The present invention discloses a charging device to minimize power to be wasted at sunset and sunrise in a solar inverter system, and a method for controlling the same. According to the present invention, the charging device, which minimizes the power to be wasted at sunset and sunrise, in the solar inverter system including an inverter unit to convert direct current (DC) power obtained in a photovoltaic module into alternating current (AC) power includes: a charging unit to store power which is not appropriate to the driving of the inverter unit at sunrise and sunset and is to be wasted; and a wasted-power charging circuit unit having an input side connected with a DC link capacitor in parallel and an output side connected with the charging unit to transmit power generated from the photovoltaic module to the charging unit. The wasted-power charging circuit unit includes a switching module to reduce a DC voltage of the power transmitted to the charging unit, and a charging control unit to calculate DC power and to control the switching module to perform charging for the charging unit when the DC power is less than driving power. According to the present invention, the power which cannot drive the inverter unit at sunrise and sunset to be wasted can be not only utilized, but prevent a hunting phenomenon.
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