DIY Solar Phone Charger




About: "Making Renewable Do-Able" since 1999, altE specializes in selling off-grid, grid-tie solar power systems for the DIY'er. Friendly and knowledgeable staff will guide you designing and buying your solar panel...

We were looking for a simple, inexpensive, but efficient way to keep our cell phone charged when outside. Whether you are using your GPS while camping, playing music while tailgating, or out hunting Pokemon (watch our video), your phone may be burning through it's battery. By plugging its car charger straight into a solar panel, you can easily keep the party going.

We didn't want to complicate the system or make it expensive by adding batteries, so this will only work when the solar panel is in the sunlight. Likewise, we didn't want to make the system so small it couldn't keep up with your power use, so we used a 10 Watt (W) 12 volt (V) solar panel. Smaller solar panels are available, but they may not output enough current to charge your battery.

By connecting a cigarette socket to the solar panel, you can easily use your existing car charger to send the correct 5V to charge the phone. A 10W solar panel can output up to 2 amps at 5V, that's plenty to keep you going all day long.

Parts list:

12V 10W solar panel - $39

Cigarette outlet - $3

18AWG wire - 2 wires - $0.54/ft (5' used)


Step 1: Connect Wire to Solar Panel

If your solar panel does not already have wire attached, you need to open the junction box (j-box) and connect 2 wires to the back. It should be labeled as + (plus) and - (minus). Generally red is used for + and black for -. The solar panel may have a way to crimp or solder right onto the terminals, or you may need to crimp lugs onto your wire to screw down.

Step 2: Wire the Cigarette Socket

Most cigarette sockets that I have used have a flat terminal to slide on a spade female disconnect. Crimp a disconnect on each wire. If the disconnect does not have insulation on it, we recommend you use heat shrink to prevent accidental shorting of the wires.

The middle terminal is the positive (+), connect the red wire to it. The outside terminal is the negative (-), connect the black wire to it.

Step 3: Test the Socket

Bring your solar panel outside in the sun. With your volt meter, measure the output of the socket. Put the red probe inside to the metal circle on the bottom, and put the black probe on the outer metal ring.

If you measure a negative number, like -20V, the system is wired backwards. Figure out if you wired it wrong on the solar panel or on the socket. If you measure a positive number, like 20V, you are done!

Step 4: Go Outside and Play.

You just need to plug your car charger into the socket, and your phone will start to charge. If you want to make it a bit more portable, you can attach it to a backpack or messenger bag to wear around.



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    5 Discussions


    2 years ago

    Is it possible to charge multiple devices from this one panel? I am not too well versed in circuits, but wouldn't 12V be able to provide power to 2 devices (i.e. phones) at 5V and approximately 1.8A each?


    2 years ago

    So, putting 20v into a car charger rated to input 12v is safe and effective? Has this melted down yet?


    2 years ago

    Perfect for the camping trip!


    2 years ago

    Cool project! I see you kept it simple. Has that made the charger reliable/effective? I've been wanting to do a very similar project, though my inner mad scientist insists on adding batteries, indicator lights, usb plugs, etc . . . How you attempted any of those things? If so, have they affected reliability/effectiveness? (I live in Texas, so plenty of sun, but commercial solar chargers have not been very reliable for me, which is why I was considering a similar project when I saw this)

    1 reply
    altE StoreAngelD37

    Reply 2 years ago

    I'm glad you asked. We also made a bigger one with a charge controller and battery, with an optional inverter for AC. Check it out here,