Inverter minimum input voltages and string sizes

I am wondering about the minimum input voltage needed to turn on an inverter. For example the Sunny Boy 6000TL-US-22 has a minimum voltage input of 360v initial and 300v minimum. My understanding is that the inverter won't turn on until it senses 360vdc and will turn off if the voltage thereafter drops below 300vdc. When I run Sunny Design Web it configures 21 Yingli 290 watt panels to a 6000 Sunny Boy inverter into 2 strings, one string of 11 panels (string A) and the other of 10 panels (string B). This results in a "typical PV voltage" of 372vdc for string A and 338vdc for string B. The 372 volts is fairly close to the minimum initial startup voltage and 338 volts is below this threshold. On the hottest day string A is expected to only put out 339 volts. Neither of the strings alone would put out the number of volts required to wake up the inverter. My question is simply whether the voltages from each string add in order to meet the minimum voltages? Does the inverter treat the strings in parallel or series? If the voltages don't add wouldn't it be better to configure the strings unequally, such as 12 and 9? Under this scenario string A puts out 370 volts even under when the panels are at their maximum temperature. This would wake up the inverter and it would then invert both string A and string B at 278 volts.