DIY Solar USB Charger: 7 Steps (w/ Photos)

I recently made a DIY solar USB charger that, in my opinion, is WAY better than most of the other designs out there.

A solar charger being held in direct sunlight on a balcony

It’s portable. It looks good. And it can charge your phone and USB devices faster than the mere trickle put out by most other homemade solar chargers.

That’s right — it’s a DIY solar charger that you’ll actually use.

The best part?

It’s affordable and easy to make.

Here’s how to do it.

Materials & Tools

Materials

Materials for building a DIY solar USB charger laid out on a wooden table

Tools

Tools for building a DIY solar USB charger laid out on a wooden table

Step 1: Prep the Fabric

For this design, I upcycled an old reusable grocery bag to cut a strip of fabric to which I attached the panels. It protects them and allows them to fold up for easy storage.

Place the panels, eyelets (if using), and DC/DC buck converter on the reusable grocery bag in your desired layout.

Tip: I recommend giving yourself 1″ or more of space between your solar panels so they can fold easily. I also gave myself more length than necessary so I could fold the fabric over the buck converter, as you’ll see in Step 6.

Two 3W 9V solar panels and four eyelets laid on top of a reusable grocery bag

Cut the fabric to your desired dimensions with scissors. (Mine ended up being about 14″ long by 8.25″ wide.)

Two 3W 9V solar panels, four eyelets, and a USB buck converter laid on a strip of cut fabric

Step 2: Wire the Solar Panels in Parallel

Cut a length of wire to connect the panels’ positive terminals. Give yourself some slack in the wire so it isn’t pulled taut when the panels are folded.

Note: Because my panels have two pairs of terminals on back, before wiring I used a multimeter to check their voltages. It turned out the terminals that output 9 volts are the two “top” terminals — not the terminals with the “+” and “-” signs. Strange.

Two 3W 9V solar panels, a length of red wire, a roll of red wire, and wire strippers laid on a surface

Strip and solder the wire from positive terminal to positive terminal. (I decided to orient my panels in opposite directions to lessen the stress on the wire when the panels are folded.)

Tip: Keep your solder joints as flush as possible with your solar panels. This helps later on when gluing them to the fabric.

Two solar panels wired together with a red wire

Cut a length of wire to connect the panels’ negative terminals. Once again, give yourself some slack.

Two small solar panels, a length of black wire, a roll of black wire, and wire strippers laid out on a surface

Strip and solder the wire from negative terminal to negative terminal.

Two 9-volt solar panels wired together with red and black 22 AWG wire

Step 3: Solder the Leads to the Panels

Cut a length of wire for the panels’ positive lead. It will connect one of the panels’ positive terminal to the buck converter’s positive terminal. Make sure it can reach where you want to place the converter. Don’t forget some slack!

Two 3-watt solar panels wired together in parallel with a length of 22 gauge red wire on top

Strip and solder the positive lead to one of the panels’ positive terminal.

Two solar panels wired in parallel with a red lead

Cut a length of wire for the panels’ negative lead.

Two 333 mA solar panels wired in parallel with a red lead and a length of black 22 gauge wire resting on top

Strip and solder the negative lead to one of the panels’ negative terminal.

Two portable solar panels wired in parallel

Now let’s test the panels’ voltage and amperage outputs with a multimeter to make sure we wired everything correctly! Connect the meter’s positive probe to the positive lead and its negative probe to the negative lead.

What outputs should we expect?

Well, here are the specs for the panels I used:

  • 3W
  • 9V
  • 333mA

Wiring solar panels in parallel adds the current (amps) together while keeping the voltage (volts) the same.

Thus, for volts, you should see a number around 9V DC.

Testing the voltage of two solar panels wired in parallel with a digital multimeter

Almost 10V DC. Perfect!

For amps, you should see a number around 666mA (333mA * 2). But in real world conditions, expect solar panels to output a little less than their stated current.

Tip: You’ll likely have to switch the red probe to your multimeter’s other port in order to measure this amount of current.

Testing the amperage of two solar panels wired in parallel with a digital multimeter

557mA. Check!

Step 4: Solder the Buck Converter to the Leads

Locate the positive and negative terminals on the buck converter.

A hand holding a small 5V USB buck step-down converter

Solder the positive lead to the converter’s positive terminal and the negative lead to its negative terminal.

Two solar panels wired to a 5-volt USB buck converter

Now you should have a working solar charger!

Time to check that it’s working.

