Solar Freaks

Greetings,
I'm third year EE student trying to do MPPT with the help of DC-DC controller MAX1771. Specifications are:
Vmp of panel is 4.7 V
Voc=5.33V, Isc=455mA.
I need to charge a Li-ion battery of 4.2V,nominal capacity 1850 mAh. Loads are connected to battery through load protection circuitry.
I have connected a battery charger BQ24002 after MPPT which will control the charging discharging of battery safely. I've tested MAX1771(the converter) and it is working well, i.e for input 3 to 11 V it gives constant 5V output. Now the second step would be to give PWM to FB pin of MAX1771. Converter circuit's been attached. I've connected INA219 after MPPT which senses V, I and P. I've tried giving PWM through micro controller based on variation of output current of MPPT.


I'm a little confused about working of MPPT. My queries are-
1.Is panel current and voltage used to vary duty cycle of PWM? or output voltage/current of the converter? I want to know what is/should be the controlling parameter here.
2.How to test in lab if your MPPT is working and tracking maximum point? How to validate MPPT?

Thank you.