question

I had similar questions when I installed 4 100 watt panels on my RV. I ended up doing a bunch of tests including partial shading in both all parallel and all series configuration. For my system, all series had a slight edge with partial shading. It is amazing how little shade it takes to shut down a panel. And pretty much any shade cuts the output in half. The panels I have run two strings of cells in parallel so that probably explains the 1/2 output with any shade.

You will always be better off with more controllers. In any situation where a panel has reduced output and is combined with other panels before the controller, the array's output will be limited by the compromised panel. In a series configuration, the string's current will be limited to the compromised panel. In a parallel configuration a compromised panel probably has a reduced max power voltage so it's contribution essentially drops to zero.

If you have the money, I'd go for 2 panels to a controller. After installation, run tests to determine if you are better off with series or parallel.

To get the best low light performance having panels in series will generate the voltage necessary to wake up the controller. Least problems from shading will be obtained from a parallel configuration. For me it would be either option 5 or 7. Option 7 gives you best performance in shade from those two and also the best graceful degradation should a controller or panel go down.