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This is going to be long because I have questions for which I can't find answers and they could be hard to describe or understand. Please be paitent with me because I am new to this technology and want to learn and help others as well. I am going to attempt to make a portable solar charging system for my iphone. I have used google and the search engine here and I can't seem to find the answers for at least this question: **How durable is tabbing wire? By that I mean; would it be able to withstand bending and unbending? I want to be able to fold up my solar panel but I am concerned that the tabbing wire will break after folding and unfolding a number of times. The reason I think this way is because I know that if you bend a piece of metal over and over again, it will eventually break. **What if the panel is encased in EVA Film? Like wire encased in rubber insulation.
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Another Set of Questions
I'm planning on using 10 1"x6" Mono solar cells rated at 0.5V, 2Amp, and 0.96+Watts in a series to charge a 2600mAh power bank rated at DC 5V 1.5Amp max input and DC 5V 1Amp output max, which may or may not be charging the phone while recharging via the solar panel. My phones AC charger says Input: 100-240V ~ 50/60Hz 0.15Amp and output 5V ----- 1Amp. I would like to add bypass diodes and a blocking diode.
My other questions are: **will this supply sufficient voltage or would I be better off adding another cell or more (due to bypass and blocking diodes and/or clouds, imperfect conditions, etc.)? **Should I run a parallel series to up the Amperage or should I make it a longer series (due to lost energy through bypass diodes)? **How many cells should I bypass (I realize the more I have that I can bypass more and worry less about lost voltage)?**I know that Schottky diodes are best for less wasted voltage, but what rating would be best for minimal heating? **Good heat-sink for diode? **Is a diode safe to be encased in Eva Film due to the heat it generates? **To add to my previous post, how durable are the diodes (can their wires withstand folding and unfolding [What if they are also encased in the Eva Film])? Thank you for your help. -
Short answer to your challenge is you are trying to reinvent the wheel. Flexible and folding panels are for sale but not something a DIY can really make because they are using Thin Film substrate that is printed on a substrate like a thin peice of plastic which is flexible and pliable. You are looking for something like 20 watt Thin Film if building from scratch, or just buy you a Solar USB Charger is what you are looking for. Just convert the plug to Apple's Queer Input. Everybody use standard USB topology except Apple. Exact same voltage and current requirements, only difference is the pin-out. They do that intentionally to force consumers to buy higher price toys for their gadgets.MSEE, PEComment
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I could buy a pre-made charger but...
I don't want the cells to be foldable. and I COULD buy a pre-made one, but I want to make this myself. Just because I can. Just for the fun of it (trying to expand my knowledge and experience). As far as connecting the phone, it has a male usb end on the preexisting charger (like almost every other portable device today?) and the power bank has the female usb to which I would plug the original charging cord. All I need to know is the durability of these materials. Input would be nice, but since I have the materials on the way, I guess I will be the first to figure it out (I'm just guessing that no-one else has bent and unbent the tabbing wire more than needed to mount the cells to a solid structure).Comment
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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.Comment
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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...Comment
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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.Comment
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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.jpgComment
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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.Comment
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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.MSEE, PEComment
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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).Comment
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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.
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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.)Comment
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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...MSEE, PEComment
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