Instructables

Five minute solar phone charger

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Picture of Five minute solar phone charger
Need to charge your phone?  Have nothing but a clothespin and some P-N junctions?  Have no fear!  The (solar) power is in your hands!
 
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Step 1: The Big Idea

Picture of The Big Idea
So, what's the plan, stan?

Well, we're going to make a solar panel from scratch that can charge up a simple phone.

See, cheap phones like mine are real simple to charge--they just need 5V and they'll take care of the rest.  They'll draw as much power as they can (my little nokia will draw up to an amp while charging), but they're smart enough to limit their current draw to whatever the source can provide.  

So, that means we need to make a 5V solar panel.  Solar panels are made by wiring up a set of solar cells--big silicon P-N junctions.  A solar cell puts out a very low voltage--0.65V open-circuit, or around .55V under an ideal load.  To get the 5V that we need to charge a phone, we have to wire up a bunch of solar cells in series.  

But how many solar cells?  Well, a solar cell without anything connected to it will produce .65V in bright sunlight, but as I draw power from the cell, the voltage will drop.  This relationship is called an I-V curve.  The max current the cell can output is based on the area of the cell, the intensity of the sunlight and the temperature of the cell, but the max voltage is always the same, regardless of the size of the cell.  
Every solar cell has a peak power point, a current-voltage combination that gives me the most possible power for that cell.  For my panel, I want to run my cells at their peak power point.  I happen to know that the peak power point of my cells is .5V at 130mA.  So, if I want to put out 5V, I need to stack up at ten solar cells in series, giving me an output of 5V.  If I'm drawing less than 130mA, my output voltage will "float" up, and if I draw more, my voltage will get pulled down.  Now, it so happens that phones are pretty smart and robust, so I can actually give them a bit more than 5V, and they'll be fine.  I'm actually going to add an extra cell, giving me a total of 5.5V coming off my cell.  This makes my panel a little more robust--the higher voltage means that, in lower light, it'll still put out enough voltage to charge up my phone, and it'll be less sensitive to shading or pointing it away from the sun.  

So, I'm going to make a solar panel with eleven solar cells in series, I'm going to wire the output into a phone, and it's going to charge.  Cool, right?  It's pretty quick and easy to do, too.  Here's a video of the whole process:

Step 2: What you need

Picture of What you need
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This is a pretty easy and cheap project.  You need:

Solettes--cut up pieces of solar cells.  You can get them as part of a DIY solar kit that a friend and I put together, or pick some up on ebay by searching for "solar cell pieces", like these:  http://goo.gl/C25he.

a cheapo phone charger that fits your phone.  Mine was a nokia, and I got a knockoff charger for $2.

Copper tape--available at michael's, Sparkfun (http://www.sparkfun.com/products/10561), and plenty of other places online, for cheap

A clothespin


and wire strippers, scissors and a soldering iron.  Ready, set, go!

Step 3: Tune out, Build up

Picture of Tune out, Build up
To build anything, you need some proper tunes.  Did you know that Scarlett Johansson put out an entire CD of Tom Waits covers called Anywhere I Lay My Head.

Kill me now Pete, I'm in heaven

Step 4: The ol' strip-n-cut

Picture of The ol' strip-n-cut
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Chop up that purty phone charger.  Cut the charger part of it, so you're just left with a nice long cable and a phone connector at the other end.  Strip the ends of the wires.  

Step 5: Coppertape

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Cut a couple of small pieces of copper tape, just a little longer than the pads of the clothespin.  Solder each wire from the charger to the end of a piece of tape.

It's like you made an adorable little heart resuscitation device for tiny little mice having cute heart attacks

Step 6: Stick that where the sun don't shine

Picture of Stick that where the sun don't shine
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Now you're going to stick the tape onto the clothespin pads, with the wires coming out of the back of the clothespin.  I found this to be challenging, but not too hard.  Just right, really.  Persevere!

Smush the clothespin together to stick the tape on well.  It's like you made a little electrical alligator!

Step 7: Pick a cell, any cell

Picture of Pick a cell, any cell
Now for the fun part.  Stack up the solettes, and then fan them out like a deck of cards.  Stacking them up makes a series connection between each of the cells, and now we just need to attach to the top and bottom of the stack to pull the power out.  

Fan them out pretty wide--the better they're spaced out, the more each solette will show, and the more current you'll be able to pull off the panel.  

Now fan yourself and talk about mint juleps in that adohrable suthehn gentlmuhn accehn yuhv been a-wohkin on

Step 8: I pinch!

Picture of I pinch!
Now, clip the clothespin onto your fan.  It takes mighty skill to do so without breaking the solettes or ruining your delicate fan arrangement.  Stop complaining.  Sack up and do it.

The positive (usually red) wire going onto the bottom of the stack of solettes (the side that's not blue), and the negative wire goes to the top.

