1. Introduction
Recently, interest in alternative energy has been
increasing due to rise of oil price by limit of fossil fuels
and environment pollution caused by indiscriminate use of
fossil fuels. Compare to traditional energy sources, the
solar energy is limitless and does not generate any
pollution emission. The photovoltaic(PV) system is a
generating system using the photoelectric effect which
changes the light energy into electric energy. And the
performance of PV system is depended on radiation and
temperature. The methods for improvement of PV system
are solar tracking method, MPPT control, improvement of
solar cell performance, and power conversion system [1, 2].
The PV system is composed of program method, sensor
method and hybrid method. The program method is to
track sun's trace by using variable of the time with the
latitude and longitude of geographical locations. And
sensor method using photo sensors is tracked through
difference in amount of light. Hybrid method is using both
program and sensor method [3-5].
In PV system, if shadow is occurred to PV modules then
PV modules operates reverses bias, and will eventually
cause hot-spot [6]. The shadow influence of PV system can
be solved by large PV system installation area. However,
this method causes an increasing installation price. Also, an
inclination angle of the tracking PV system is changed by
altitude angle of sun. Consequently, a length of shadow is
changed by variation of the inclination angle.