Introduction: Make Modular, Pocket-Sized Solar Panels

Have you ever been outside and had your phone die? Have you ever wanted to make your own solar panels for charging a cell phone or electronics project? Now you can!

Each panel costs $1.25 in materials and provides 0 - 0.5V at 400-1000mA depending on load and lighting. The panels are linkable by magnets, and can be reconfigured on the fly to provide different voltages and currents

This is a cheap, portable device that can be used to charge your cell phone when you're camping or on a grassy knoll somewhere.

It is easy for anyone to make, with tools that you might have around the house.

For an alternate guide, check out the project's github page.

Step 1: Tools and Materials

Tools

  • Office Laminator
  • Scissors
  • Ruler
  • Non-stick parchment paper (bakery/baking/butter paper)

Materials

  • Polycarbonate sheet .01" thick - This will be the rigid, protective layer that surrounds our solar panel. I bought mine from mcmaster.com.
  • EVA (Ethylene-Vinyl Acetate) film encapsulant - This should come with a smooth and a bumpy side. It's made as a film for solar panels, and will cushion the cells to keep them from cracking. I found mine with this Ebay search.
  • Copper tape with conductive adhesive - It's important to make sure that the adhesive is conductive (most aren't). I found my tape on adafruit.com
  • Solar Cells - I recommend 52x76mm multicrystalline or polycrystalline solar cells. These will give us 0.55V open-circuit voltage, and 1A short-circuit current. I found mine with this Ebay search.
  • Small neodymium magnets (1/4" x 1/8" x 1/32") - You will need 2 for each panel you want to make. I got mine from KJ Magnetics.

For a price breakdown, see this project's github page on materials.

Disclaimer: Solar cells are extremely thin and crackable. Always handle with care.


Step 2: Cut Sheets to Size

For 52x76mm solar cells, cut your sheets to 65 x 90 mm (6.5 x 9 cm). For each solar panel you plan to make, cut two 65x90mm rectangles of polycarbonate, and two rectangles of EVA.

Step 3: Apply Tape to Front

Cut a strip of copper tape 7cm long. Apply it, sticky side down, on the white line.

Be sure that there is a gap between the end of the tape and the end of the cell (seen here at the bottom of the image)

Step 4: Apply Tape to the Back

Flip the solar cell over. Repeat for the back of the solar cell.

Be sure that there is a gap between the end of the tape and the end of the cell (seen here at the bottom of the solar cell)

Step 5: Place Plastic Backing

Take one piece of polycarbonate and remove both pieces of protective film from the plastic. Remove the protective paper from one EVA sheet. Put a sheet of EVA exactly on top of the polycarbonate with the bumps facing up. Then place the solar cell assembly on top of that.

Carefully position the solar cell to be in the center on top of the polycarbonate/EVA sheets.

Step 6: Place Plastic Fronting

Remove the backings from the remaining polycarbonate and EVA sheets.
Now place an EVA sheet with the bumps facing down on the assembly. Place the remaining polycarbonate sheet on top of the EVA.

Step 7: Laminate Your Solar Panel

Check that your solar panel is in this order from bottom to top: polycarbonate, EVA (bumps up), solar cell, EVA (bumps down), polycarbonate. Also make sure that your copper tape is sticking straight out of both sides of the panel.

Place the assembly between pieces of parchment paper to keep the laminator's rollers clean from melted EVA, and copper tape adhesive.

Without disturbing the position of the solar cell in the assembly, carefully put the assembly into the laminator in the direction shown.

Step 8: Preparing the Magnets

When working with these magnets it's important for them to be the right direction. Mark one side of a magnet. Now do it on the rest, so that when you stick two magnets together, the marked side always attracts the blank side.

Step 9: Add Magnet to the Front

Put a magnet with the marked side facing up on the panel as shown here.

Now fold the copper tape over. Make sure it tightly contours to the 90 degree angles of the magnet.

Step 10: Add a Magnet to the Back

Now turn the panel over and add another magnet where shown. This magnet should have the marked side facing down.

Now fold the copper tape over. Make sure it tightly contours to the 90 degree angles of the magnet.

Step 11: Check Your New Solar Panel

If you have a multimeter, check the voltage and current output of your new solar panel. Make sure there is a bright light shining on your solar panel. It should have a voltage of 0.55V, and a current between 0.4A and 1.0A depending on how bright your light is.

Step 12: Stack Your New Solar Panels

Because of the design, these solar panels can be stacked for easy transportation. Your panels are approximately the size of a deck of trading cards. I bought this card carrying case at tap plastics.

Step 13: Powering Electronics

If you want to charge your cell phone at 5V with USB, you have a number of options:

With 6-12 panels (3-6V) you can use a board like the Minty Boost or another 3V to 5V boost converter to charge your phone.

With 12 panels (6V), you can use Adafruit's solar lithium polymer charger to very efficiently charge a battery and your phone (may need a 5V LDO Linear Regulator).

