Verification of the effectiveness of transparent photovoltaics according to the transmittance level in Seoul, South Korea

• Power generation efficiency of transparent photovoltaics (TPVs) is studied. • Daylighting performance of TPVs is also evaluated. • TPV effectiveness in maintaining optimal indoor illuminance is validated. • Optimal TPV transmittance levels are determined for energy savings. Research efforts have been increasingly focused on the application of transparent photovoltaic (TPV) panels to buildings owing to their ability to generate power while enabling light transmission. However, most studies have primarily focused on improving the power generation efficiency while neglecting the need to establish fundamental data for future TPV applications. Therefore, this study evaluated the power generation and daylighting performance of TPVs at various transmittance levels to demonstrate their effectiveness and determine the optimal transmittance. The main findings were as follows: 1) TPVs proved more effective in saving energy compared to monocrystalline single-sided photovoltaic (PV) panels when considering power generation and lighting energy necessary for maintaining optimal indoor illuminance. In particular, the optimal TPV transmittance for power generation and saving lighting energy was found to be 60 %. 2) When maintaining an indoor illuminance of 500 lx, it may be preferable to increase daylighting rather than relying on PV panels. Notably, this study only examined vertical orientations. Thus, adjusting the PV-panel angle could enhance the power generation efficiency. 3) Using TPVs may cause glares in the middle season and winter; hence, the use of shading systems will be necessary. 4) Adjusting TPV transmittance can help overcome indoor illuminance imbalance. Notably, the performance evaluation was conducted under limited environmental conditions; hence, further research is required for a more comprehensive analysis.