Electrical equipment is rated by how much electricity they use, make, or store. For example, a 100W solar panel can make (under standard test conditions, STC) 18 volts (V) and 5.5 amps (A). A 1200Wh battery is rated by both the 12V and 100Ah capacity. When wiring components together, the way they are wired will change the way the ratings are affected.
Schematic for Wiring Solar Panels in Series
Wiring solar panels in series (plus to minus) will increase the volts, but leave the amps the same. For example, wiring two 18V solar panels together as shown will increase the output from 18V to 36V, but the current will stay at 5.5A.
Schematic for Wiring Solar Batteries in Series
Likewise with batteries, wiring two 12V batteries in series will increase the voltage from 12V to 24V, but leave the amp hours at 100Ah.
Schematic for Wiring Solar Panels in Parallel
Wiring solar panels in parallel (pluses together and minuses together) will increase the current, but leave the volts the same. So two 18V 5.5A solar panels wired in parallel will be 18V, 11A output.
Schematic for Wiring Solar Batteries in Parallel
Finally, wiring batteries in parallel will increase the amp hours, but leave the volts the same. So two 12V 100Ah batteries will be 12V 200Ah.