This paper investigates how the Internet of Things (IoT) can transform solar thermal systems, which is a critical gap in the research because it offers a robust literature review of the integration of IoT since 2010 and 2024. This work is important because it has provided a detailed discussion on the role of IoT in improving real-time monitoring, automation, predictive maintenance, and energy management of photovoltaic panels, solar dryers, solar stills, and solar heaters. An approach of systematic review had been utilized, and more than 142 studies were analyzed to determine the trends, challenges and developments in the field. The findings show that there is a significant growth of the implementation of Solar PVT systems (5% in 2010 and 75% in 2024), energy efficiency, fault detection, and smart grid integration. Moreover, further IoT applications in the field of sustainable energy presence are shown by the development of AI-based optimization, remote access over the cloud, and P2P energy trading. Although these advantages exist, the task of cybersecurity risks, interoperability and high implementation costs still exist. This review brings forward the most efficient software products used in analyzing IoT-based solar, such as the MATLAB/Simulink, LabVIEW, and internet of things platforms, such as the Amazon Web Services (AWS) IoT and Google Cloud IoT. The results can be of great benefit to the researchers and industry participants, as the writers claim that more developments should be made in AI, blockchain security, and low-power IoT devices to fully utilize the potential of IoT in solar thermal use as part of the industry 4.0 model.