Help with a Little Project & Understanding the Materials Involved

[doadcma]

I think I see where you are getting off track. There are basically two PV cell types.

1. Silicon is the primary type used as it is the most efficient, reliable, and last a fairly long time. Each cell is for all intent and purposes is a very thin delicate slice of GLASS of 4 x 4 or 6 x 6 inches. They have to be protected in a glass laminate and rigid frame. These are the type DIY like yourself can get and try to build a panel.

2. Thin Film uses a special type of Ink or Paint they layer on to a substrate like a sheet of plastic film. It is flexible and can be molded. DIY cannot build them.

So if I get this right you want to use Silicon cells to make a flexible panel? The answer is No Way, its very fragile glass. As any DIY has found out, you have to buy twice the amount of cells to make one panel because they break half of them just soldering them together and get laminated before breaking them.

Only way to do this is with Thin Film panels like the one you have pictured. There are a ton of 2 to 10 watt panels out there an deven more already made USB chargers. Thin Film is not DIY. There are no cells to buy and assemble, just finished panels.

[KrazyK3nn3dy]

Ok, thank you all for your help. I'll probably have more questions as I start to actually put this thing together. Thanks again, and I am always open to other suggestions if anyone has them.

[bcroe]

Bcroe; that's along the same lines of what I was thinking to test the cells. Thank you.

I live in Florida and everyone wants to pay you with sunshine (it is the Sunshine State after all), so I couldn't help but want to take it literally (I do understand that DIY generally, if not always, ends up costing more than pre-manufactured panels [not to mention the strict building codes here, so I'm not going to be trying to power my home from solar]).

Should I bother with adding bypass diodes for a small experiment? If so, how many cells should I bypass at a time (can I get away with bypassing two or should I bypass each one)? If so, is there 4Amp diodes, or is a 6Amp ok (the cells are supposed to produce 2Amp and I'm not going to be running any in parallel [unless that would be better due to faster charging with less voltage])? I HAVE SO MANY QUESTIONS!!!!

Some recommend a bypass diode for at most 18 cells; reducing the number of cells
per diode might improve efficiency a bit. I wouldn't use diodes at more than half
their rating, unless you are using fan cooling. Bruce Roe

[KrazyK3nn3dy]

Bcroe; that's along the same lines of what I was thinking to test the cells. Thank you.

I live in Florida and everyone wants to pay you with sunshine (it is the Sunshine State after all), so I couldn't help but want to take it literally (I do understand that DIY generally, if not always, ends up costing more than pre-manufactured panels [not to mention the strict building codes here, so I'm not going to be trying to power my home from solar]). God forbid anything bad were to happen here, I don't want to have to rely on anyone but myself, and I needed another hobby besides playing video games. So I thank all of you for being patient with me and helping me to better understand what I'm getting myself into. Any other words of wisdom would be appreciated.

Should I bother with adding bypass diodes for a small experiment? If so, how many cells should I bypass at a time (can I get away with bypassing two or should I bypass each one)? If so, is there 4Amp diodes, or is a 6Amp ok (the cells are supposed to produce 2Amp and I'm not going to be running any in parallel [unless that would be better due to faster charging with less voltage])? I HAVE SO MANY QUESTIONS!!!!

[inetdog]

I short them out so
the rest can work.

Ah, the infamous bypass monode.
(A single terminal device that both ends of the cell connect to.)

[bcroe]

You have to test every cell and sort them out.

The manufacture uses a test light which is equal to 1000 w/M2 and they ensure each cell meets the minimum Isc and Voc. All the rejects get sold to you. The challenge you have is using a light source strong enough to produce rated current. That window only opens for a few minutes each day at solar noon, and only if you have a crystal clear day at solar noon. Isc has to be tested in very strong light because a solar panel is a Current Source and the current is proportional to the amount of light striking the junctions at optimum angle Voc can be made with minimal light, but Isc the most important test only can be done with very strong sun light available for a few minutes a day around solar noon. When done your panel will only be as good as the worse cell in the string. Just one bad cell and it will not work. Damage a cell while assembling, too bad...

Noonday sun and no clouds can be rare here. I built this to sort out cells. They can still get broken
in assembly, but checking voltage of each under some load will find bad ones. I short them out so
the rest can work. good luck, Bruce Roe

[Sunking]

You have to test every cell and sort them out.

