The Solar USB Charger!




About: I love making things and simple electronics!

Have you ever been camping or driving and your phone runs out of battery?  These moments are very frustrating, and they led me to make my own solar phone charger.  Most retail solar chargers cost $40-$50, but by following this instructable, you can make your own for around $20!  Another great thing about this instructable is that is requires no soldering, so it is great for students or kids.  If for some reason something happens to your phone while charging with this device, I am not responsible.  Have fun!

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Step 1: Materials

You will need...

* A 9v 0.5 Watt Solar panel (Radioshack)
* A DPDT mini toggle switch (Radioshack)
* A USB extension cable- Male to Female (Dollar Store)
* 4 rechargeable AAA batteries (already had mine)
* 4 AAA battery holder
* Thin stranded wire
* Electric Tape
* A relatively small project enclosure (Radioshack)
* Optional- Labels
* A standard blocking diode

* Drill with drill bits
* Hot glue gun with glue
* Wire stripper

Step 2: Step 1:

Step 1: Drill two holes on the lid of your project enclosure 2cm apart so the wires on your solar panel can enter the box.  Make sure the wires fit.  I made sure that my solar panel was all the way to one side of the enclosure so there was room for the switch to be installed.

Step 2: Drill a hole large enough for the top of your toggle switch to fit through on the opposite side of the solar panel.

Step 3: Step 3:

Step 3: Fit your switch into the hole you drilled and hot glue it in place.

Step 4: Drill a hole in the side of the box as shown in the picture.  This will be for your USB cable.

Step 4: Step 5:

Step 5: Put the solar panels wires through the holes you drilled, and hot glue the panel in place.  Attatch the blocking diode on the positive wire so electricity cant flow back into the solar panel.  This is extremely important, because the panel can be damaged if this is not done properly.  I found it easiest to not worry about that side's screws because the lid stays on fine without them, so feel free to put the panel on thop of them.

Step 6: Cut your USB extension cable in half, and save the Male side of the USB for other projects.  Strip the Female side of the USB's  wires, revealing  black, white, gray, and green wires.

Step 5: Step 7:

Step 7: Twist together the white and green (data) wires, and put electric tapearound your connection.  This connection makes your phone understand that this is a charger.

Step 8: Feed the USB Cable through the hole in the side of the enclosure and hot glue it in place.  Make sure you leave some slack so if you mess up, you still have some wire to work with.

Step 6: Step 9:

Step 9: Attatch the wires to your switch as shown in the diagram.  Make sure you keep positives on the same side as positives and negatives on the same side as negatives. 

Step 7: Step 10:

Step 10: Hot Glue all of the wires onto the switch.  Put the lid on your project enclosure, switch the toggle switch so it is charging the AAAs, and let the solar panel charge up the batteries. 

Step 11: (optional) Put labels for "input" and "output" on either side of the switch so you know which side is which.

Step 8: Enjoy!

Plug your phone or USB cable into the Female USB cable, switch the toggle switch to "output", and let your phone charge.  Now you will never have to worry about getting stuck in the car with a dead phone, or even at the beach or a camping trip!  Enjoy!

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    19 Discussions


    4 years ago on Introduction

    Important remarks about the charging IPods and Iphones, all the Iphones from IPhone 4s Going up require a data signal from the USB port to charge, thus the above circuit won't do it for you, am searching for a way to hack that in the meantime, one obvious way is to connect resistors to the data pins but i still didn't figure out the appropriate rating for them.

    Phil B

    7 years ago on Introduction

    A 1/2 watt solar panel producing 9 volts would have a current flow of 55 milliamps. A typical USB port would produce nine times as much current. Would I be wrong in assuming a charging cycle would take quite a few hours to complete?

    3 replies
    mraywPhil B

    Reply 7 years ago on Introduction

    The AAA batteries would take a while to charge up, but that doesn't relate directly to the time that the USB device would take to charge from the batteries. Poking around, it looks like Ni-Cd AAA batteries can output much more current than a standard USB (although I could be wrong, as I'm having difficulty finding a reliable source).

    Basically, it looks like you'd have to leave the charger in the sun for quite a few hours to charge it sufficiently, but once fully charged, the charger wouldn't take all that long to charge up a phone.

    DoctorDvPhil B

    Reply 7 years ago on Introduction

    Correct, but I am looking to make an emergency charger for camping. Thanks!


    7 years ago on Step 8

    Is that actually charging your iPod Touch?

    I know for a fact a simple little power source on the power lines of the USB connector are not enough to enable charging of an iPod Touch. Most of Apple's Phones, iPods and iPads need a signal on the data lines of the USB connector to enable charging. This would be fine for some more basic USB devices but not for many smartphones.

    5 replies

    Reply 7 years ago on Step 8

    I am aware of that. The charging symbol did show up, but it didn't charge. It works with my phone though. do you have any tips to make this work with my ipod?



    Reply 5 years ago on Introduction

    The reason why it didn't charge is because the solar panel is discharging the battery from the lack of a blocking diode which prevents the flow of the electric current from going the wrong way.


    Reply 7 years ago on Introduction

    ladyada has done lots of research on this for her Mintyboost kits. I believe most of it is up on either her own website or


    Reply 7 years ago on Step 8

    When you plugged it in the screen turns on but the little lightning bolt doesn't show up in the battery indicator at the top of the screen.

    If you look up the pin-out for the 30 pin connector the iPods use you will find the info there. I'm reluctant to give you the info directly since its part of the instructable i've been working on for the past several days. I'll be entering it into the kit challenge when its done. I'm just waiting for my parts to arrive.

    Just look through the list of other solar phone chargers listed to the right here and see what they did.

    i can't find the AAA battery holder what can i do , any tips and where to fit the black and gray wire and i don't have the gray and green wire in the USB cable but red and yellow wire black and red are thick wire but yellow and white are thin,what can i do any tips for this problem please help


    6 years ago on Introduction

    This works on my wife's HTC one x, but not my Motorola atrix hd... any suggestions?


    7 years ago on Introduction

    I live in phoenix... I will never have to worry about power ever again.

    Oh, but can I solder it anyway?

    Another option would be to use two or three AAs and a boosting circuit in order to boost it up to 5V. Then you could use a lower voltage solar cell to charge your batteries. Plus then you could get a low voltage high amperage solar cell for quicker charging.

    Also, 4 AAAs would give you 4.8V. USB is 5.0 - 5.2V. Not everything would charge off of it.

    It's a swell idea, but you could easily add a couple of tweaks to make it much more efficient and hold a whole lot more energy.

    Shoot me a PM if you'd like to talk more about it.