With 12-46 panels(6V-23V), you can use a buck converter and my other guide to efficiently charge your devices.

You can run an Arduino by wiring the positive and negative leads of 12 solar panels in series into the barrel-jack of the Arduino.

Comments

author
Cole.Dickson made it!(author)2016-01-20

This is great! I want to make a large array mounted on a wooden board following this method but I would like to change a couple things. I'm going to cover the exposed copper with liquid electrical tape to prevent corrosion. Where two cells contact each other I'll use snaps that are soldered on, or magnets that stick to a washer that's been soldered on.

A couple questions :
What's the max amperage you think this copper tape can handle?
Have you noticed any flex/cracking in the cells from changes in temperature? I'm guessing your cells are too small for that to be of any effect?
How have they stood up to the elements?


Thanks so much!

author
DavidS83 made it!(author)2015-06-10

I was wondering what laminators you can use .. I did not find the cosmo 95 anyware.. I know they are limited in the thickness of items that can be laminated also what heat setting / temp can the cells handle? would any old, cheap laminator work

author
SparkySolar made it!(author)2014-10-19

Thank you for your Instructable

Nice job.

Rima

author
jcastaneda5 made it!(author)2014-09-13

So would it work if i connected them all together, lined them up nice and straight, but instead of laminating them, would they be damaged if i used a food saver vacuum and just spaced them all out so that way i could still fold it up and store it?

great ible by the way

author
rose_adamaj made it!(author)2014-04-12

You got my vote! I have been interested / fascinated with making my own phone solar charger for years. I have read so many ibles, & always been afraid to try them because: I either don't understand everything it says to do, I don't have everything needed, I am intimidated by technical terms, where exactly do I get the items needed...
As you can tell, I don't even know enough to be considered a novice! Your ible is so well done with pics, explanations, links, & you use items even I can use!!!!! You have opened the solar world to a lot of people like me. (I don't think I'm the only idiot, I hope I'm not, you don't suppose I'm the
only

author
kotasankalp made it!(author)2014-04-07

Where can you find a laminator?

author
rcvpedersen made it!(author)2014-04-08

I've seen them at office supply stores or stores that sell home office equipment. I think Amazon also sells them. :)

author
kotasankalp made it!(author)2014-04-10

ahh ok. Thanks!

author
three_jeeps made it!(author)2014-04-07

It seems to me that running the PVC assembly thorough the laminator has the risk of cracking the fragil cells.....Have you experienced that? If not, why? precautions?

Very nice concept!

author
rcvpedersen made it!(author)2014-04-08

I was also worried that the cells would crack. I've listened very closely when laminating cells and haven't heard any cracks so far. Also the power output from the panels is only slightly less than the power output from the cells alone, which I attribute to light loss through the plastic, and not to cracking.

author
electrolics made it!(author)2014-04-07

great project

please share the weight of each cell with and without encapsulation

thanks

author
nqtronix made it!(author)2014-04-03

Totally awesome idea. The modular system eliminates the need of a complicated folding mechanism.

However I've some suggestios to improve the design even further:

1. Copper stipes in combination with strong magnets offer a good electrical connection with a low resitance, but it quickly oxidizes resulting in a bad connection over time. Gold plating (can actually be done at home, but I never tried) could be a sollution

2. I like the fact, that the panels can be easiely stacked for transportation/ storage, but it would be realy neat if you could carry your "emergency power kit" right in your wallet. That would require some work though:

2.1 Magnets and credit cards are a bad combination, so solid connectors might be the only option.

2.2 You would have to find cells of the right size to match the size of a standard credit card. Thickness would be also an important aspect

2.3 The most critical problem would definetly be the fragility of the glass. I don't know if it is commercial available, but the glass could be replaced by acrylic or any other kind of plastic

3. As you pointed out in your last step it is almost always required to regulate the voltage produced. That said, the set of solar cells should definitly include some kind of step-up/-down converter to archive the highes efficiency possible. Preferably it should be the same size to stack nicely.

For anybody in interest, I did some research on low-voltage step-up converter IC's about two years ago. I figured out the max1703 (datasheet) is great at boosting low voltages at high output currents at a high efficiency (in 1,2V; out 5V; output current 200mA; efficiency 88%). Sadly the chip isn't cheap at all, it costs 12,33$ @digikey.com, all aditional parts excluted. But, if you couse the right parts, the build height can be reduced to 2mm, including a 0.4mm circuitboard. I left this project unfinished, but I save all links (a few dozen) and i'll send them anybody who wants them.

Oh, and thanks for sharing your project with us :D

author
lobalt made it!(author)2014-04-07

2.1 - Mythbusters disproved the magnets vs credit cards myth. You have to have a ridiculously powerful magnet to have any effect on a magnetic card strip and the tiny magnets used here don't fit that bill. :)

author
rcvpedersen made it!(author)2014-04-03

Thanks for all of the suggestions!

1. That a really good point. I'll have to investigate how quickly that is happening. Perhaps a cleaning product could also be used to remove the oxidation.

