When choosing to have solar Panels you can either plug the 12 volt ends in to your 12 volt application and have it run while the sun is out or, direct the power in to a battery bank, for using at a later date.
There are 3 main ways to connect your batteries Series, Parallel, and Series+ Parallel
Connecting your batteries together in series, IE connect the + to the – and then the remaining open ends to your application/inverter. this will increase the voltage coming from the battery but keep the AMPs the same.
connect all the + and all the – up and connect these to your application or inverter. This will increase the AMPs and keep the voltage the same
Connect 2 sets of 2 batteries in parallel and then connect the + from one in to the – of another, connect the remaining – and + to your application. This will increase both AMPs and VOLTs.