SMPS Solar Voltage Regulator Circuit Suggestion

[ric96]

I have a 30W 12v solar panel which i would be using to charge a 12v 7.2Ah Battery.
I require a SMPS 12v-20v to 5v regulator to charge phones from that battery or the panel. The output can be any where between 1A to 2.1A.
I have tried using things like the (in)famous L7805 but its not at all efficient
Can someone suggest me something simple to construct?

Thank You!

*My skill level, Can Make Simple Circuits If Well Labeled and Described*

[mikerj]

Why not just buy a car phone charger?  They all have switch mode regulators, are pretty efficient, are cheap, apply the correct voltages to the USB data lines and even come with the correct connector for your phone.

[ric96]

Why not just buy a car phone charger?  They all have switch mode regulators, are pretty efficient, are cheap, apply the correct voltages to the USB data lines and even come with the correct connector for your phone.

Because i am keen on making on my own ... Its been almost 4 yrs since i haven't done any circuitry at all...!