DIY Solar Phone Charger ($5 Battery Free - UPDATED!)




About: Hi I'm Angelo! I am a college student taking my engineering majors in BS-EE/ BS-ECE at the DLSU. I use my course as an inspiration for making my current projects! I've been posting projects here ever since I...

Here's a real quick and easy tutorial on making a "Portable Solar Phone Charger", it only took me 5 minutes to make one! It's powered by PURE solar energy. The device is designed to fit right into your pocket, it also comes with a built-in stand! Works with apple devices (tested on iPod Touch and Quadcore Android Phone)

How Does It Work?
Solar powered chargers and powerbanks are pretty common these days. These devices usually have battery reservoirs inside them, to cut it short they are not 100% solar powered so as being eco-friendly. These products are gimmicks, they defeat the purpose of being 100% green and eco-friendly. My DIY tutorial will teach you how to make a "100% PURE Solar Phone Charger". Feel free to be independent from the power grid :D

My Review: (Pure Solar vs. Solar+Battery) 

  100% Pure Solar: (Pros)                           100% Pure Solar: (Cons)
   - 100% eco-friendly                                     - Can only charge devices during day
   - No need for charging internal bat.             - May Not Work with TABLETS (High Amp. Devices)
   - Independent From The Power Grid          - Ideal for outdoor use (where sunlight is present)
Solar Power Bank (w/battery): (Pros)            Solar Power Bank (w/battery): (Cons)
   - Can charge high power devices anywhere    - Conatains Lion Batteries (limited lifespan 1-2 years)
   - Doesn't need sunlight (internal battery)         - Not Completely Eco-friendly
                                                                             - Takes a long time to charge internal battery

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Step 1: Tools & Materials

The links below are just alternatives since the stores where I bought my parts where just available localy in the Philippines. When converted into PHP to USD the price of my spendings would become $5! It's real cheap. The solar panel only cost me $3.

Materials: (Click on the link to see where to buy)
- 6V Mini Solar Panel
- 5V Step-Up/ Inverter USB Charger Circuit ($3
- Your Smartphone (for testing)
- Your Phone's Charger Cable (Interchangable)
- Flexible and Foldable Plastic Card (for stand)

- Hot Glue Gun
- 30W Soldering Iron
- Leatherman Multitool

Step 2: Choosing Your Charger Module (UPDATED!)

Step 3:

The USB charger circuit came from a cheap old iPod USB charger. The main chip is similar to the well known MAXIM inverter chip. The circuit is a step-up/ step-down regulator, meaning when the power supply is underpowered it tends to boost the voltage but when the power supply is overpowered it limits the output voltage. It's ideal for solar powered purposes.

1st.) Dissemble a 12V High Power USB Charger.
2nd.) Cut the wires, short enough to be mounted on the solar panel.
3rd.) Solder the charger circuit to the solar panel (Adding a switch is optional).
4th.) Use a hot glue gun to mount the charger to the solar panel.
5th.) Be sure that the USB port is not protruding and the circuit should not touch any other leads on the panel.

Step 4: Adding the Foldable Stand (optional)

I recycled an old gaming prepaid card and bent it with a ruler. I also hot glued it to the right side of the solar panel.

Step 5: You're Done!

Now enjoy being completely independent from the power grid. I forgot to tell you that I have an interchangeable USB charger cable for Apple 30 pin, Micro USB, Mini USB, Samsung, Motorola, and Nokia, you can find one in your local dollar store. 

