Cell module

A photovoltaic cell assembly that is suitable for use in a dense array concentrated photovoltaic cell module, the assembly including a substrate, a plurality of photovoltaic cells mounted on the substrate, each cell having an exposed surface for acceptance of solar radiation, the cells being arranged in a dense array covering more than 95% of the assembly with active cell area that includes at least one string of cells which are electrically connected together and form a series electrical circuit, and each string including a plurality of straight lengths of cells that form rows, with an end cell of one row of cells being electrically connected to a cell at the beginning of a successive row of cells, and a by-pass diode associated with each cell to allow the cell to be by-passed in the electrical circuit in the event that the cell fails or has low illumination, the diodes being positioned in the shadows of the cells, and the diodes providing direct pathways for heat and electricity from the cells to the substrate, and the substrate being a multiple layer substrate including an electrical insulation material layer, a top metalized layer and a bottom metalized layer respectively on opposite top and bottom faces of the electrical insulation material layer, the top metalized layer comprising a plurality of mounting pads in each row on which the cells are secured, with at least 90% of each cell being maintained in thermal contact with the substrate via the mounting pads, each cell being mounted on one of the mounting pads, each mounting pad including a section that extends under a neighboring cell in the electrical circuit, the by-pass diode for the cell being positioned beneath and in the shadow of the neighboring cell and mounted on a section of the mounting pad that extends under the neighboring cell, the diode being electrically and thermally connected to the substrate via the section of the mounting pad, and the diode being electrically and thermally connected to the neighboring cell.