[DamonHD]

IMHO "efficient" isn't really the right term in your second para. The PV generation per W incoming is actually a little lower at higher ambient temperatures, but is otherwise fairly constant.

I assume that you mean higher kWh/y/kWp, ie you get more generation out of a given solar panel in the south each year.

[pfdietz]

"Effective" might be the better word.

It's unfortunate that "efficiency" has both engineering and economic definitions.

[wrsh07]

I meant kw h/m^2/d I think, but I'm not sure what the simplest way to say that is

I think you and I are saying the same thing though!