Preliminary design for Grid-connected PV system

[Andel]

Hi PVsyst team,

I am doing preliminary design for large-scale solar parks with total available area of 80 hectares. I have estimated the GCR of 50% and pitch of 10m and then the results showed that the nominal power is 84000 KWp.  

After that with same total area and with same GCR I have just changed the pitch to 8m but I got same results 84000 KWp !!

How that can happen for same area with different pitch values I get same results for the total nominal power? 

Are there some assumptions in PVsyst for calculating the total nominal power and why the the results didn't change ??