NOVELTY - The solar module having a front side and a back side comprises: two first strings each including unequal efficiency bifacial photovoltaic cells (UEB cells) electrically connected in series; and two second strings each including the UEB cells electrically connected in series such that corresponding sides of the UEB cells with the second conversion efficiency face in a first direction. Each of the cells in a first string has one side with a first conversion efficiency and an opposite side with a second conversion efficiency that is smaller than the first conversion efficiency.    USE - The solar module is useful in a photovoltaic unit (claimed) for residential applications.    ADVANTAGE - The solar module exhibits improved solar-energy-to-electricity conversion efficiency and smaller area.    DETAILED DESCRIPTION - The solar module having a front side and a back side comprises: two first strings each including unequal efficiency bifacial photovoltaic cells (UEB cells) electrically connected in series; and two second strings each including the UEB cells electrically connected in series such that corresponding sides of the UEB cells with the second conversion efficiency face in a first direction. Each of the cells in a first string has one side with a first conversion efficiency and an opposite side with a second conversion efficiency that is smaller than the first conversion efficiency. All UEB cells in a first string have corresponding sides with the first conversion efficiency face in the first direction. One of the two first and second strings is electrically connected in parallel. The two first strings are electrically connected in series to form an upper string of UBE cells. The two second strings are electrically connected in series to form a lower string of UBE cells. The upper and lower strings of UEB cells are electrically connected in parallel. A first string is electrically connected in parallel with a second string to form a parallel unit of UEB strings. Two parallel units of UEB strings are electrically connected in series. An operation of solar module, which is characterized by a curve, represents time-dependence of electrical power generated by the module on a sunny day, where a portion of the curve corresponding to electrical power generation before noon is symmetric to a portion of the curve corresponding to electrical power generation after noon when the front and back sides of the spatially-fixed module receive equal amounts of solar energy. The solar module further comprises: a support module juxtaposed with the solar module in such orientation that a first amount of electrical power generated by the module before noon is equal to a second amount of electrical power generated by the module day after noon when the front and back sides of the spatially-fixed module receive equal amounts of solar energy; a first lite of glass (720a) and a second lite of glass (720b) disposed in a parallel and spaced-apart relationship to form a gap between the first and second lites of glass; and a diffractive element in optical communication with UEB cell. The two first strings and the two second strings are located in the gap. A peripheral ring of sealing material sealably connects the first lite of glass and second lite of glass around a perimeter of the module. The module is devoid of a rigid housing juxtaposed with the first and second lites of glass. A number of sides of UEB cells characterized by the first conversion efficiency and facing in the first direction are equal to a number of sides of UEB cells characterized by the second conversion efficiency and facing in the first direction. All sides of the UEB cells corresponding to the front side of the module are coplanar. The rigid housing element is adapted to mount the module to a support. An INDEPENDENT CLAIM is included for a flexible photovoltaic unit.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic side view of a solar module structured as a frameless module.    First lite of glass (720a)    Second lite of glass (720b)    Perimeter seal (724)    Edges. (730a, 730b)