The manufacture uses a test light which is equal to 1000 w/M2 and they ensure each cell meets the minimum Isc and Voc. All the rejects get sold to you. The challenge you have is using a light source strong enough to produce rated current. That window only opens for a few minutes each day at solar noon, and only if you have a crystal clear day at solar noon. Isc has to be tested in very strong light because a solar panel is a Current Source and the current is proportional to the amount of light striking the junctions at optimum angle Voc can be made with minimal light, but Isc the most important test only can be done with very strong sun light available for a few minutes a day around solar noon. When done your panel will only be as good as the worse cell in the string. Just one bad cell and it will not work. Damage a cell while assembling, too bad...

[KrazyK3nn3dy]

The biggest problem is that you have no reference on how good / bad a commercial panel is compared to your new creation using the reject parts. If you have that experience up front, THEN a diy solar project has a chance of being fun or useful. Thus you are left wondering "Is it a cell problem, my tabbing or soldering skills, my diodes," and onwards never being able to reach a conclusion from which to learn anything.

Wouldn't using my multimeter aide me in determining if it were anything other than a cell problem (and determine a cell problem if it doesn't match what it was described to produce)? Like I've said in my bio, I have some experience with electricity (cars, toys, and even in the home), so I do know how to utilize a multimeter properly. It's not the most advanced one, but it at least tells me positive and negative current (polarity). So, I assume, that if I measure the cell's output on its own, then attach the tabbing wire (or whatever material would prove best fit for my application) and measure the output (each and every time), it should clue me into whether it was due to my tabbing, soldering, diodes, etc. (Just to keep someone from mentioning this: YES, I do understand that when adding material for the energy to pass through, it will reduce the output and NO I don't care about insignificant differences in the power that could possibly be related to not receiving the EXACT amount of sunlight because it is later in the day or wasn't out as long or a cloud passed by, etc.)

[PNjunction]

While I applaud your desire to learn about solar cells, the catch-22 is that it makes the worst possible *first time* project, because the materials available to you are rejects that didn't make it into a commercial product.

NOBODY sells non-rejects to the public, but there is no authority to prevent them from saying that they are.

The biggest problem is that you have no reference on how good / bad a commercial panel is compared to your new creation using the reject parts. If you have that experience up front, THEN a diy solar project has a chance of being fun or useful. Thus you are left wondering "Is it a cell problem, my tabbing or soldering skills, my diodes," and onwards never being able to reach a conclusion from which to learn anything.

The way to do your project unfortunately would be to purchase the commercial folding panel, take your measurements, then rip it apart and put it all back together with your own fabric, interconnects, wiring and so forth. Not sure you'd learn much.

As to creating things in the future - remember that all you are going to get are rejects, so you've got to garner a knowledge of how a commercially made panel performs first.

I hate to say it, but at this price-point today, an analogy would be while I love learning about batteries, I'm not making my own voltaic-piles.

[KrazyK3nn3dy]

I understand that the cells are fragile. It is only an experiment in order to learn more about solar cells (the glass type that most DIYers can and do purchase). I'm not taking it camping, hiking, mountain biking, etc. so its fragility isn't a huge concern. I'm not trying to save money or invent some crazy thing that doesn't exist. It may only be used a few times a year if more than once in order for me to better understand solar equipment, so that I may be able to create other things in the future, if I feel like it. All I want to know is if the tabbing wire is the best or a decent material to use for the project I pictured and if not, what a better alternative would be. Is EVA film a good encapsulate and if not, what would be better for my application? Also, I figure the diodes would become too hot and melt the EVA or canvas that I would be putting this project in, so what would be a good heat sink or diode rating to help prevent this? I intend on acquiring Schottky diodes as I have read that they perform the best (correct me if I am wrong).

[Sunking]

The difference isn't folding or bending.. it's between cells and panels.. correct me if I am wrong (please because I am new to this), a CELL is the singular device that collects the solar energy and turns it into electricity, a PANEL is a collection of CELLS in a series and/or parallel or it could also consist of just one CELL. There are flexible CELLS out there, I don't care for those. Here's a picture of what I am trying to accomplish:

[ATTACH=CONFIG]4608[/ATTACH]

I think I see where you are getting off track. There are basically two PV cell types.

