Advancements in hybrid heating systems for residential applications

Heating and cooling account for a significant share of energy consumption, particularly in the European Union, where they account for almost half of total energy consumption. The energy demand for heating and cooling is mainly driven by space, process, and water heating, with a growing demand for space cooling. Fossil fuel technologies currently dominate in buildings, with renewable energy sources contributing only 24.8% of consumption in 2022 (Energy 2024). In order to reduce greenhouse gas emissions and increase the share of renewable energy, the development and implementation of renewable technologies for heating and cooling in buildings is crucial. An interesting and promising approach to the use of renewable energy sources is their use in hybrid systems. These can often combine the advantages of different technologies while mitigating their disadvantages. Hybrid heating systems increase energy efficiency, reduce environmental impact, and improve system reliability by integrating multiple renewable energy sources. Combining technologies such as solar, biomass, and heat pumps has great potential to optimize energy use, stabilize thermal output, and reduce primary energy consumption. This article reviews previous work on the integration of different renewable hybrid systems for residential buildings. Both stand-alone and grid-connected systems, incorporating various renewable energy sources and storage technologies are reviewed. This work also discusses the control requirements and how advanced and intelligent approaches can help improve performance and energy consumption. Furthermore, it discusses the challenges of hybrid system implementation, such as high initial costs and integration complexities. The novelty of this work lies in its comprehensive assessment of hybrid system configurations, their control requirements, and the role of smart technologies in optimizing their operation. The findings provide valuable insights for researchers, policymakers, and industry stakeholders, guiding future developments in sustainable heating solutions and energy transition strategies.