A classified solar charging method defines four magnitude classes of charging current in accordance with a combination selected from four magnitude classes of power production of a solar cell and four magnitude classes of capacity of each rechargeable battery of a rechargeable battery pack. In addition to the optimal charging current, the method simultaneously takes an operating temperature of the rechargeable battery into account upon using the solar cell to store energy in the rechargeable battery. Accordingly, the present invention can selectively charge overall, partial or single rechargeable battery based on the power production of the solar cell and the capacity of the rechargeable battery to enhance a charging efficiency and reduce a charging time.