1. Silicon is the primary type used as it is the most efficient, reliable, and last a fairly long time. Each cell is for all intent and purposes is a very thin delicate slice of GLASS of 4 x 4 or 6 x 6 inches. They have to be protected in a glass laminate and rigid frame. These are the type DIY like yourself can get and try to build a panel.

2. Thin Film uses a special type of Ink or Paint they layer on to a substrate like a sheet of plastic film. It is flexible and can be molded. DIY cannot build them.

So if I get this right you want to use Silicon cells to make a flexible panel? The answer is No Way, its very fragile glass. As any DIY has found out, you have to buy twice the amount of cells to make one panel because they break half of them just soldering them together and get laminated before breaking them.

Only way to do this is with Thin Film panels like the one you have pictured. There are a ton of 2 to 10 watt panels out there an deven more already made USB chargers. Thin Film is not DIY. There are no cells to buy and assemble, just finished panels.

[SunEagle]

This was along the lines of what I wanted to know. For example: a bare copper wire will break if bent or folded multiple times, but if it is in rubber insulation (power wires, charging wires, speaker wire, almost any kind of wire) you can bend it a LOT more and the wire doesn't break.

The reason that wire can be "folded" and not break isn't due to the insulation but the number of strands that make up the "wire".

Most house wiring is solid #12 AWG copper. It will bend but will break after a number of bending back and forth. You can get an extension cord with #12 AWG wire but this time that #12 is made up of maybe 20 or more smaller strands of wire. This bundle of wires have the ability to flex and bend and fold many more times than a solar wire before it breaks. The insulation for either a solid or stranded wire is there to keep it from shorting between another wire or ground. It is not the main reason the wire can be bent.

As for a flexible solar cell. They make them but they are not the same as the 1" x 6" ones you mentioned. The flexible cells are made from Thin Film solar material which allows it to flex as opposed to the silicon substrate ones that easily break.

I am not sure if those flexible thin film cells are available to be purchase where you can make your own panel but you might find them out there.

If you check on that Transcend solar panel you will see it is using something made by PowerFilm which is a unique type of flexible solar pane.

[KrazyK3nn3dy]

From your initial post...


Regardless of whether you use the term folding, bending, etc, you will still have metal fatigue...which means the end result will still be the same.

If you do not want to "fold" the panel, but want to "bend" it (or whatever you want to refer to it as), you are still better off with flexible thin-film solar panels, as those are made to do what you want...

The difference isn't folding or bending.. it's between cells and panels.. correct me if I am wrong (please because I am new to this), a CELL is the singular device that collects the solar energy and turns it into electricity, a PANEL is a collection of CELLS in a series and/or parallel or it could also consist of just one CELL. There are flexible CELLS out there, I don't care for those. Here's a picture of what I am trying to accomplish:

503056.solar.charger.jpg

[KrazyK3nn3dy]

Metals suffer from metal fatigue, so eventually it will break.

Is there a specific reason you want to fold the panel on the tabbing wire? Why not have two cells connected via multi-strand ribbon cable, or something similar to that?

Second option, as Sunking mentioned, would be to just buy a small flexible solar panel. You could still design and build the charger side of things, but at least your panel would work without problems.

If you insist on building the cell yourself, you will need to come up with a better alternative to connecting the cells, as eventually any metal will break after continuous bending. Try find a flat ribbon cable, or a similar flat cable that you could use to join the cells, as multi-strand cable is more forgiving at bending than metal tabs/straps/etc.

This was along the lines of what I wanted to know. For example: a bare copper wire will break if bent or folded multiple times, but if it is in rubber insulation (power wires, charging wires, speaker wire, almost any kind of wire) you can bend it a LOT more and the wire doesn't break.

[daz]

I don't want the cells to be foldable.

From your initial post...

By that I mean; would it be able to withstand bending and unbending?

Regardless of whether you use the term folding, bending, etc, you will still have metal fatigue...which means the end result will still be the same.

If you do not want to "fold" the panel, but want to "bend" it (or whatever you want to refer to it as), you are still better off with flexible thin-film solar panels, as those are made to do what you want...