Variable on charging rate depending on weather and sun.
3 panels are going to be used.
5,000maH
Sounds a little strange, are you looking at the 12V 5Ahr Li packs?
The type of battery makes a pretty big difference for charging rate and max voltage.
Can you let us know what type of battery you'll be using.?
WE can then make sure the battery gets fully charged without cooked 8Amps is a lot.