The complexities of high PV penetration in the electricity grid in Slovenia based on targets proposed in national energy and climate plan were explored. Scenarios modeled an increase in installation power from 1800 MW in 2030 to 8000 MW in 2050. They were analyzed using energy modeling and life cycle assessment to assess the technical and environmental aspects of high PV grid penetration. The results showed that the increase in PV production from 2200 GWh (2030) to 11,090 GWh (2050) showed an unfavorable course of excess electricity in the system, resulting in the need for short-term and long-term storage strategies and exports of electricity. LCA analysis showed that penetration of a high share of PV results in a decrease in the impact category of global warming, which is higher in 2050 green scenarios that phase out coal and lignite electricity sources (80.5% decrease) compared to the 2020 baseline scenario. The increase in mineral resource scarcity can be observed with an increase in PV share when comparing the 2030 (50%) and 2050 (150%) BAU scenarios with the baseline scenario (2020). Factors such as environmental impacts, technical challenges, and the impact on the grid must be considered when implementing a decarbonization strategy.