2. Thanks! At a friend's suggestion, I constrained them to fitting in a purse. They'll fit in a pocket as well. With fewer, smaller cells, I could see it fitting in a fatter wallet.

2.3 I've actually looked into thin glass (gorilla glass, et al.) and found them to break the bank compared to the polycarbonate plastic I use, even though the glass provides better scratch protection, and is probably more rigid.

3. That is a great find! It'd definitely be super useful to be able to do low-current 5v things with 3 panels, instead of the 6 minimum needed for the converters I mention.

And finally, it was my pleasure to share! My one hope is that people will go out and make them!

author
nqtronix made it!(author)2014-04-03

Instructables somehow managed to mess up the link to the datasheet. so here you go: http://datasheets.maximintegrated.com/en/ds/MAX1703.pdf

author
Treknology made it!(author)2014-04-05

Damn good idea! It is seriously time that PV cells started turning up on products in the same way that it was fashionable to fit an LCD clock to everything from pens to rulers. For years now we've had calculaters with PV that work quite well under normal artificial light, so why don't other appliances collect their energy in the same way?

author
legamin made it!(author)2014-04-05

I ve used a silver solder connection (ruined a few panels before getting it consistant) then built weatherproof glass faced flat cabinets that could be mounted on a tracking system. I have a 48 volt system that uses a transformer and deep cell marine batteries to supply round the clock power to our hot tub entertainment area outdoors in the villa. Glass cleans up and the system has 6 years of proven supply with no evident power loss or deficit of battery life. The system can be slapped together in a couple of weekends.

author
rcvpedersen made it!(author)2014-04-05

Nice! Your setup sounds really awesome! I was shooting for something one could carry in their pocket so picking materials was a tricky balancing act between price, weight, and size. I ended up going with different materials than solar assemblies usually use in an effort to have the panels fit these constraints.

author
ZacWolf made it!(author)2014-04-03

Great stuff!

If you could think of a durable hinging connector such that they fan-fold in and out of the box that would make both setup and storage really easy! I bet you could take brass hinges, take the pin out, and then replace two of the "teeth" with small copper pipe (you can find these at craft stores in the jewelry section), soldering your copper tape to the new hinge teeth. It would probably be tedious work, but being able to pull the top cell out and have the rest follow would be pretty sweet. :)

Question. Did you do any kind of electrical test of the cell before and after lamination? Curious how much the lamination material reduces the electrical output. Would love to see you post stats of the output a year later. :)

author
rcvpedersen made it!(author)2014-04-03

Thanks! I think making them foldable is a great idea! I had been thinking about using conductive fabric to do exactly what you're proposing. The stumbling block I hit there is that the junction needs to be of extremely low resistance to not dissipate the 0.5V generated per panel. For example, 0.5ohms would dissipate 1A of current at 0.5V. That constraint reduces the materials that can be used.

If the hinges were mechanically connecting the two panels, and mechanically pressing the copper tape from the panels together, I could definitely see that connection being low-enough resistance.

I'm curious about the output a year later as well! The polycarbonate should yellow in about 7 years of year-round sunlight exposure. I think the EVA is pretty UV resistant, given that a staple of solar panel manufacturing.

I've measured the output before and after lamination before, but I only remember it wasn't significant. I'll definitely keep track of their output over time.

author
ZacWolf made it!(author)2014-04-04

What about using a tough non-conductive cloth (nylon?), and just stick the copper foil tape to that to make the connection? Maybe reinforce the whole thing by doubling the fabric with its own bit of conductive tape so they are sandwiched together. If you ran a single stitch down the center of both pieces of the overlapping foil, that'll give you multiple points that would have to fail. Anyways, great stuff!

author
rcvpedersen made it!(author)2014-04-04

Yeah! The trick there would be seeing how many times the copper tape could be bent back and forth before it snapped. Definitely something I'll check out, though.

author
razamatraz made it!(author)2014-04-04

This is a cool way to do it. I think I have about 30 3" square cells in a box that I might try this with. Thanks for the idea.

author
maruawe made it!(author)2014-04-04

looks good

author
agis68 made it!(author)2014-04-04

very creative instructable

author
jjsims made it!(author)2014-04-03

very cool idea.

author
billbillt made it!(author)2014-04-03

got my vote

author
billbillt made it!(author)2014-04-02

great idea

author
querry43 made it!(author)2014-04-02

This is fantastic! You could absolutely sell these. What do you think about adding snaps or more magnets to make the interconnects more durable?

author
rcvpedersen made it!(author)2014-04-02

I've thought about snaps as well. Small snaps could work because they would conduct as well as mechanically attach the panels. More magnets is a great idea too! One mod could be to have two magnets on each side of a panel to make each connection stronger. Two more magnets per panel would add about $0.30 to the cost of each.

author
ajchernik made it!(author)2014-03-11

I tried this project and it was really easy! And actually worked! It was so cool to see my cell phone charging. Make sure you have direct sunlight or a bright lamp for it.

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