**5. Conclusions**

BIPV modules are installed during, not after, the construction phase and have a profound impact on the electrical installation and construction planning of a building. In this paper, system criteria were established for the electrical installations of building-integrated photovoltaics. These criteria serve as key performance indicators. Apart from energy-yield, factors such as engineering effort, availability, and modularity must also be considered when designing the installation as they impact project installation costs. Currently available electrical installation architectures, such as string inverters, micro-inverters, and series and parallel power optimizers, were compared according to the aforementioned criteria, favoring parallel module-level converters connected to a low-voltage DC grid for BIPV applications. LVDC grids allow a further reduction of the costs and an increase in the power density and lifetime compared to traditional AC grids. This is mainly because of the lower amount of conversion stages, leading to a lower amount of components. Although, the use of string inverters is mostly reported for BIPV. The requirements for BIPV module-level converters mainly differ from regular PV converters in terms of compactness, input range, and operating temperature range. Several methods were discussed that allow an improvement of these aspects for future BIPV converter designs. Furthermore, BIPV module-level converters must incorporate fault-tolerance techniques to meet the building element's lifetime requirements. Due to the difficulties in replacing the converter when it is embedded inside the framework of the BIPV module, it is of utmost importance that the converter is designed to fail safe such that a converter failure does not result in a system failure. Fault conditions in BIPV module-level converters were considered for different grounding configurations. Compared to the current trend of going to non-isolated PV converters, we recommend the use of transformer-isolated topologies which increase the fault tolerance of the installation as a whole. The preferred grounding configuration is TN-S, as it allows for simple fault discrimination based on the current intensity.

**Author Contributions:** Conceptualization, S.R.; resources, J.D.; supervision, J.D.; validation, M.D.V. and G.V.d.B.; writing—original draft, S.R.; writing—review and editing, M.D.V., G.V.d.B., and J.D.

**Funding:** This project received the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship, and the Province of Limburg. G. Van den Broeck, funded by a PhD gran<sup>t</sup> of the Research Foundation Flanders (FWO).

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