Generation characteristics of 100 kW PV system with various tilt angle and direction arrays

We report analysis about generation data of a 100 kW PV system. The system consists of seven polycrystalline silicon arrays and three thin-film arrays. The rated power of each array is 10 kW. Thin-film is made of tandem structure comprising amorphous silicon and microcrystalline silicon. For each array, tilt angles are arranged in 10°, 20° or 30°. And directions are facing due south, south-south east 30° and south-south west 30°.We have been analyzing generation data of the system since 2007 to understand the influence of system arrangement. The knowledge we have got until now is below.

(a)

Seasonal annealing occurs in thin-film arrays because thin-film cells contain amorphous silicon. Thus, theoretically, as for reduction of conversion efficiency in high temperature season, reduction of thin-film arrays is smaller than polycrystalline’s. We analyzed the ratio of seasonal generation energy (kWh) by using measured data of the system. Generation energy ratio in summer of thin-film is larger than polycrystalline’s. This is same trend as the theory.

(b)

There is a simulated data of solar irradiation that had been calculated by using meteorological data of 30 years. According to this simulated data, optimum condition of the system is arranged in tilt angle of 28.4° and facing due south. (The system is situated at latitude 33° north.) And simulation data shows that yearly irradiation decreases as tilt angle and direction become far from optimum condition. We analyzed yearly generation energy of each array in the system. Each array’s reduction percentages of generated energy from optimum condition were smaller than simulation value.