A comprehensive techno-economic analysis of solar energy integration in low-temperature district heating and cooling systems
G. Russo, Andreas V. Olympios, Cesare Forzano, Chandan Pandey, Annamaria Buonomano, Adolfo Palombo, Christos N. Markides
Abstract
This study investigates the integration of solar technologies and energy storage at the individual building level within fifth-generation district heating and cooling networks. Nine distinct building configurations are evaluated, incorporating photovoltaic (PV) systems, solar thermal collectors, photovoltaic-thermal (PV-T) systems, thermal energy storage (TES), and electric batteries. The techno-economic performance of these configurations is assessed for three user types: data centres (thermal prosumers) and residential and office buildings (thermal consumers). To capture dynamic interactions among thermodynamic components, an integrated thermal model is developed using an object-oriented methodology. Key findings for a case study in northern Italy show that combining PV systems with solar thermal collectors and energy storage results in primary energy savings of 57 % for residential buildings and 55 % for offices, compared to a reference scenario without solar technologies. Replacing PV systems with PV-T systems of equivalent area eliminates the need for solar thermal collectors, achieving over 50 % space savings. From a techno-economic perspective, the configuration for residential buildings that combines PV systems, solar thermal collectors, batteries, and TES achieves a payback-time (PBT) of 18 years without electricity exports, reduced to 14 years when excess electricity is exported. For offices, the PV-T system proves more cost-effective, achieving a PBT of 14.6 years, reduced to 11 years with electricity exports. The PBTs observed for the PV-only configuration are 5.9 years for offices and 5.8 years for the data centre. In the community-based approach, where investments are made collectively by users, PV-T systems achieve a low PBT of 6.4 years.