When using a charge controller do amps increase?

[Jeff]

Hello,
I'm new to solar power systems and have a question.
 
Using the MrSolar brand BSP-20-12 panel as an example.

The specs are 20 Watt Solar Module, 17.3 Vmp, 1.2 Imp

When using a charge controller to convert the 17.3 Volts max power to 12 volts DC, does the amperage output increase?
 
I make this assumption because of the relationship between watts and volts.
 
Watts/Volts = Amps
 
Using the BSP-20-12 Vmp voltage I calculate
20 watts/17.3 volts = 1.2 amps (which is equal to the stated Imp current for the panel)
 
Using a charge controller to convert to 12 volts I calculate
20 watts/12 volts = 1.7 amps
 
Is this a valid assumption, or not?

Why do I ask? Because I trying to convert to (theoretical) amp hours to see if I have the proper size panel to re-charge a battery after a defined amp-hour draw.
 
Thank you very much for your assistance.
 
Jeff