High Level Shading Research Articles

Impact of shading heaviness on voltage, current and power of the solar photovoltaic string

The short-term power output variability of solar photovoltaic (PV) systems caused by passing clouds is becoming a major concern for grid operators. As the penetration of utility-scale PV systems boosts, the rapid power fluctuations greatly challenge the grid's transient stability. A photo voltaic system is greatly vulnerable to Partial Shading. The performance analysis of PV systems clearly suggests that the maximum power of partially shaded PV systems is inversely proportional to the heaviness of shading. However, some literatures are not of the same opinion; for them, the maximum power of a partially shaded system is invulnerable to shading heaviness, often at certain critical points. According to research on the P-V characteristic curve under various numbers of shaded modules and shading levels, the irradiance of the shaded modules reaches a certain turning point or critical point. The PV array becomes insensitive to high-level shading, categorically for the series topology. This paper presents an experimental results of performance parameters with varying shading heaviness. The experiment is performed on a Photovoltaics string of series connected modules, a 119KW grid-connected rooftop solar power plant using the Power Quality analyser for continuous recording of various parameters under changing shading heaviness. The degree or heaviness of shading decides the critical point. The critical point can vary based on the number of the shaded modules.

Developing a weather responsive internal shading system for atrium spaces of a commercial building in tropical climates

In response to the non-trivial problem of overheating in glass roofed buildings in low latitudes a study was undertaken to reduce discomfort and high energy consumption in a large atrium building in China. This paper reports on the development of a shading system designed for that building as a remedial solution to reduce temperatures while maintaining adequate levels of natural lighting in the atrium spaces of a large multifunctional commercial building. The effects of the shading system on both the physical indoor environment and its economic implications were analysed using implemented models. Calibrated with the data measured in the building during the hottest season, summer, the models were used to test both thermal and lighting performance of two shading arrangements: high and low level blinds in both open and covered modes on typical overcast days and clear days in summer and winter respectively. Also tested were two types of fabric used for the blinds.The performance of these tested cases was assessed for solar gain, cooling loads, internal surface temperatures, air temperatures and operative temperatures of both ground floor and surrounding walkways on various levels within the atrium, the major circulation areas. The results reveal that the high level shading, with blinds fixed close to the glazed roof are generally less effective in the provision of thermal and lighting conditions of the atrium, than the low level shading, where blinds are fixed 3–5 m below the glazed roof to form a ventilated void. The financial benefits of these remedial solutions were also assessed using standard economic analysis methods to provide recommendations on their costs and payback periods.