Statistical analysis of power generation of semi-transparent photovoltaic (STPV) for diversity in building envelope design: A mock-up test by azimuth and tilt angles

Abstract

Semi-transparent photovoltaics (STPVs) have received increasing attention as an energy-efficient building envelope that uses renewable energy. It is necessary to find the optimal combination of the azimuth angle and tilt angle to install the STPV and to secure high-power generation. However, various constraints limit the installation of STPVs at optimal angles. In other words, there may be a conflict between the building envelope design and STPV design depending on the circumstances, thereby limiting the design. Therefore, this study presents a statistical analysis of power generation with respect to angle to determine the possibilities in building envelope design. Two identical STPV modules each were installed at five azimuth and tilt angles (i.e., two STPV modules each on 25 sides), and the power generation for one year was measured. Then, 1392 h of data were sampled and a statistical analysis was conducted to compare the power generation. First, the representative values were set after comparing the power generation of the two modules at each angle through the Mann–Whitney test. Then, the power generation of each angle was compared through the Kruskal–Wallis test, and a post hoc analysis was conducted. As a result, power generation for five azimuth angles (e.g., +90° (west), +45° (southwest), 0° (south), −45° (southeast), and −90° (east)) was statistically identical in performance at tilt angles of 3° and 15°. Therefore, it is more desirable to focus designs on securing more area than considering optimal azimuth angle in the generation of maximum power through STPVs, at tilt angles of 3° and 15°. Moreover, STPVs for the tilt angles of 75° and 90° were statistically identical in performance when facing west, southwest, southeast, and east. This suggests that, when an STPV is installed at 75° or 90° of the tilt angle, if it cannot be installed on the south, it will provide statistically identical performance even if it is installed at any other azimuth angle. In light of these findings, this study concludes by providing guidelines for the application of STPVs in early architectural design.