Hi Jestin
No you can't because for a solar panel when your required current is going to be higher , then out put voltage of the solar panel will be decreased . so you can't change it with that . but you can use a simple way to charge a battery like that with a solar panel like that ! but it will take a bit longer time .
is there any reliable circuit for 300W DC link inverter ?
A PV panel rated for a 12 V system, puts out sufficient voltage to charge a 12V battery up to 16 V or so. With no load the panel puts out 16V to 22V.
Your panel has sufficient output to charge your battery at a C/5 rate. (I was not sure whether to take your 100W figure or the 50W. I'm going with 100W.)
I suggest you try connecting the panel directly to your battery, and measuring the current.
Do this on a bright clear sunny day, to find out the maximum amount. Watch how fast the battery volt level goes up.
Tests like this will let you know what sort of charging pattern is appropriate for your system.