This paper presents an analytical approach to calculate the spacing between the two parallel strings or rows of non-tracked solar Photovoltaics (PV) modules. Shadows of the front row modules fall on the modules of the next row. Optimum distance between the rows has been found for eight different cities of India through the calculations of sun path and length of shadow cast by modules. The shadow length was also calculated throughout the year for every location using MATLAB coding to find the effect of change in gap between consecutive rows on the effective sunshine hours for power generation. It has been found that due to considerably less irradiation incident on the modules during sunset and sunrise, keeping large row gap provides very little gain in energy output while leaving less space to accommodate more modules in the given space. This paper presents analysis of such trade-off between space utilization and solar radiation captured by PV modules.