Earth Fault Analysis and Safety Recommendations for BIPV Module-Level Converters in Low-voltage DC Microgrids

The strive to increase the penetration of renewables in urban areas has attracted the use of fac¸ade Building Integrated Photovoltaics (BIPV). From a system efficiency and cost perspective, an LVDC microgrid is preferred over a traditional AC grid to interconnect the BIPV modules inside the building. To address the problem of partial shading and further reduce the engineering effort and subsequent installation costs, Module-Level Converters (MLCs) are preferred. The frame-integration, however, rises questions regarding protection and safety of the installation. Assuming the converters cannot be serviced after installation, a high reliability and hence fault-tolerance is required. This paper will focus on LVDC pole-to-earth faults in the context of BIPV MLCs. The current state-of-the-art in commercially available systems is given and recommendations concerning the used grounding configuration and protection methodologies are formulated. Focus will be put on the integration and cost aspect of the solutions.status: accepte