That rating is the maximum rating allowed that will offer protection to the panel should something go wrong and current from somewhere else be able to flow back into the panel.
In parallel the only limits are, the gauges of wire and isolation switch ratings that you need to run to handle the current and your chargers input current limit. If more than 2 panels in parallel each panel should have a fuse no more than the rating on the back of the panel.
In series you have to contend with the voltage. Most domestic panels have a maximum string voltage of 1000V (eurospec) / 600V (UL spec?) but it is effectively the same rating. If you go over 1000V (there is a safety margin built in here) you can get electrical breakdown and then fires start. Of course you also need to keep the voltage acceptable to your charge controller / inverter. Most off-grid systems top out around 150VDC, grid tied usually around 500VDC but you can get 800VDC+ models. High voltage DC is not something to play with so avoid that if at all possible and play with < 150V systems.
Parallel or series, the voltages out of the array need to be within the usable range for your system. For systems with DC coupled batteries this typical means a fair margin over battery voltage. If you post your model inverter / charge controller that'll let people see the specs for it and give you some advice on how you can arrange your panels.
