With modules of CIS / CIGS technology, we usually observe an increase of the performance after several hundreds hours of exposition to the sun, due to an atomic rearrangement in the cell's material structure under light effect.

This is claimed by some manufacturers to be of the order of 3 to 5% of the initial STC values, but this is usually not reported in the specifications. You can specify this gain (according to manufacturer's advices), but you should be aware that the resulting simulation  will not be valid for the first production year.

And we don't have any information (at the moment) about the real duration of this benefit.