PVSyst optimization tool differs from single shot simulation

[Emi]

Hallo everybody,

I tried to carry out an analysis with "Adavnced simulation/optization tool" for a certain range of tilt and azimuth in order to find the best orientation for a free standing plant.

obtaining a suspect results.

 

Optimization tools returns better performance for

tilt 9.7°

azimuth 30°

Egrid  1301 MWh

set-up azimuth from -30 to 30 , steps 30

set-up tilt  5 to 20 , steps 30

 

Then I tried a single shot simulation using tilt and azimuth I think is best choice.

Better, for single shot simulation I defined tilt and azimuth with same values shown in calculated series of optimization tool.

The result is very weird:

tilt 14.8°

azimuth 1.0°

Optimization tool returns   Egrid 1202 MWh

Single shot simul. returns  Egrid 1330 MWh

 

Any hints?

Many thanks