Am I understanding this correctly?

[Dave S]

Let's say I have 4 solar panels. I run two in parallel to produce 20 Vmp and 10 amps, and I run that to a positive and a negative buss bar. Then I take the other two and run in parallel to produce 20 Vmp and 10 amps and run that to the same buss bars. Do I now have 40 Vmp and 20 amps at the buss bars? Thank you.

 

[MisterSandals]

Do I now have 40 Vmp and 20 amps at the buss bars?

No, combining in parallel adds the amps only.
Putting panels in series adds the volts.

If you are looking for more volts, put 2 panels in series, then connect to bus bar.
To connect in series, take the + of one panel and connect to the - of the other panel. This sums the volts, leaves amps the same.

But if you want to create 2S2P array with 2x the volts of a single panel and 2x the amps of a single panel, just connect the series pairs with a simple Y connector pair, its a lot easier than a bus bar.

https://www.amazon.com/BougeRV-Connectors-Branch-Parallel-Adapter/dp/B0753X68PS/