Technological advancements have greatly aided in improving the quality of life through a variety of new products and services. Pre-Engineered Building (PEB) is among such technological advancements in structural engineering. Pre-engineered buildings (PEB) are nothing but steel buildings in which excess steel is avoided by tapering the sections as per the bending moment’s requirement. Now the day’s PEB industrial sector is developing very fast, & its growth has increased widely after some years Electricity is very essential for the PEB industrial sector that’s why every PEB industry uses solar power energy through the installation of solar panels on or above the industry rooftop of existing PEB industrial structures. But at that time need to strengthen the existing PEB industrial structure while the industry is in working condition. This paper reviews the analysis and design of existing PEB industrial structures with and without added solar panels load (futuristic load) to them, which have been carried out using STAAD. Pro software & find out the member strengthening requirement base on the STADD Pro results like Bending moment & stress. Two different techniques are currently used to increase or restore the load-carrying capacity of PEB structures: 1) Bonding FRP sheets and 2) welding mild steel plates. Strengthening by mild steel plate is a popular method due to its availability, cheapness, uniform materials properties (isotropic), ease of work, high ductility, and high fatigue strength. This paper suggests various/ different Techniques or sections are used for strengthening existing PEB industrial structures using mild steel sections/ plate (MS). These techniques are Practically possible, economical, optimum, & suitable for the strengthening of existing PEB structures. which are very important to improve the load-carrying capacity of steel structures while adding solar panels load to them. This paper uses Mild steel (MS) Plate welding in different locations/patterns as per the strengthening requirement and will be carried out using STADD Pro & ANSYS Software.