First, make sure the buck converter is connected properly and working by shining some light on the panels. Its LED should light up.

A USB buck converter with a small red LED light turned on

The LED is on. Looks like it’s working. ✅

Next, test your charger by placing it outside in direct sunlight and plugging in your phone or USB device. Your device should start charging.

A solar charger charging a Kindle

My Kindle’s charging light turns on when I plug it in — my charger is working!

I tested my charger’s output with a USB meter to confirm that the charger was indeed outputting a decent current at 5V.

A USB meter displaying the voltage and amperage output of the solar charger

It’s outputting 460mA (about half an amp) at 5V. That’s about 2.5W, or half the rate of a standard 5W phone charger. (During real-world use it regularly got up to 3W.)

According to our solar charging calculator, it will take about 10.8 hours of direct sunlight to fully charge my iPhone XR.

Definitely not the fastest solar charger, but it’ll top off my battery in a pinch.

Optional: Shrink wrap the buck converter using heat shrink tubing and a heat gun. I did this to for aesthetics and to protect the circuit board a bit. It covers up the converter’s LED, but that wasn’t a big deal to me.

A USB step down converter shrink wrapped in black heat shrink tubing

Step 5: Glue the Charger to the Fabric

Grab your glue and the strip of fabric you cut back in Step 1. Glue the panels and buck converter to the fabric in your desired layout.

Tip: The glue I used bled through the fabric a bit, so you may want to put a piece of newspaper down first.

Solar panels glued to a strip of fabric laid on top of a piece of newspaper

Wait for the glue to set. Once it has, touch up any spots you missed, if needed.

Step 6: Install the Eyelets (Optional)

Because I’ll be using my charger while hiking and biking, I wanted to install eyelets so I can strap it to my backpack and bike. If you don’t need to attach your charger to anything, you can skip this step.

First, let’s install the two eyelets at the “bottom” — the side opposite the buck converter.

Cut a circle in the fabric using the eyelet as a guide. Feed the eyelet bottom through the hole.

Tip: Since I used such small eyelets I just cut a small X with my scissors. You could also create a hole by poking a nail through.

An eyelet bottom poking through a hole in a strip of fabric

Place the eyelet base tool underneath the eyelet bottom. Place the eyelet top on top of the fabric.

An eyelet top and bottom ready to be installed

Place the eyelet punch tool over the eyelet top. Hammer the punch tool to install the eyelet.

An eyelet installed in a strip of fabric with eyelet tools nearby

Repeat these steps to install the second bottom eyelet.

A DIY solar phone charger with two eyelets at the bottom

Now it’s time for the top eyelets — the ones on the same side as the buck converter.

To protect the converter, I decided to fold the extra fabric over it and cut a hole for its USB port. (If you don’t want to do that, just install the top eyelets like you did the bottom ones.)

A USB port poking through a hole in a strip of fabric

Then I installed the top eyelets through both layers of fabric, glued the flaps together, and glued the USB port to the fabric.

Note: Don’t cover up any of the solar panel!

A completed DIY solar USB charger resting on a table

Wait for the glue to set, and you’re DONE!

Step 7: Test Your DIY Solar Charger

Now that you’ve made your own solar-powered charger, it’s time to charge something with it!

A DIY solar charger resting on a table on a balcony

Place it outside in direct sunlight. Plug in your phone or other USB device. Then sit back and relax as you take advantage of all that free solar energy.

A solar charger resting on a handrail in direct sunlight

When you’re done charging, fold the charger shut for easy storage.

A folded solar USB charger with the USB port showing

This charger doesn’t have a built-in battery. Adding a battery makes a homemade solar phone charger more complex.

You can easily pair your charger with your battery pack of choice (I use the Anker PowerCore II 10000). Charger your battery pack during the day, then use it to charge your phone or USB device at night.

Discover More DIY Solar Power Projects

1. DIY Solar Flameless Candle

Despite this candle’s circuit being more complex than the charger’s, it’s a great solar electronics project for beginners. It uses a simple solar light circuit that you can repurpose for many different DIY solar-powered lights.

More projects to come!

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Alex Beale
Alex Beale
Hi, I'm Alex. I started Footprint Hero to help people reduce their environmental impact. My current obsession is DIY solar power projects, which I've been building since 2020.
Alex Beale

Alex Beale

Hi, I'm Alex. I started Footprint Hero to help people reduce their environmental impact. My current obsession is DIY solar power projects, which I've been building since 2020.

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