**6. Conclusions**

In this study, a PV-string with a nominal power level of 1800 W was chosen as a case study for the evaluation of two PV-inverters based on the 2L QZSI full-SiC solution and the 3L NPC QZSI solution with Si MOSFETs. However, both investigated topologies could be easily up-scaled (with appropriately selected passive components) and safely operated up to twice the higher power level. The main conclusion from our analysis is that the full-SiC 2L QZSI solution has a clear advantage over the 3l NPC QZSI solution with Si MOSFETs. First of all, it simplifies the Printed Circuit Board (PCB) and reduces the number of auxiliary components around switches. Secondly, it may provide higher efficiency along with the lower volume of heatsink. It should be mentioned that efficiency and

heatsink volume can be used as trade-off parameters for industrial optimization. The heatsink volume increase will lead to the temperature decreasing and to efficiency improvements correspondingly. On the other hand, the reliability and longtime operation of the full-SiC solution is an open question for discussion and can be a limiting factor in industrial implementation.

**Author Contributions:** Conceptualization, S.S. and O.H.; methodology, S.S. and C.R.-C.; software, O.H. and S.S.; validation, S.S. and S.P.P.; formal analysis, S.S. and C.R.-C.; investigation, S.S. and E.S.; resources, D.V., O.H. and S.S.; data curation, S.S. and O.H.; writing—original draft preparation, S.S.; writing—review and editing, S.S., O.H. and D.V.; visualization, S.S.; supervision, D.V. and O.H.; project administration, O.H. and S.S.; funding acquisition, S.S.

**Funding:** This research was carried out with the support of the European Regional Development Fund and the programme Mobilitas Pluss under the project MOBJD126 awarded by the Estonian Research Council. This work was also supported by the Estonian Centre of Excellence in Zero Energy and Resource Efficient Smart Buildings and Districts (ZEBE), gran<sup>t</sup> 2014-2020.4.01.15-0016 funded by the European Regional Development Fund, and by the Estonian Research Council gran<sup>t</sup> PUT1443.

**Conflicts of Interest:** The authors declare no conflict of interest.
