Climate change poses a pressing threat to the world, and even with immediate action, it will take a long time to reverse. The primary cause of this issue is the unregulated use of energy from fossil fuels, one of the energy resources over the recent decade. However, energy storage and usage challenges hindered the adoption of renewable energy sources. Nanofillers have been incorporated into renewable energy technologies to enhance their performance and solve the problem. These fillers can impart various characteristics, such as mechanical reinforcement, electrical conduction, and optical or thermal characteristics. Nanofillers also improve ionic conductivity in solid-state lithium batteries and boost electrochemical efficiency. However, adding more fillers can decrease reliability and energy density. In addition, nanofillers enhance the pyroelectric and piezoelectric properties of electrospun materials. It has been shown that polymer nanocomposites are a viable alternative for energy-storage dielectric material in pulsed power systems, as they enhance the dielectric energy storage density and breakdown strength of nanocomposite films, and have electrochemical stability window, ionic conductivity, and high thermal stability.