Wow Almot, I didn't realize westend, or BFL or even I was in those areas, yet in each case a 230w panel and MPPT has been more than enough. I didn't have a big inverter but I know the other two use more power than we did.
I have seen two 150w panels in series pushing the 20a limit of the Eco-w, but that was on MPPT too. Run those in parallel and you instantly lose the usable voltage from 22v down to the 13.6v the panel is rated at. Lost, gone, wasted. It is even worse when early on your battery is low and you lose even more because you can only use a portion of the watts available until the voltage of the battery is up to the voltage the panel is rated at. That's when a 160w panel is good for its rating. MPPT gives you the full potential of the panel no matter what voltage the battery is at.
Here is a page that puts it into laymans terms for those of us without a degree, and maybe some of those with one too. ;)
Click here