Obviously the solar panel. A 5W Solar panel available in most of the local electronic shop for less than ₹500, was enough for a decent charging. The size is ~ 30 X 20 cm. Almost a size of a laptop, but it is fine for me, after all, an experimental project for my own use. When kept in the morning sunshine, the output is nearly 4.4W(10V X 440mA).

Whatever the output that comes from the solar panel cannot be used to charge the mobile directly. There are 2 options that are available here,

Since a Buck converter is efficient with close to 90% efficiency, I chose Buck converter. I got this under ₹140. Also there is an adjustment available in this converter, which helps to adjust the output voltage to desired voltage.

My main intention was to have a mobile charger. So I used a USB female, which can be utilized by many other electronic equipments such camera, power bank, etc.

When you keep the female USB in a way, that the metal connectors faces up, out of 4 metal connectors, the right extreme of the USB is Vcc and the left extreme is GND. Where Vcc is expected to be 5V wrt GND.

Required wires and adapter-pair/Connectors. Utility equipment such as Multimeter and a Soldering gun.

Since everything was readily available, assembling them is the only actual work that I have done. I soldered all the components with adapters so that I can assemble or change any of the components when needed(modular).

And as I assembled all these, I am able to charge my mobile using a data-cable.

I am getting an output of 5V and 0.8A, which is 4W, from a solar panel delivering 4.4W. So I am getting almost 90% of efficiency.

Daily, I am able to harvest enough energy to charge my 3000mAh mobile battery.