The invention provides a method and device for detecting the power supply state of a solar panel and a vehicle. The method includes the steps that the illumination intensity on the solar panel is detected; the illumination quantity in a preset time period is calculated on the basis of the illumination intensity; the illumination quantity is compared with a preset illumination quantity standard value, and if the illumination quantity is lower than the preset illumination quantity standard value, it is judged that that the solar panel cannot be in an effective power supply state; the information indicating the state that the solar panel cannot be in the effective power supply state is sent. By means of the method and device, users or operation and maintenance staff can know the state of the solar panel in time so that the solar panel on the vehicle can be more effectively managed.