Parallel wiring increases amperage and voltage stays the same. Each cell in a parallel circuit is wired positive to positive and negative to negative.
Series wiring (mostly what you will use for solar cells} increases voltage and amperage stay the same. Each cell in a series circuit is wired positive to negative, the remaining positive and negative are you leads. You’ll notice batteries in flashlights installed in series.
check out this manual:
https://tocatchthesun.com/ its really good.
Thanks a lot !