Hello Niksk,
As far as i can tell there are three ways this can work.
1) You use the existing PV panels in ecoinvent, or use production data for pv's you have from suppliers
2) You find published literature of the impacts, and add these impacts as results in OpenLCA.
3) You can find published literature , and add it out of software, e.g. in an excel sheet, after exporting your results from OpenLCA.
Hope this helps, good luck