Mppt voltage range vs max DC input voltage

[Sterling9250]

what’s the difference between max MPPT voltage range and max DC input voltage?

My inverter max dc input is 600V and the max range goes up to 550V. I’m wanting to use 14 panels that have a 45.16 open circuit voltage using Nominal Operation Cell Temperature (49.37 open circuit voltage using standard test conditions). Basic math puts me at a peak of 632 volts, which is obviously over either limits. 12 panels would put me at 541 volts. Should I keep it at 12 or can I push it to 13?

 

[BentleyJ]

12 x 49.4V (25C) = 592.8V The issue will be cooler temperatures causes Voc to go up. What is the coldest temperature you will experience at your geographic location. It may be necessary to reduce the panel count to 11.

Take a look at the data sheet and find Vmp or Vnmot. This is a better representation of the operating voltage when current is flowing.

 

[Sterling9250]

12 x 49.4V (25C) = 592.8V The issue will be cooler temperatures causes Voc to go up. What is the coldest temperature you will experience at your geographic location. It may be necessary to reduce the panel count to 11.

Take a look at the data sheet and find Vmp or Vnmot. This is a better representation of the operating voltage when current is flowing.

Coldest is about 0° C. I see a vmpp (rated voltage) of 41.60V (standard testing) and 38.05V (nominal operation).

 

[BentleyJ]

For simplicity lets say the Vmpp is 40V under normal operating conditions.

40V x 11 Panels = 440V which should be well within the MPP range of the charge controller.

49.4Voc x 11 Panels = 543.4V (at 25C)

At 0C, Voc will go up to 584.1V which is still below the 600V max limit. (calculation based on estimated temp coefficient of -0.3%/deg C)

11 panels per string is a much more conservative way to design the system.

 

[timselectric]

Coldest is about 0° C.

Look up the record coldest for your area.
This is not something that you want to guess about.