Changes to calculation of horizon shading

[laurahin]

We typically compare results for a fixed set of projects before moving ahead with PVsyst software updates.  Looking at our last few comparisons, there is a big change in the horizon losses (in %) between versions 7.2.21 and 7.3.1 and then again between versions 7.3.2 and 7.4.1:

	PVsyst version
Project	7.2.21	7.3.1	7.3.2	7.4.1
1	1.23	0.94	0.92	1.27
2	0.26	0.22	0.22	0.28

The second change is likely due to the change in horizon treatment the was implemented in v. 7.3.3 ("Horizon (far shadings): the calculation of the horizon shading has been corrected for times the sun passes the horizon line. This may slightly change the simulation results."), however I can't find an entry for any change to the horizon calculation between 7.2.21 and 7.3.1.  Could you tell us what happened in that range that would've caused the horizon losses to change?  The values above suggest that the change in v. 7.3.3 just returned the algorithm to its previous form.

Thanks,

Laura