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

Intro: 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

STEP 2: 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

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

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!

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.

IT'S CHARGING!

STEP 6: 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.

Thanks!

Brennan

Comments

[simme_cool_swimmingpool]

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

[akbrennan]

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.

PLEASE BE AWARE:

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]

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

http://ezrd.me/r/?rd=083K7OGCE ? 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]

neat

[mueblesdejardin]

It is interesting, but maybe a little too big

[mutlu.teker]

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

It is very dark in the photo.

[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 :)))