Had some solar cell's from old solar LED garden lamps, and decided to build a solar battery charger panel.
Step 1: Gather Your Components and Test the Cells
Solar cells, Solder machine, solder, Wire and a Multimeter.
optional: Diode, heat shrink tube and a Hot glue gun.
Test the cells with a Multimeter and mark the + and - for each. Measure their size and create a 3D file for your frame.
Step 2: Design and 3D Print Your Frame.
I've design a simple frame with adjustable angle.
Feel free to use this one, the cells I used measure around 40mm by 48mm.
Step 3: Connect the Cells and Assemble the Frame.
Arrange the cells and lock them in place with the tip of the soldering iron (melting a bit of the frame on to the edge of the cells) or some hot glue.
In my case each cells measure a voltage between 2.9V and 3.3 V, connecting all four cells in series I got around 12V. You also can connect them in parallel and get more Amperage. Didn't tried that, but you can find better info in another Instructables about solar panels and how to connect them.
Start soldering!! some of the cells had a kind of epoxy resin protecting the solder joints, so you have to be persistent with the solder iron. Measure the voltage in each connection and seal them with hot glue.
At the end you can add a diode just to keep the current flowing in one way.