An alternating-current direct-current, AC-DC, photovoltaic device, comprising: a photovoltaic module, a direct current side capacitor, a direct current pulse width modulation, DC-PWM, power switching circuit, and a controller, wherein the direct current side capacitor is connected in parallel with an output terminal of the photovoltaic module; an input terminal of the DC-PWM power switching circuit is connected with the output terminal of the photovoltaic module; characterized in that: the DC-PWM power switching circuit is a full-bridge circuit, the full-bridge circuit comprises four controllable switch transistors S1, S2 S3 and S3, wherein the controllable switch transistors S1 and S3 are connected in series, the controllable switch transistors S2 and S4 are connected in series, and the series of the controllable switch transistors S1 and S3 and the series of the controllable switch transistors S2 and S4 are connected in parallel with the output terminal of the photovoltaic module, a point between the controllable switch transistors S1 and S3 and a point between the controllable switch transistors S2 and S4 constitute output of the DC-PWM power switching circuit; the controller is configured to output a switch control signal to control a switching state of the controllable switch transistor in the DC-PWM power switching circuit, to control the DC-PWM power switching circuit to output from the output of the DC-PWM power switching circuit a direct current PWM wave in a case that the switch control signal is a direct current modulation signal and output from the output of the DC-PWM power switching circuit an alternating current PWM wave in a case that the switch control signal is an alternating current modulation signal. a photovoltaic module, a direct current side capacitor, a direct current pulse width modulation, DC-PWM, power switching circuit, and a controller, wherein the direct current side capacitor is connected in parallel with an output terminal of the photovoltaic module; an input terminal of the DC-PWM power switching circuit is connected with the output terminal of the photovoltaic module; characterized in that: the DC-PWM power switching circuit is a full-bridge circuit, the full-bridge circuit comprises four controllable switch transistors S1, S2 S3 and S3, wherein the controllable switch transistors S1 and S3 are connected in series, the controllable switch transistors S2 and S4 are connected in series, and the series of the controllable switch transistors S1 and S3 and the series of the controllable switch transistors S2 and S4 are connected in parallel with the output terminal of the photovoltaic module, a point between the controllable switch transistors S1 and S3 and a point between the controllable switch transistors S2 and S4 constitute output of the DC-PWM power switching circuit; the controller is configured to output a switch control signal to control a switching state of the controllable switch transistor in the DC-PWM power switching circuit, to control the DC-PWM power switching circuit to output from the output of the DC-PWM power switching circuit a direct current PWM wave in a case that the switch control signal is a direct current modulation signal and output from the output of the DC-PWM power switching circuit an alternating current PWM wave in a case that the switch control signal is an alternating current modulation signal. the DC-PWM power switching circuit is a full-bridge circuit, the full-bridge circuit comprises four controllable switch transistors S1, S2 S3 and S3, wherein the controllable switch transistors S1 and S3 are connected in series, the controllable switch transistors S2 and S4 are connected in series, and the series of the controllable switch transistors S1 and S3 and the series of the controllable switch transistors S2 and S4 are connected in parallel with the output terminal of the photovoltaic module, a point between the controllable switch transistors S1 and S3 and a point between the controllable switch transistors S2 and S4 constitute output of the DC-PWM power switching circuit; the controller is configured to output a switch control signal to control a switching state of the controllable switch transistor in the DC-PWM power switching circuit, to control the DC-PWM power switching circuit to output from the output of the DC-PWM power switching circuit a direct current PWM wave in a case that the switch control signal is a direct current modulation signal and output from the output of the DC-PWM power switching circuit an alternating current PWM wave in a case that the switch control signal is an alternating current modulation signal.