Step 9: And they charged happily ever after

Picture of and they charged happily ever after
Sweet, you're done!  Plug your phone into the charger and go wave the panel in the sun.  Shout excitedly to all your friends and then go hug a sad banker.  You've powered something FROM THE SUN!
kornedo5 months ago
kano ung copper tape?? tsaka..bilang cell gamt mo
owald19 months ago
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echauz999 months ago
where can i buy the solar cells??? ps i live in manila
sanchitkhera710 months ago
Any chance of damaging the mobile phone? Does it work for smartphones too?
I am fairly new to Instructables so I will have to take a look at putting it together. I definitely want to get a video up. I'll let you know when I get either up. (I tried replying but the captcha thing seems messed up)
Fhev1 year ago
sir, anu pa pwedeng ikapit sa clip bukod sa copper tape? anu ba pwedeng applicable bugod sa copper tape? pwede din q ba gamitin ang universal charger cable? iisa din lng ba xia? kung saka sakaling ganun gawin q, mas mgnda diba?
JensonBut1 year ago
I made these last night and the were delicious BUT the flattened out...
Gigean1 year ago
Is it possible to do make this for a smartphone? Is it recommended? I'm looking for a way to safely charge my Android phone
prank (author)  Gigean1 year ago
Sure! The charger I make in the instructable just outputs 5.5V at ~100mA. If you slap the appropriate USB connector for your smart phone onto the alligator clips, there's a good chance it'll power it up. It depends on your smartphone--some phones will be more finnicky about their power, but you won't hurt it. I say give it a shot!
prank (author)  Gigean1 year ago
Sure! The charger I make in the instructable just outputs 5.5V at ~100mA. If you slap the appropriate USB connector for your smart phone onto the alligator clips, there's a good chance it'll power it up. It depends on your smartphone--some phones will be more finnicky about their power, but you won't hurt it. I say give it a shot!
rimar20001 year ago
Very clever design!
lwillen1 year ago
jesus-i cannot see the clip because in germany it is blocked because of music copyright
prank (author)  lwillen1 year ago
Try this: http://www.youtube.com/watch?v=A_Rz1Y_dVvg

It's the same video, but with creative commons music. Another guy, also from germany, had the same problem. I learned my lesson--all movies I put up from now on will have cc soundtracks.

--me
Super cool!
Can't wait to do that tomorrow. Every day sun in the Philippines. (almost every day). But the problem the solar panel.

Thanks.

"...or stay tuned for a DIY solar kit kickstarter my friend and I are launching soon"
when???????????
prank (author)  Paulus441 year ago
Saan nakatira ka sa pilipinas? Nakatira ako sa maynila!

Kickstarter kit is coming August 15.
Hey cool you're in the Philippines?

Where can I buy them here? I'm in Bohol but I'm willing to get to Cebu or Manila to buy a bunch of these and make with my friends and family here. What Filipino doesn't use these Nokia phones? lol

Salamat!
prank (author)  filipeanut1 year ago
Hey Filipeanut,

We're running a kickstarter right now, and kits of solettes are one of the rewards. Check it out at http://www.kickstarter.com/projects/alex9000/the-solar-pocket-factory-an-invention-adventure.

Salamat naman!
Paulus44 prank1 year ago
Im from Netherlands and live here. Only english pls.
Thanks
Translation of the above. "Where do you live in the Philippines? I live in manila!"
I do live in Cagayan de Oro but this week we have a lot of clouds and rainy days. Anyway I have already the solarcells, but the coppertape was more difficult. But I found some scrapcopper and can use that. Tomorrow I make it and there are already some people from the mountains who will buy one.
I also read in the newspape that there there is a T-shirt what has a special procedure and it also work as a charger when you wear it. A wire from the T-shirt to your cellphone and your CP will be charged via your t-shirt.
Amazing.
I live in Singapore! Sun everyday too!
gemtree1 year ago
The copper foil tape can be found where they sell stained glass supplies, usually in different widths.
brintxin1 year ago
Tremendous instructable!

Please does anyone know wher to buy these wafers ? - I just can't find an outlet on the net.

Thank you.
prank (author)  brintxin1 year ago
The ebay link from the materials page shows a bunch of places you can buy them. And we're releasing a kit on kickstarter in two weeks. Stay tuned!
brintxin prank1 year ago
Thanks, but on the display I cannot see a materials page. I only see photos and the text and their are no links there.
I look forward to the kit.
prank (author)  brintxin1 year ago
Here you go--I should have made this an actual link. http://goo.gl/C25he

You can get the solettes from various guys on ebay, taobao, aliexpress, or anywhere else you search for "solar cell piece"
noahh1 year ago
If anyone is looking for copper tape, it's often sold at hardware stores in the pesticide section because it repels slugs.
mysss1 year ago
Awesome. So I take it a smart phone would likely be less robust?
chantie31 year ago
Do you think this would work safely and not break my iphone4? Thanks, Mary
Hi Mary,

This project won't "break" your IPhone as the iphone will simply say charging device not recognised. this project currently won't work for newer iDevices as they require a special circuit.

