NOVELTY - The substrate (110) has a set of grooves (112) placed on a surface of an electrically insulate body, where the grooves are spaced from each other and accommodate a solar cell (120). A set of conductive wires (130) is placed on the body and between the grooves, and connects the solar cell. An electrode layer is placed on a side wall, and another electrode layer is placed on another side wall. The electrode layers are connected through the conductive wires. A reflector i.e. continuous reflection layer, is insulated from the electrode layers.    USE - Solar cell system substrate for use in a solar cell system for carrying, supporting and connecting solar cells e.g. silicon-based solar cells, gallium arsenide solar cells and organic thin film solar cells.    ADVANTAGE - The substrate allows the material of the electrode layers to be opaque to avoid leakage of incident light passing through the electrode layers, thus improving photoelectric conversion efficiency of the solar cell. The substrate allows thickness of a transparent insulating layer that is in a range from about 10 nanometers to about 50 nanometers to reduce light absorption. The substrate is electrically insulated to prevent the solar cell from short circuit.    DETAILED DESCRIPTION - The reflector is made of metal selected from a group consisting of aluminum, gold, copper and silver. The body is made of material selected from a group consisting of glass, quartz, silicon, ceramic, rubber, polymer and wood. The conductive wires are made of metal, conductive polymer, carbon nanotube and silver paste. The body is a semi-cylindrical shaped/hemispherical shaped body. The former electrode layer is a continuous planar shaped structure.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic top view of a solar cell system including a set of solar cells electrically connected in series and a substrate defining a set of grooves.    Solar cell system (10)    Solar cell system substrate (110)    Groove (112)    Solar cell (120)    Conductive wire (130)