This chapter discusses PV/T systems with nanofluids and nano-phase change material (nano-PCM) from a design viewpoint. The numerical and energy balance equations are provided, as well as the physical design. In addition, the boundary conditions of a CFD analysis are determined. The element of enhancement of PCM when adding nanoparticles was calculated along with the total PV/T efficiency. Moreover, the methods and methodologies involved in research studies in this topic. Thus, an explanation of the assumptions made and the logic behind each assumption is provided. Moreover, flowcharts for the research activities associated with this topic that covers aspects of research and development such as theoretical analysis, experiments, nanofluid and nano-PCM preparations. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.