Why you want to use series (high volt) though? If your panel is far away and need to run a long wire. Why? Because the higher the volt like in series the thinner the required copper wire. Copper is expensive, you don't want to buy thick copper wires.
Correct the higher amps the thicker the wire needs to be. And the more loss you will have. BUT with a pwm charge controllers they don't covert the high voltage to amps so a parallel connection is better.
If you have solar panels far away and you want to avoid losing electricity, it is good if you connect solar panels close to the charging station, ok more cable will be used.