To quote Chunkyhampton
"Actually, charging Apple's devices is a little more complex than just supplying 5V on the USB port. You must also tell the device how much current to draw. This is done by supply a potential to the D+ and D- lines, using a couple of resistors.
This was reverse engineered by and is explained in detail by Lady Ada here:
http://www.ladyada.net/make/mintyboost/icharge.html
and also a bit on my attempts at doing it here:
http://www.re-innovation.co.uk/joomla15/index.php?option=com_content&view=article&id=167:voltage-regulators-a-go-go&catid=48:blog&Itemid=75"

So yeah hope this helped
actually these solar cell's are available which require for charging and all, at various sites,

dealsbookie.com, ebay.in also one of the sites where you can get solar cells
6v 100ma, 6v 200ma, 7v 100ma, 3v 100ma
resin laminated, cabinet, small kit, soldered with clip all available at just 4-6$

can charge mobile phone by that, even can charge AA AAA batteries, can make solar lantern's and all
prank (author)  graghavendra1 year ago
You can definitely buy pre-made solar panels anytime you like. This instructable is about a different way of making them yourself. It's not a replacement--it's an alternative for anyone interested in what goes inside those pre-made panels.

I started experimenting with making my own small solar panels after I was dissatisfied with the existing resin-laminated panels--I was finding panels with shorted solettes, putting out a lower voltage than I needed, the resin would yellow in the sun after a couple years, making the whole panel unuseable, and after looking into how the panels are made, I started wondering if there could be a better way to make them.

Now, I'm not claiming that this instructable is a better way to make solar panels. There are plenty of flaws with the fanned design I used here. But it's just cool to make your own solar panel from scratch, and I put this instructable up to share that coolness.  Because making something yourself is always more interesting than buying it.
its nice to hear back from you..

i wish to say, resource and knowledge availability is very important, which always vary from country to country..
think about the country which are growing, knowledge they have towards solar
even now, millions of people seeing solar only in books, they think its complicate, unreachable, misunderstanding concept. because of above.

and all of sudden, u can except all to do as u said, level of knowledge, understanding capability and resource and patience and support all these must required to do it.

i suggest to buy resin, cabinet at 1st, test it, be practice, become friendly with the subject, then go deep to make ur own..

and the place where i mentiond, u get cabinet one. so no worries about disadvantages of resin..

who cant do all for themself atleast let them do this, i hope if they start slowly they reach goal for sure a day, a person who dont know anything, cant get satisfactory results when he done such deep experiments

let me say some info, i m a deep hobbyist, done many plenty.. still availability of these solar panel is tuff, and u mention copper tape, that too..

most are copy cat at beginning they dont use their brain to find alternative, so they think we cant do these. and drop their idea/wish
Brian9961 year ago
Just a thought: You could rivet the solettes with a plastic non-conductive rivet and attach the conductive tape to each side of the solette pack. No clip needed. Then the charger would fold up to a pocket size.
prank (author)  Brian9961 year ago
I dig it. I actually started this response about how hard it is to put a hole into solettes, and then it crossed my mind that I'd never tried circuit board drill bits.

I tried one, and after fumbling and breaking my way through ten solettes, I got it! I actually drilled a hole in silicon, to my utter surprise. I'm using a ~1mm bit that's meant for fiberglass circuit boards--it's a rando bit from an electronics store in manila, so I'd bet against it being a fancy-schmancy diamond bit or anything like that.

I dig the rivet idea--my recommendation after a bit of drilling is to do it on a perfectly flat, hard surface. If the surface can compress at all, the solette will bend, build up stress, and snap where the drill bit is pressing into it. I like drilling from the back, too--the drill bit centers in the metal screenprinted layer before it starts cutting into the silicon, and it's easier to get the hole where you want it.

With the rivets, I'd use a nice wide rivet or a washer to spread out the force, otherwise it'll be snap city.

Now I want to build a solar necklace with magnets to hold everything together!
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LOL...mouse AEDs. Your captions are hilarious.
marymac1 year ago
As clueless I am I might vote to buy a solar charger for USB devices for as little as nine bucks or a fancier one for about twenty and all in a case. The iPhone wants a lotta beef for a charge but will it ever get enough?
blancast1 year ago
On the fan design: How about adding an axis to the fam pivot...a hole through each segment and through the jaws of the clothes pin with a plastic rod running through the lot. The rod could just be mushroomed on each end with a hot piece of metal or glued.
Not only would this solidify the thing a bit and make fanning it out easier, the extra security of the attachment would make it easier to fan the pieces out for maximum exposure.
nof-z1 year ago
is it possible to use an iphone charger?
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