**Creating a DIY 5V Portable Solar Charger: A Step-by-Step Guide**
As we dive into the world of DIY solar chargers, it's essential to address a critical aspect - voltage regulation. Since the voltage can fluctuate depending on sunlight conditions and potentially damage components, we need a reliable regulator that outputs a constant 5 volts. I opted for a cheap bug boost converter as my first test subject.
To begin, I hooked up the bug boost converter to my lap bench power supply set to 8 volts and adjusted its output voltage to 5 volts. Next, I soldered a chopped-up micro USB cable to its outputs and plugged it into my phone, which successfully charged with a current raw of around 1.4 amps.
The awesome thing about such a bug boost converter is that the input voltage can vary below or above the desired output voltage without affecting it. This flexibility will come in handy when combining the converter with multiple solar cells.
**Protecting Solar Cells from Mechanical Stress**
In my DIY solar panel video, I used epoxy resin to encapsulate the solar cells, but this approach didn't quite work out as planned. The problem was that the metal frame was too large and held too many cells inside, compromising their mechanical stability. To resolve this issue, I designed a small frame for each cell and will encapsulate it in there.
Using Fusion 360, I created a design for the small frames, which were then 3D printed using my two Prusa printers and some red and blue PLA filaments. As soon as all the frames were done, I obtained a two-component transparent epoxy resin to test out this new approach.
**Assembling the DIY Solar Cells**
To assemble the solar cells, I mixed up a small batch of epoxy resin through the help of a stirrer and popped any air bubbles using hot air. Next, I poured some resin into each frame, distributed it evenly, placed a solar cell on top of spacers (with tapping wire already added), and finally topped it off with more resin.
After allowing the resin to dry for a sufficient amount of time, I was pleased to see that the finished cells were mechanically pretty strong. Electrical measurements revealed only slightly altered voltage and current values in sunlight conditions.
**Soldering Tapping Wires and Encapsulating Cells**
My next task was to solder tapping wires to nine more cells and encapsulate them inside 3D printed frames, just like I described before. The plan was to lay two cells on top of each other, shorten the tapping wire, and solder them together at the end of the two wires. This process needed to be repeated with constant alternations in cell orientation to allow for easy disassembly later.
Once all serious connections were made, rubber bands were used to keep the folded-up system together.
**Adding a Bug Boost Converter**
As soon as all cells were encapsulated and their tapping wires connected, it was time to add the bug boost converter to the outputs. This marked the final step before truly testing my DIY 5V portable solar charger in my garden.
**Testing the DIY Solar Charger**
In direct sunlight, I hooked up my phone to the solar charger, which successfully charged with a current of around 1.35 amps. When tested on a cloudy day, it still managed to charge at 0.7 amps.
To measure the maximum power output, I hooked up the system directly to constant loads and performed some tests. The results showed that my DIY setup could reach a maximum power of 26 watts.
Considering the cost of this DIY project was similar to commercial versions, while also requiring time and effort, I'm convinced that DIY is the winner in this case.