Introduction: How I Built a Solar IPhone Charger for Under $50.

Picture of How I Built a Solar IPhone Charger for Under $50.

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I am not responsible for any damage that you may cause to your iPhone or any device that you use with this charger. I can not stress the importance of checking your circuits with a multimeter enough, and I can assure you that I've done so at every step in this build process. Your phone is a very expensive device. Treat it like one!

Intro and Design:

Over the past month or so, I've been working on designs for a stationary solar iPhone charger. By stationary I mean a charger that will be kept in a fairly permanent place. I bring mine with me if I'm going to be camping or staying somewhere for a while, but it's really not meant to be portable.

This isn't only a solar iPhone charger. You can use it with any device that will charge via USB. I just happen to use it to charge my iPhone. Also, this design doesn't include a battery in the circuit - which means that you'll have to charge your iPhone when the sun is out and shining. I know it's a serious inconvenience, but adding a battery makes the circuit much more complex - and is a bit more costly. I'll be following up this design with an update on how to add a battery conveniently into this circuit.

The idea behind this panel is that it's simple (and cheap!). You don't have to have any prior circuit knowledge,or familiarity with electronics. I'm really just stepping out of the novice stage as far as soldering is concerned, so this is a great beginner project for just about anyone!

Step 1: Tools and Materials

Picture of Tools and Materials

As I say in the title, I built this charger for just a bit less than $50. That doesn't include the cost for tools and a few of the materials that were salvaged, but if you spend enough time on eBay you should be able to build yours for the same amount, if not less.

Let's take a look at what was used to build the panel.


Soldering Iron w/ Solder and Flux
Needle Nose Pliers
Wire Cutters/Stripper
MultiMeter (IMPORTANT)
Materials and Prices:

Part/Material ------------------------------------- Source ----------------- Cost

10 Watt Solar Panel ----------------------------- eBay -------------------$41.45 w/ shipping
7805 5Volt Regulator ---------------------- RadioShack ------------- $1.59
iPhone/iPod Cable ------------------------------ eBay ------------------ $1.20
USB Extension Cable -------------------------- eBay ------------------ $3.00 w/ shipping
Red/Black small-guage wire --------------- On Hand --------------- Free
Electrical Tape --------------------------------- On Hand --------------- Free
Small Zip Tie ----------------------------------- On Hand --------------- Free

Step 2: The Panel

Picture of The Panel

This Solar Panel is a 10W panel made by LaVie Solar. You can check out their website, but your cheapest bet is to use eBay. Their eBay user ID is lavie-inc. I snagged a pretty great deal at $41.45. The panel has a really sturdy build quality. It has an aluminum frame, and seems to be entirely weatherized. I wouldn't have too much of a problem leaving it in the rain. Also, All of the wiring has been done for us which saves a LOT of time. They even put a blocking diode into the connection on the back, so we don't have to worry about that in our circuit.

The panel has an output rating of 21.6 Volts (Open Circuit) and .62Amps (Short Circuit). These are optimal ratings, but when I tested my panel in direct sunlight, that's almost exactly what I got.

As far as efficiency goes, this is not the ideal panel to be using as a direct USB charger. We'll be loosing a lot of energy as heat when we regulate the 20V output down to 5V to match USB standard. However, using a larger panel means that there will be more current flowing even when there's not a lot of sun. I've even seen my iPhone charging when the solar panel is in the shade!

Step 3: The Simple Circuit

Picture of The Simple Circuit

After gathering all of the materials, I sat down and got to work.

I cut 2 pieces of Black wire and 2 pieces of Red Wire. The lengths were around 5-6 inches. Then, I cut a little bit less than an inch off both ends of each wire.

With my black and red wires ready, I cut my USB extension cable in half and stripped the cut half of the female end to expose all of the individual wires. There are 4 wires in all USB cables- Green, White, Red, and Black. The Green and White wires are for data, so those are not needed. I snipped the Green and White wires, along with all of shielding and fiber - leaving only the Red and Black wires coming out about an inch and a half from the USB cable. I stripped a little bit less than an inch off the Red and Black wires on my USB extension.

