How I built a Solar iPhone Charger for under $50.

To see my personal site with these tutorials and news, please visit http://www.BrennanZelener.com

**DISCLAIMER**

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

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.

Tools:

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

---

Comments

[jscript]

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]

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]

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]

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

[Thundermoon99]

get 4 of these http://www.siliconsolar.com/6000ma-3w-commercial-solar-cell.html there $7 a piece 3 watts each

[RazorConcepts]

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

[westfw]

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 http://www.dimensionengineering.com/DE-SW050.htm, 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]

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

[billgeo]

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]

Is there a way to make it work with this ?

http://www.mec.ca/AST/ShopMEC/HikingCamping/BatteriesChargers/PRD~5029-549/powerocks-stone-mini-power-bank.jsp

[speedfreak007]

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]

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: http://www.ebay.com/itm/270959601119?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_3676wt_1192

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]

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

[ASCAS]

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]

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]

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.....

[solaralternatives]

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

[bananafred]

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

[Asmodeo]

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

[DraakUSA]

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

[lloydrmc]

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

[akbrennan]

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

[ctfjustice]

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.

[ctfjustice]

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]

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]

Mouser.com has the Murata switch mode regulator

[akbrennan]

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]

Do you need more then 10 w???

[monkyDJ]

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

[ginbot86]

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.

http://www.ti.com/product/pth08080w

[peppero]

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

[sdobbie]

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]

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.

[Schooniedude]

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

[lloydrmc]

Good idea!

[ReCreate]

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]

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

[butterflypoo]

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]

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

[krimb1]

 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?