Dear Colleagues,

When looking at the roadmap to achieve the 2050 European energy and climate sustainability goals for renewable energy, the most recent trends of CO2 emissions and energy efficiency indicate that R&D efforts must combine electricity and heat at the global and local levels.

For this purpose, a multi-energy approach to energy generation and conversion is required to release the full potential of intermittent renewable energies.

In this context, certainly electrical and thermal energy storage plays a key role, as it allows not only to manage properly the mismatch between the daily and seasonal demand and the local thermal and electrical generation (mainly based on solar energy) profiles but also to enhance the limited programmability of the generation and variability of thermal and electrical load demands. Therefore, hybrid storage (i.e., storage of electricity and heat) is indispensable for creating flexibility, allowing to optimize the balance between supply and consumption profiles at the lowest cost.

The complexity and multidisciplinary characteristics of hybrid storage systems require research efforts to propose synergy and multidisciplinary investigations linking industrial engineering, material science, building physics, electrical engineering (e.g., smart grids).

Storage technologies (electrochemical, thermal, mechanical, etc.) have heterogeneous features and performances; therefore, it is essential to explore different technologies in order to develop a wide range of alternatives, for which a techno-economical assessment is also available.

The main goal of this Special Issue is to report an updated view of the research status about the integration, optimization, and operation of building energy systems that include hybrid storage technologies, optimize supply, storage, and demand of electricity and heat, and increase the self-consumption of local renewable energy.

The topics of interest in this Special Issue on hybrid energy storage systems (HESS) include (but are not restricted to):

• HESS applications in stationary systems
• HESS in microgrids
• HESS in photovoltaic/thermal (PVT) systems
• HESS structure/topology
• HESS control
• HESS modelling
• HESS design based on field data
• HESS efficiency improvement
• HESS optimal sizing and optimal management
• Short-term and long-term economic assessment of HESS
• Life span assessment of HESS components

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• HESS applications in stationary systems HESS in microgrids HESS in photovoltaic/thermal (PVT) systems HESS structure/topology HESS control HESS modelling HESS design based on field data HESS efficiency improvement HESS optimal sizing and optimal management short-term and long-term economic assessment of HESS life span assessment of HESS components