Since the 5V regulator only has one Ground pin, I used the two black wires that I cut initially- to make the soldering a little bit easier. I took both of my black wires, along with the black wire coming from my USB extension, and twisted them all together carefully and securely. I put some solder on that connection to make sure that all of the wires stayed together. Then, to keep things safe, I covered the 3-way connection with electrical tape.

Once all of the wiring was prepped, it was time to put the 5V regulator into the equation. Soldering wires onto the tiny pins from the 5V regulator can be a task. I used a small Zip Tie to hold my wires to the 5V regulator to make things much easier. It really helped - I was able to do pretty clean solder jobs on each of the pins. Since neither of the red wires were connected to anything, it didn't matter which ones I soldered to which pins. Just make sure you know that if your 5V regulator is laying flat, the input pin is on the bottom, and the output pin is on the top!. I also bent the pins in opposite directions to keep everything separate.

The fantastic part about this charger is that we're already done with our circuit. Once I was done soldering to my 5V regulator, I connected the Red wire from the Output pin on the regulator - to the Red wire coming from my USB extension cable. Now, I only had 2 wire ends left. A Red wire connecting to the input pin on my 5V regulator, and a Black wire connecting to the regulator's Ground Pin and my USB extension cable.

Step 4: Connect the Circuit to the Panel

Picture of Connect the Circuit to the Panel

Since the LaVie Solar Panel has a pretty simple connection panel, pinching the Black and Red wires to the right screws on the panel was easy!

Step 5: Test the Charger!

Picture of Test the Charger!

I used my MultiMeter to measure my Input voltage that was going into my 5.00V regulator. about 20V @ 0.50A Good!. Then, I measured the output voltage coming from my Regulator. The reading was 5.00V @ 0.50A Perfect!. Those readings meant that everything was working correctly. Watch out, that 5V regulator gets hot when electrons are flowing through it!

Fully convinced that everything was working as it should be, I covered all of my open wires with electrical tape, took a deep breath, and plugged my iPhone in.


Step 6: Conclusion

Picture of Conclusion

In future designs, I'll definitely be adding a battery so that you can charge your devices at a more convenient time. I'd also like to make a more portable version of this charger. With all of the new solar technology, flexible panels are bound to cheapen up sometime!

If you have any questions, please leave them in a comment.




simme_cool_swimmingpool (author)2016-06-28

Can't you just use this to charge a batterybank instead? Then you don't need to include a battery in your circuit :)

akbrennan (author)2015-03-17

Hi folks, thanks for all of the comments! It's been over five years since I posted this tutorial. Since 2009 a lot of great solar cellphone chargers have been released. I really like the ones made by a company called Goal Zero.


When I made this tutorial I had very little electronics knowledge. This charger will work, but with the solar panel I used it's highly likely that you could burn out your 5 volt regulator (and possibly fry the charging circuit on your cellphone). The solar panel is putting out way more power than is needed. Please look for newer tutorials with more thoughtfully designed circuits.

eureka.gomez.35 (author)2015-01-05

Very creative , but don't you think it would just be too big. This might be very useful . But is it okay if I use this lightning usb data cables that is still compatible with iOS 7 or iOS 8 something like this one ? It is my extra one so that I don't need to buy another one. I will let my husband do this and will keep you updated. Thanks!

I use a 1m long data cable so that my phone can still be put indoor without being exposed directly under the heat of the sun.

SparkySolar (author)2014-10-17


mueblesdejardin (author)2014-10-14

It is interesting, but maybe a little too big

mutlu.teker (author)2014-08-18

Hi, can you give some info about how you connected the diode.

It is very dark in the photo.

jscript (author)2013-03-16

What happens if the regulator gets too hot and burst? Will the iPhone get 20V? That is a dangerous voltage for a smartphone, right?

Sassah122 (author)2013-01-28

This is waaay to expensive and complex. You can buy small solar panels for your car and modify them. I got a cheap sunlight - 12 volt soler panlel for $16. Then you just get a car power to usb adapter and attach it to the solar panel. Then just plugin your iPhone usb into adapter and you are good to go. I had my charger up and running for about $20 and in about 2 hours.

