The voltage system of the solar panel is divided into 12V and 24V, and solar panels of the same specification can be connected in series or in parallel.The electrical performance parameters of the modules such as, Isc, Voc and Pmax are nominally ±3% error under standard test conditions.
When the modules are connected in series, the final voltage is the sum of the individual modules, when the modules are connected in parallel, the final current is the sum of the individual modules.

 
Connecting in series

 
Connecting in parallel
Connecting in parallel after connected in series