NOVELTY - The unit (1) has a plastic shell acting as a support/floor or lateral panel/support for constructions, where the plastic shell includes parts (1B, 1C) in specific shapes. The parts are interlocked with each other to replace beams and a polystyrene floor for eliminating a thermal bridge. The plastic shell comprises a set of inner ribs (2) for imparting self-supporting ability to the unit, where the inner ribs are formed under a surface (9) to create ventilation/water passages (8). The ribs create cavities (3) inside the unit for holding the beams, electric wires and hydraulic pipes.    USE - Modular unit for creating load-bearing structures that is utilized as construction/support for a multilayer solar carpet (all claimed) in modular solar house.    ADVANTAGE - The unit allows a solar carpet to be mounted to a plastic support instead of metal support/bitumen sheets, thus allowing one-time application of the solar carpet without a thermoplastic load-bearing or containing support by laying rigid surfaces over desired areas, and ensuring chemical bonding at lateral ends with water tightness. The unit utilizes a continuously extruded load-bearing floor that replaces the beams, and blocks the polystyrene floor such that the extruded load-bearing floor is utilized as lateral infill panel/support panel, thus providing high thermal insulation and high sound insulation. The unit utilizes the solar carpet to avoid the need for skilled labor, thus reducing costs.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a process for obtaining a modular unit    (2) a multilayer solar carpet    (3) a process for making a multilayer solar carpet    (4) a load-bearing structure.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional perspective view of a modular unit for creating load-bearing structures and for use as a construction/support for solar carpets.    Modular unit (1)    Parts (1B, 1C)    Inner ribs (2)    Cavities (3)    Ventilation/water passages (8)    Surface (9)