Nanostructured materials possess captivating optical features that are crucial for various solar energy usage schemes and technologies. Nanotechnology enables the creation and utilization of structures and systems with dimensions comparable to visible light’s wavelength. This presents numerous opportunities to investigate the novel and frequently resonant phenomena that occur when an item’s size aligns with the electromagnetic field’s periodicity (as determined by the wavelength of light, λ). Several innovative renewable energy technologies are being developed in diverse designs and forms daily. This is a direct response to the growing global recognition of the need for a transition to green energy and the tight targets established for 2050. Solar direct electricity generating systems, such as photovoltaic (PV) and photovoltaic-thermal (PVT) setups, are the most popular emerging technologies in this field. This is because solar energy is widely available and limitless, and recent advancements have made solar cells more efficient and cost-effective. The study in this framework is still in progress, and nanotechnologies are being extensively studied for their potential to improve the performance of solar systems in different configurations and using diverse approaches. This approach is receiving more attention than any other strategy. This chapter attempts to provide a comprehensive overview of research activities involving the utilization of nanostructures, nano-enhanced materials, nanofluids, and similar technologies for solar power generation systems. These systems encompass several components, including solar cells, panel packages, and additional equipment like heat storage devices.