Comprehensive investigation of rooftop photovoltaic systems in apartment buildings: Focus on installation status and generation performance in South Korea

Abstract

Rooftop photovoltaic (PV) systems in residential buildings play an essential role in reducing on-site electricity demand and promoting energy efficiency. While adoption has increased in recent years, the absence of robust policies for proper operation and maintenance presents a barrier to maximizing their potential. Inadequate management often leads to performance degradation, undermining both environmental and economic benefits. To address this issue, the present study investigates the installation characteristics and actual power generation performance of rooftop PV systems in South Korea apartment buildings, including existing ones. Despite the significant challenge posed by the severe lack of detailed data, such as design drawings, installation status, and applied system information, particularly for existing buildings, this study made extensive efforts to collect as much data as possible. Furthermore, this research integratively analyzed representative variables affecting power generation performance, including PV module performance, installation, and maintenance quality, which have not been comprehensively addressed in previous literature. These variables were categorized into constructional, installation, operation and maintenance (O&M) factors. This integrated approach enhances understanding of the factors contributing to reduced power generation and supports the identification of effective countermeasures. The analysis revealed that single maximum power point tracking (MPPT) central inverters were frequently used regardless of environmental conditions, and approximately 20 % of installed systems had arrays oriented in different directions. While most systems showed good performance with an average daily yield of over 3.54 h/d, about 30 % exhibited signs of degradation. Four major causes were identified: mismatch, data loss, shading, and hardware defects. This study provides qualitative and quantitative analysis from the energy supply side, a perspective often lacking in policy discussions, and was conducted to reduce the gap between policy and research.