Solar Powered USB Charger (phones, MP3 players etc)

This is my take on a already well documented little project. Very simple to make and a good introduction to electronics and solar powered stuff. Works just fine too. You need to generate 5-6V to charge a phone.
You will need:
Solar panels. I used 2 panels. (3V I think )
5V voltage regulator
USB female jack/connector
Insulated wire
Soldering Iron
Epoxy or hot glue

Step 1 Bits & Pieces

Gather together all your stuff. You need to make sure you know which side is top and which side is the bottom of the USB plug and the voltage regulator so that you solder the correct pins.

The regulator keeps the power output to 5v.

Comments

[solaralternatives]

For those asking where to get the solar cell, why not salvage some from dead solar yard lights?

[ababypenguin]

Hey, thanks for a great instructable but I have a problem.
I built the charger but I don't think I am getting enough voltage. I am using two 3 volt cells and I put them under a bright spiral CFL bulb and it can hardly light a very bright LED. My phone and other devices are not being charged. Any tips?
I am going to try putting it under the sun tomorrow.

[MattCP]

Solar panels won't work under a CFL bulb. Needs an incandescent to test indoors.
How did it go in the bright sun?

[solaralternatives]

Leave it on a sunny window sill.

[ababypenguin]

Thanks for the reply,
Okay, I'll stick to incandescent bulbs. I am using a USB hub with a bright blue LED as my load. On a sunny day, the LED was much brighter than indoors, but not as full as when the hub is plugged into a USB port. Even in the sun my phone isn't getting charged. I am currently using two 3 volts cells but I own four. Do you think it would work if I used three or maybe all four cells? (My only worry is that the regulator will not be able to handle 9-12 volts and it might get fried.)

[SWV1787]

I don't know if the voltage regulator chip does it but I always thought you needed a diode to prevent power back flow from just killing your devices battery in low light.

[iPodGuy]

I was wondering about this as well. Could the author clarify, please?

Neat i'ble! I love solar gadgets!

[MattCP]

Yeah...you are absolutely correct. A diode would prevent any charge being dissipated back through the solar panel when there is not enough sunlight. (dark really). I thought of this charger being tossed in your backpack and pulled out to boost your phone or iPod on nice sunny days...
I don't think the reverse flow will damage the phone's battery...just drain it. (?) But to be on the safe side, a diode connected to the positive from the panels could be a safe bet. Isn't there a bit of a voltage drop tho? I'm working this stuff out as I go.
Cheers for the comments!

[solaralternatives]

The drop across a typical silicon diode is ~ .7v

[juanjomf]

Hi sorry my English.
I'm from Uruguay .. If you know that maximum solar cell gives 5 volts. not ever require anything.
I put my cell 5 volts directly with a 1N4007 diode or similar just for safety.
I saw that the solar cell without the diode calienta.Lo another bear in mind that we have 5 volts but the amps?. Minimo 100 or 150 milliamps need to show that the loading, the majority of small cells are only 80 milliamps, my advice is cell buy 8 or 12 volts and 150 milliamps or 200 or put 2 ceeldas of 5 volts and then put 5 volts regulator LM7805. Greetings ..

[armarares]

Quick question: can you fry the regulator if you hook it up wrong?(+instead of -)
I did that and now it does not output anything!!

[stephen jeorge]

i really really love the project!! can i have the circuit diagram?? please.. please.. please.... thank you... thank you... thank you...

[stephen jeorge]

i really love the idea.. and i like to create one.. how can i view the circuit diagram of that project? could you help me?? please.. thank you...

[mark56500]

Hey i love the idea and i just made one of my own, i tested it and i get 5v out of the usb port but when i plug in my phone it just lights up and does not say charging. Does this mean its not charging or i just dont have enough current for it to work? I'm using a 6V 100mA solar panel

[dtommyd]

Since there isn't a battery as a buffer doesn't it start and stop charging with every cloud? I have some of those I may need to try it out.

[rpvanpatt]

So, I have a panel that puts out about 8-9volts...I put a 5v regulator on it and a blocking diode, which brings it down to bout 5.5v in sunlight. I hook up the usb female port, then test it by plugging in a phone, and it will say charging for about 10 seconds but then cuts out....any ideas? I am going to hook up 4 chargeable batteries to it, so it will charge the batteries, then batteries will put out for the usb charger...think this will work better?

[tank1000]

I made one of those chrger to but i put mine into an old book i had abound my desk. i used i 6v 100ma solar panel. how many amps does the one you made put out?

[MattCP]

Awesome...mine is a at work, so I will hook it up and let you know the amperage.

[jcgeorgia]

When I check the usb with a meter, it gives out 2.5vdc and 6vac. Is it safe to say that I don't need the voltage regulator? I don't get anything on the meter when I have the voltage regulator soldered in. And I have paid close attention to keep from wiring it wrong.

[MattCP]

Might want to be certain of the max voltage output from your cells. I like the safety net of using the voltage regulator. The amount of photons hitting the solar cells has a direct relationship to the voltage output. Getting enough light?

[jcgeorgia]

after unsoldering the voltage regulator, i soldered the usb directly to the solar panels. I put it in the sun light and my meter reads almost 5vdc. I borrowed a digital meter and it reads .39mA. My guess is that the solar panels just arent generating enough power to charge anything. I tried my bluetooth earpiece and it didn't show it was charging. Oh and nobody in my house has an iphone. I did try it on a Droid X but that was before I pulled the voltage reg off.

[MattCP]

Yeah, there can be a huge difference in voltage output from the cells. Depends on the amount of light and the max output from your particular cells of course. The voltage regulator prevents it from exceeding 5v...safer for the device.

[jekan6861]

a warm hello from a cold Japan. Could you possibly tell me where I can source the cells in your picture. They look as though they have a resin of plastic cover? Many thanks
Je Kan

[MattCP]

I got these particular ones from http://www.technologysupplies.co.uk/ a few years ago and they have been in my spare parts drawer for a while.
You could try http://www.solarbotics.com/
I lived in Tokyo for a few years, Tokyu Hands dont carry solar cells? (It is the greatest shop on earth after all!)

[AMP678]

Tried it with an iphone? I've heard they're picky. and how many amps does it put out?