tabbing wire from the top to the bottom of the middle row? If so, can you elaborate more on it, or describe your diagrams a little more. Thank you.

I tried describing it in an earlier post, but it did not seem to work for you. (BTW, did you click on the thumbnail to see the full size graphic?)

Connect a wire from the + (right in your diagram) end of the first row to the - (left in your diagram) end of the second row.
Then do the same from the second row to the third row. There are no short connectors between the rows at either end.

Just think about what you would do to make a series circuit if you had rows of batteries in holders instead of photocells.

[sultan316]

I tried describing it in an earlier post, but it did not seem to work for you. (BTW, did you click on the thumbnail to see the full size graphic?)

Connect a wire from the + (right in your diagram) end of the first row to the - (left in your diagram) end of the second row.
Then do the same from the second row to the third row. There are no short connectors between the rows at either end.

Just think about what you would do to make a series circuit if you had rows of batteries in holders instead of photocells.

Ohhh ok, for some reason I thought you were saying something different. I went back to your earlier post and understood it now. So just to confirm:

1. I should change back the piece that I resoldered (as shown in my drawing) from negative back to positive.

2. All of the joined bus wires should just be cut since they are of no use anymore. Instead, each row should have a single bus wire connecting the two tabs from that cell. At this point, each row should have the exact same configuration, facing the exact same way.

3. Starting from the 1st column, I should run tabbing wire all the way from the top-most cell on the right end of the bus wire, down to the bottom-most cell in the 2nd column on the left end of the bus wire.

4. Now on the top-most cell of the 2nd column, I should run tabbing wire from the right end of its bus wire, all the way down to the bottom-most cell of the 3rd column on the left end of the bus wire.

I think what I said is correct, but please correct me if I'm wrong.

I just hope I have enough tabbing wire left to do the job. If I don't, I could just attach some of the remaining bus wire to the end of the tabbing wire to make it longer right? Oh and if this is possible, I could also cut the bus wire in half if it's too thick, correct? I can't believe how ghetto/unconventionally I'm doing this right now haha.

Lastly, if I don't have enough room in between my columns to run the tabbing through, is it fine if it covers a very small portion of the cells? I'm assuming it should just minimally reduce the output, but should be fine.

[inetdog]

Ohhh ok, for some reason I thought you were saying something different. I went back to your earlier post and understood it now. So just to confirm:

1. I should change back the piece that I resoldered (as shown in my drawing) from negative back to positive.

2. All of the joined bus wires should just be cut since they are of no use anymore. Instead, each row should have a single bus wire connecting the two tabs from that cell. At this point, each row should have the exact same configuration, facing the exact same way.

3. Starting from the 1st column, I should run tabbing wire all the way from the top-most cell on the right end of the bus wire, down to the bottom-most cell in the 2nd column on the left end of the bus wire.

4. Now on the top-most cell of the 2nd column, I should run tabbing wire from the right end of its bus wire, all the way down to the bottom-most cell of the 3rd column on the left end of the bus wire.

I think what I said is correct, but please correct me if I'm wrong.

I just hope I have enough tabbing wire left to do the job. If I don't, I could just attach some of the remaining bus wire to the end of the tabbing wire to make it longer right? Oh and if this is possible, I could also cut the bus wire in half if it's too thick, correct? I can't believe how ghetto/unconventionally I'm doing this right now haha.

Lastly, if I don't have enough room in between my columns to run the tabbing through, is it fine if it covers a very small portion of the cells? I'm assuming it should just minimally reduce the output, but should be fine.

I have never worked with homemade cell arrays myself, so I may not be the best to answer you, but here goes and others can correct me.

1, 2, 3, 4: Yes, that is what I mean. Although unless you are trying to keep it thin and encapsulate it with a close fitting glass or plastic cover, you can use regular wire for the long run. Or go though holes in the pegboard to run a long insulated wire down the back side joining the short bus wires. If either the tabbing or bus wire is too thin, then the extra resistance of the long run will cause you problems.

If you are going to overlap the cells, make sure that whatever you use is insulated from the top surface of the cells! The small shading will not matter much, but an electrical contact sure will.

[sultan316]

I have never worked with homemade cell arrays myself, so I may not be the best to answer you, but here goes and others can correct me.

1, 2, 3, 4: Yes, that is what I mean. Although unless you are trying to keep it thin and encapsulate it with a close fitting glass or plastic cover, you can use regular wire for the long run. Or go though holes in the pegboard to run a long insulated wire down the back side joining the short bus wires. If either the tabbing or bus wire is too thin, then the extra resistance of the long run will cause you problems.

If you are going to overlap the cells, make sure that whatever you use is insulated from the top surface of the cells! The small shading will not matter much, but an electrical contact sure will.

Great! Oh regular wire would make things a lot easier. I have plenty of that. I was planning to use 14 gauge wire to connect to my charge controller/battery, but would 18 gauge wire be fine for this purpose?

[inetdog]

Great! Oh regular wire would make things a lot easier. I have plenty of that. I was planning to use 14 gauge wire to connect to my charge controller/battery, but would 18 gauge wire be fine for this purpose?

How much current will the panel produce, and how long will the wire be? 18 gauge will probably be fine for less than 10 feet.

[sultan316]

How much current will the panel produce, and how long will the wire be? 18 gauge will probably be fine for less than 10 feet.

Max current is 3.6 amps and the wire inside the panel I'm assuming will be under 4 ft (almost the length of the panel itself). For outside the panel (where I plan to use the 14 gauge, I'm not sure, but I guess maybe like 20ft? I'm honestly not sure at all though. Haven't really thought about it much since this isn't too serious of a project.