Review of Low-Carbon Planning and Operation of Solar District Heating Systems

Solar district heating systems (SDHS) represent a key approach to achieving sustainable and low-carbon heating solutions. To enhance the technical capabilities related to low-carbon planning and operational optimization, this paper first introduces the typical configuration of SDHS, critically reviews the current status and practices of solar district heating system planning (SDHSP), and proposes a conceptual planning framework to support performance-based decision-making. Subsequently, the paper conducts a literature review on two key issues of this framework: carbon accounting and operation strategy/model optimization. The review summarizes commonly used carbon accounting methods and evaluation indicators, as well as representative optimization models applied in SDHS planning. The findings reveal that further research is needed on life cycle carbon emission accounting, dynamic modeling across multiple time scales, and the applicability of alternative optimization models. This study is designed to help expand the use of solar district heating technologies and back the sustainable, low-carbon evolution of heating systems.