hexagonal solar cell and module efficiencies, module packing ratio, and solar cell design calculations were made. the cell grid structure and interconnection pattern was designed. the module substrate which includes the aluminum pan, aluminum plate, and mounting brackets were designed and fabricated for the three modules to be used in phase i of this contract program. it was demonstrated that a laserscribe can clearly cut through the p-n junction of the solar cell without causing excessive current leakage across the junction. full hexagons and half hexagons can be cut by laser without causing excessive loss in photovoltaic energy conversion efficiency. the solar cell surface macrostructure study and diffusion study continued. it was demonstrated that surface macrostructures significantly improve solar cell power output and photovoltaic energy conversion efficiency silicon wafer surface preparation and etching time, temperature and concentration was optimized relative to surface macrostructures that trap light efficiently. the spectral response of these cells showed superior light absorption over our commercial solar cell. a diffusion furnace temperature profile study indicates that with only a few modifications to our equipment, 400 silicon wafers per hour can be diffused. a study to determine the optimum silicon ingot diameter to be utilized for modified hexagonal solar cells as a function of the relative silicon material costs, solar cell packaging costs, and solar cell module system costs was completed. a method is presented for determining the optimum low-cost, high ene