You can now carry your own personal solar powered charger anywhere. It's also a perfect survival kit since sunlight never runs out :)))) Have fun! :D

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83 Discussions


3 years ago

ACAS, please remove or fix this instructable before someone fries their phone.
I'm not sure why you thought to use a step UP USB circuit, but it really isn't a good idea.
Scenario 1, the phone takes charge.
Unless a 10W panel is used, the phone is likely to use all the current it can suck from the circuit, the solar voltage will be loaded down by the step up regulator, probably to between 1 and 2 volts. Solar cells are effectively constant current devices, so instead of putting out ~4V and say 200mA, it will only give 1 or 2 volts at 200mA. That's wasting 3/4 to 1/2 of the directly connected power.
Scenario 2, the phone isnt trying to charge.
This is potentially dangerous for your phone, with no load on the charger output, the voltage WILL RISE TO THE OPEN CIRCUIT SOLAR VOLTAGE. A step up regulator does not have circuitry capable of reducing voltage. I measured my $1 6V 1W panel at 7V yesterday, not enough to damage the old phone I was playing with, but it refused to charge until I shaded the cell to bring the voltage down. If someone used a 12v panel with your instructable, the phone could see over 20V! I'd only test that on a phone I was about to throw away...

To do this properly (and cheaper!):
6v panel
5.1V zener diode of at least the wattage of the solar panel.
USB charging cable. Cut off a charger or cut the supply end off a standard one.
The zener is connected ACROSS the panel, the striped end to positive.
The USB cable is red to panel positive, black to panel negative. If using a cable cut from a wall charger, you're probably done! If there are green and white wires in the cable, connect them together but to nothing else. Insulate them.

Test that in bright sun and not connected to a phone, the panel voltage is about 5.1V. Up to 5.5V is within USB specs.

If it all looks good, plug in to your phone and watch it charge! I use the 'Ampere' app to check charging current.

This is for androids. Apple stuff needs the green and white wires to have set voltages, a wall charger may have that circuitry in the phone plug end, though.

2 replies

Reply 3 years ago

Just have a question. I am working with my kids on a summer project to build one of these. Obviously I don't want to kill anyone's $400 phone in the process.

You state "USB charging cable. Cut-off a charger or cut off the supply end of one". I'm not clear on what you're referring to. Are you implying to just take a USB to Lightning cable and cut the USB end off? I have a USB extender that I would like to use so I can charge either and apple or android device. I assume that will work too.

Based on you comment, the whole USB 5V step-up piece is not required. Correct?


4 years ago on Introduction

I have built the circuit, but the percentage of mobile battery - during charging - less and less. I do not know why? Everything works, the step-up / inverter LED lights, indicating that the cell is being charged.

1 reply

Reply 8 months ago

If the phone is switched on, it could be using more power than it is getting from the tiny panel. I am assuming you don't get reverse current drain out of the phone and into the circuit.


Question 1 year ago on Step 2

Can you show me a picture of the type of charger you used to dissemble


2 years ago

A 6V solar panel gets around 300mA output in summer when the sun is
bright. Using a step up converter you may get a 5V constant dc current
but best case scenario the current will be converted to around
600-650mA. Meaning that this set up will not work as most modern
androids require at least >700mA to start charging


3 years ago

Wouldn't it be annoying if you're in a cae and the sun keeps blocking it? A capacitor is not big enough and battery makes things complicated!aybe i could use 4 bulky ones :D in parallel


3 years ago

Guys i am realy interested what you think about this its a device to wire youre phone for free.... you think this is possible???


3 years ago

Actually, Apples will probably charge at a max of 100mA or 500mA, so worth trying on small panels. I don't know anyone with an Apple to check this, though.


3 years ago

I have tried with a 6V 720mA solar pannel and a DC-DC Converter Step Up Boost Module 2-5V to 5V 500mA (the one of the first image on step 2) and the battery keeps going low.

I am a bit desesperated...What do you think the mistake could be?

Thank you all!!!

1 reply

Reply 3 years ago

Try 2-3A instead of 0.5. >2A is needed for a tablet.

Builders ShedAmalD4

Reply 3 years ago

You don't need a diode if you got the charging circuit from a car charger.. it already has a diode.. when you don't have a car charger just buy a 5v step up charging module and a 1N914 diode :D


3 years ago

I don't understand if the step up inverter/charging module is strictly necessary since I've read that all modern phones have a built in charging controller circuit and they are able to manage the ma/h and voltage. So is it true that I could connect a solar panel to the phone straight away? I just ordered a 5v, 4W module.