Thermal management plays a vital role in ensuring proper function in various engineering applications and systems. Solar systems, power plants, jet and automobile engines, air conditioning and refrigeration systems, and cooling of electronic devices are major areas of research requiring proper thermal management, and so active and passive experimental techniques and theoretical approaches to optimise such thermal components and systems are of significant interest to researchers. The use of nanofluids, enhanced surfaces, nano-coatings, and phase change materials represent promising future advancements in thermal management techniques and the enhancement of solar system efficiency.

An increasingly important area of research is thermal management issues in solar systems, including photovoltaics and solar thermal systems. With the advancement of technology in solar cells and solar thermal systems it is now possible to produce miniature systems, with better utilisation of solar energy per unit area, however, the challenge of thermal management of such systems still remains a pivotal aspect to be resolved, especially as in hot climates such technologies will be limited by rising temperatures and this will be reflected in a decline in performance. Various hybrid systems are being investigated and these show a promising future for hybrid technologies for sustainable and reliable systems.

The aim of this Special Issue is to invite recent experimental, numerical, and theoretical developments in the field of thermal management and efficiency enhancement of solar systems. Another important aspect covered in this Special Issue is the efficiency of solar systems, including photovoltaic and solar thermal-based systems. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Thermal management of photovoltaics
• Nanofluid-based solar systems
• Micro-channels for solar systems
• Phase change materials for thermal management
• Porous media for solar systems
• Convection heat transfer through solar systems
• Efficiency improvement of photovoltaic and solar thermal based systems
• Passive and active solar technologies
• Utilisation of nanotechnology for solar systems