Hanssc Hafer (author)2012-12-25

you don't need to manage or buy all these tools!!!
look at this DIY Solar Panels Blog
you can simply buy it at the cheapest rate from here

punith420 (author)2012-09-29

dude you get a solar charger in e bay for Indian rupees 800 tat will be 20 dollars

Thundermoon99 (author)2012-07-27

get 4 of these there $7 a piece 3 watts each

RazorConcepts (author)2009-09-23

A better alternative would be a LM2949 or 2954 low dropout regulator, 7805s are very wasteful

westfw (author)RazorConcepts2009-09-23

won't help too much, since it's not an app needing low dropout. It's not that the 7805 is particularly inefficient, it's that LINEAR REGULATION is going to be inefficient in this case. You could use a switching regulator module like, but it would add to the price. Or you might be able to find a ~6V (nominal) solar panel (cheaper) and use that with an LDO...

Like the author said (sorta), the most efficient setup (price-wise) may not be the same as the most efficient setup (electrically.)

qwerty156 (author)westfw2012-07-23

car charger are usually of the switching kind and are far far cheaper.

billgeo (author)westfw2012-07-20

Switching regulators are the way to go with those small panels.
You want to squeeze every last mA out of the whole circuit there!

mrdudej (author)2012-07-16

Is there a way to make it work with this ?

speedfreak007 (author)2012-06-22

Also, is there a cheap way to implement a maximum power point tracking algorithm? Because the phone will draw more or less the same current (0,5 amps if you use usb charging), regardless of the irradiation. When there's not much irradiation, the voltage will lower and can prevent the voltage regulator from doing it's work properly. The charging rate should be limited when there's not much sunlight. How can i do this? Thanks!

speedfreak007 (author)2012-06-22

ou're regulator wastes 75% of the power coming from you're panel as it's, but you bought it because it's cheap, right? I've bought this one:

i did not care to check if this is a buck converter which won't waste energy because i thought every regulator works like this :) By closer inspection of the spec sheet, i assume this is a buck converter, but i'm not sure. Can someone confirm this? Thanks!

mrmerino (author)2012-06-11

I wonder if you could transform the output down to 5 volts, and then you could connect like four devices in parallel.

ASCAS (author)2012-03-06

The 7805 only limits the regulated power supply by 1 ampere, probably this wouldn't work with the iPhone 4S nor the iPad. But it's a good guide though :)))

garren11 (author)2012-02-22

Im planning on downsizing this and including a battery for it. My concern is what would be the chance of it potentially short circuiting the iphone if there is any chance at all. All help is appreciated.

Asmodeo (author)2009-09-22

Nice instructable!
I was thinking about something like this to recharge my cellular phone....
The regulator goes "hot" because the formula to calculate the disipated power is:

P=(Vin - Vout) / Iout
In your circuit:
P = (20v - 5v) / 0.5A = 15v / 0.5A = 30Watts!!!

Go get a heathsink for your poor regulator!

You possibly could use a 12V solar panel, with 0.5 Amperes output current, and the dissipated power would be

( 12v - 5v ) / 0.5A = 14W ...still in need of a heathsink...

I don't know if there are 9v solar panels.....

Wrong. P=IE, not P=I/E, so P out(max) is 7.5W

ctfjustice (author)Asmodeo2009-09-22

Hello Asmodeo, just a quick little blurp about you wondering if there were any 9 volt solar panels out there. Harbour Freight sells a neat little solar charger with battery power as well for around $12, not bad.

DarkStarPDX (author)ctfjustice2009-09-22

Yo! I just picked up the "1.5 Watt Solar Panel w/Auto Lighter Adaptor" from a Harbor Freight store for $14.99. My plan is to build a USB charger as well, however I'm going to desulfate a 12 volt hobby battery (7 amp hour) and use that to capture the daytime sun, and then charge my USB devices at night.

After I make my prototype, hopefully I'll buy another to put together an instructable, but a sneak preview includes me using 5 volt switching regulators instead of 7805's (linear regulators). You can get the switching regulators from Dimension Engineering. Another problem I need to work around is moving the solar panel "smarts" from the "auto lighter adapter" to the inside of the actual solar panel.

Lookin' great, keep it up!

lloydrmc (author)DarkStarPDX2010-11-20 has the Murata switch mode regulator

bananafred (author)Asmodeo2009-09-24

Just so you know, 15v at 0.5A is 7.5W, not 30. You multiply, not divide.

