Photovoltaic (PV) systems generally incorporate fixed-mount modules that maintain an immovable orientation throughout the year. However, this does not optimize energy output, as the solar irradiance received by modules depends on the sun's position and atmospheric conditions. To address this issue, an improved optimization approach for adjustment of the monthly tilt angle (TA) has been proposed in this research work, aiming to decrease energy prices while increasing PV output power. It develops an improved mathematical model of TA that allows the installation of the maximum number of PV modules within a given area while avoiding the shading effects. In contrast to existing work, the proposed work incorporates module efficiency, the PV system's cost, and site-specific variables such as geographic coordinates, month, land area, declination, and azimuth angles in the developed model. By considering these parameters, this work has implemented a monthly adjustment of the TA to achieve a monthly optimized tilt angle (OTA) using MATLAB software. The results and comparison with existing work illustrate that the proposed work has significantly contributed to the reduction of the LCOE while simultaneously enhancing the power generation of a PV system for five geographically distinct locations that signify the diversity of climatic conditions in the country's central, southern, northern, eastern and western regions. In comparison to existing literature, the percentage reduction of LCOE has been achieved at 195.14% for the central region (plain), 196.952% for the southern region (desert), 195.176% for the northern region (hilly area), and 197.612% for the western region (coastal). Similarly, the increase in output power has been achieved at 3.78%, 8.84%, 1.66%, and 2.11% for the central region, southern region, northern region, and western region respectively.