An air conditioner using photovoltaic energy is provided. The air conditioner may include a photovoltaic cell for converting photovoltaic energy into Direct Current (DC) power, an indoor unit for exchanging heat, and an outdoor unit for exchanging heat. Photovoltaic power generated by the photovoltaic cell may be supplied to the indoor unit and used as at least one of standby power in a standby mode, consumption power in an automatic photovoltaic mode, or auxiliary power in a cooling mode.