Asmodeo (author)bananafred2009-09-24

OUCH! YES, you´r right!!! but....I made you think. huh!

DraakUSA (author)Asmodeo2009-09-24

You should have spotted that since it's only a 10W solar panel. ;-)

lloydrmc (author)DraakUSA2010-11-20

Darn, I thought that he had cold fusion or something going there.

akbrennan (author)bananafred2009-09-24

Yes it is! I wondered where he was getting 30W, from calculation of a 10W panel... Thanks for pointing that out! Brennan

ctfjustice (author)Asmodeo2009-09-22

Sorry, I forgot to mention that it has several different settings for different voltages. They are as follows, 3, 6, 9, 12 volt configurations. I got it just to tinker with, works pretty well for my purpose and curiousity.

akbrennan (author)Asmodeo2009-09-22

Thanks guys! @Asmodeo - There are 9V panels. However, this was the best one that I could find for the price. As I mentioned, it's certainly not the most ideal for charging via USB, most likely it was made for charging 12V batteries. I was considering building my own custom panel, which would be the most efficient - but this was the easiest and fastest method, which makes for a good instructable for beginners. I'll continue to document my projects. Thanks for your comments!

monkyDJ (author)2011-10-11

Do you need more then 10 w???

monkyDJ (author)2011-10-06

I hope this works man, because I doing this for a project and I need to get a good mark!!! lolz

ginbot86 (author)2011-09-01

Instead of a linear regulator, you could pick up a switched-mode PTH08080W from Texas Instruments. They offer sample parts free of charge, and even shipping is free. These offer over 2 amps of current compared to one of the linear regulators, and is adjustable with a simple potentiometer.

peppero (author)2011-07-10

i have a problem my phone not charge but discharge and the same for the mp3 player how it's possible?

sdobbie (author)2011-05-19

There is a much quicker way to do this. If you got a usb car charger and connected it to the solar panel you would have a more efficient charger. Car chargers accept voltages from 12 to 24 volts usually.

Phoenixmill (author)2009-09-22

What works for some good low voltage Solar panels are the Garden lamps that people use to line their driveway. you can ghetto rig those together to get really low voltages, or really high ones. you would be surprised at how many people have broken garden lamps they are willing to get rid of.

schoonovermr (author)Phoenixmill2011-04-01

if you decieded to use one of those, would you need the same parts and everything?

lloydrmc (author)Phoenixmill2010-11-20

Good idea!

ReCreate (author)2009-09-24

I recommend you strap the Voltage regulator to something, It may overheat while the i-phone sucks electricity through it. Though they do have thermal shutdown to prevent them from burning themselves up.

lloydrmc (author)ReCreate2010-11-20

7805s do indeed have heat overload circuitry, as do, no doubt the murata switching version that's a drop-in replacement.

butterflypoo (author)2010-04-09

This seems awesome! I am not sure if someone already mentioned this in the comments, but isn't it bad for electronics to be exposed to too much light? Someone told me that once and you can even read it on the back of the packaging. Simple solution: cover up that iphone with an empty dark container (as house to keep it cool)?

I am gonna try tackling this project this summer!

lloydrmc (author)butterflypoo2010-11-20

Uhh - if I wanted to keep something cool outdoors, I might use something white or even reflective.

krimb1 (author)2010-04-25

 What a great guide! Really sturdy, and the built-in blocking diode is really awesome.

One question though: this setup won't trickle charge the iPhone after it's fully charged, right?

lloydrmc (author)krimb12010-11-20

I seriously doubt that an iPhone counts on the charger to do anything. The charge circuitry is going to be in the phone.

lloydrmc (author)2010-05-17

Try the Murata 78SR regulator.  It's a drop-in replacement for the 7805, except that it's switch mode, can handle two amps, and is much more efficient than the linear mode 7805, to the point that it doesn't even need a heat sink.  I wouldn't sweat the higher current - the unit will draw what it needs.  I would do the resistor hack, though.

jackzylkin (author)lloydrmc2010-09-20

WOw I never heard of that part -- sounds great

lloydrmc (author)jackzylkin2010-11-20

It's not even expensive. Try

About This Instructable




Bio: Hi there, I'm Brennan! Geek from Alaska, now in Colorado. I love hacking together electronics. Poorly.
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