Overview on different approaches for supervisory control strategies, deciding on operating modes and set points for the controls of the different plants and components integrated in solar thermal systems.

Overview on different approaches for the control of the heat distribution networks in case of the integration of large-scale solar thermal systems, and different possibilities for the reduction of the operating temperatures in DH systems.

Subtask A “Network analysis and integration” focuses on the overall aspects of district heating and cooling networks with integrated solar thermal (ST) technologies. Particularly important are the cases in which the solar share is such to significantly influence the operation of the network and the other heat/cold supply units. In the present factsheet, the best-practice examples collected in the factsheet A-D1.1 are analyzed and compared.

This publication of IEA SHC Task 55 shows 18 best practice examples of Solar District Heating (SDH) systems in six countries worldwide. Additional systems are described in the brochure “Solar Heat for Cities” and in the factsheets A-D3.1 and A-D3.2
 

The present factsheet summarizes the study ”Comparative Analysis and Design of Solar Based Parabolic Trough - ORC Cogeneration Plant for a Commercial Centre” performed by the Universidad de Zaragoza (Spain) and published in 2020 [1]. Two novel solar based PTC-ORC cogeneration systems, producing power and cooling, were pre-designed, considering commercially available pieces of equipment, to cover the annual energy demands of a commercial centre located in Zaragoza (Spain).

This factsheet focuses on large-scale hot water storage technologies adopted to integrate large shares of ST in DHC systems. After an overview of role and integration schemes of large storage systems in existing and future-oriented DHC, the state of the art is described and the highlights of international applications are reported, including a comparison of the different technologies in terms of strengths and weaknesses.

This factsheet focuses on the integration hydraulics and control of central ST systems in DHC. The first part gives an overview of the typical integration concepts and operating modes implemented in the state of the art. The second part illustrates general aspects of the integration of heat pumps to achieve higher shares of ST and describes recent projects: two implementation projects (Crailsheim and Salzburg-Lehen), and one feasibility study performed by the Technische Universität Dresden.

This factsheet focuses on the integration hydraulics and control of central ST systems in DHC. The first part gives an overview of decentral feed-in: international state of the art (including comparison and selection criteria of the different integration schemes), hydraulics and components, details of the return-to-supply scheme (challenges, pump operation, control). The second part describes concepts for the secondary-side integration of ST without feed-in. The third part illustrates selected best-practice examples in Austria (Wasserwerke Andritz and Berlinerring in Graz) and Sweden (Ystad).

Solar thermal (ST) energy is one of the few renewable heat sources that is available almost everywhere and can bring multiple benefits to district heating and cooling (DHC) networks (on an environmental and systemic level) with very low operation costs and risks. However, the current share of ST in DHC networks is almost zero on a global scale.