The invention provides a solar module which is composed of a surface sealing film, a transparent adhesive film, a solar cell, a lightweight adhesive film A and an isolated substrate which are stacked from the top to the bottom in order; and the isolated substrate is composed of an isolated film, a carbon-fiber sheet, a lightweight adhesive film B, a honeycomb core, a lightweight adhesive film C and the carbon-fiber sheet which are stacked from the top to the bottom in order, wherein the honeycomb core inside also needs to be appropriately added embedded parts according to concrete operating requirements. The technical scheme of a preparation method of the solar module comprises following steps: (1) making use of an oven to match with a vacuum air pump to process a pre-compacting treatment for a carbon-fiber prepreg; (2) meanwhile, processing a welding sequence of the solar cell; (3) processing a cutting sequence; (4) processing a laminating technology treatment; (5) processing post treatment procedures which in order are: removing raw edges, embedding strakes, arranging a junction box, measuring high voltage, cleaning the surface, measuring photo-electrical output characteristics, classifying components, and examining the appearance. The solar module has the advantages of lightweight, high efficiency and good low-temperature characteristics, and being very suitable to being applied in the stratosphere.