NOTE: no bug but clarification question.

Reading the tutorials is is unclear how inverter connections are defined and the power of a whole PV system of more than 1 string is calculated.

The notebook shows that 1 module is picked and then DC power calculated.
http://nbviewer.ipython.org/github/pvlib/pvlib-python/blob/master/docs/tutorials/tmy_to_power.ipynb#DC-power-using-SAPM

But the next step
http://nbviewer.ipython.org/github/pvlib/pvlib-python/blob/master/docs/tutorials/tmy_to_power.ipynb#AC-power-using-SAPM

uses a micro-inverter on module level.

How would the whole process be done with a different inverter, say a 30kW multi-string inverter?

And how would these then be added into a system of 500kW?

If it's roof-top, then multiplying by number of inverters would be possible but on a flat roof or ground mounted case, row-to-row spacing would need to be accounted for.