Alternative storage options for solar thermal systems

Abstract

The efficient implementation of solar systems in buildings depends on the storage of energy yielded, as it can both increase the solar system's autonomy and make it a feasible solution for zero energy buildings, and make storage vessels more compact, reducing precious space requirements. This is of particular important in places with reduced time of sunshine, where solar systems are less effective, because of the deviation between solar radiation and the demand. The traditional storage options use water, which is practical, safe and low-cost, especially when the storage requirements are small. However, when larger storage is needed, limits concerning the use of water exist, mainly due to the need for larger installation space and the increased thermal losses. The use of phase change materials (PCM) for thermal energy storage seems an upcoming technology. The main idea is the substitution of water with PCM, which feature larger specific energy storage capacity compared to other conventional materials. In the context of the specific paper, a combined solar thermal system used for the preparation of domestic hot water (DHW) and space heating (Solar Combi System) with two different types of storage is studied, for two Greek cities. The aim is to find out which is the most efficient way of storing energy with respect to the autonomy of the system, for a solar combi system. This is being achieved by determining the comparative autonomy of PCM and water storage system for various climates. It was proven that using PCM is advantageous, as it can extend the autonomy duration of the solar system for 2 to 8 hours, depending on the season and the climatic conditions. However, it was also seen that in solar combi systems used throughout the whole year, PCM are inefficient during summer period.

Low‐temperature and pressureless in‐situ self‐assembled SiC w / SiC composite ceramics for solar thermal absorber and storage integration

“…Solar thermal power has been the most prospective green power generation technology to alleviate the greenhouse effect and utilize solar energy effectively due to limited fossil resources 1 . Solar thermal power plant consists of three systems at present: thermal absorber, thermal storage, and thermal transfer 2 .…”

Hybrid solar thermal/photovoltaic‐battery energy storage system in a commercial greenhouse: Performance and economic analysis

“…Many researchers have evaluated PV and ST systems as stand‐alone systems 13‐20 and have largely only analyzed simultaneous PV and ST systems on smaller scale applications (ie, residential and smaller commercial). Liao et al 21 studied the economic benefits of a distributed system with PV and BES on the overall life cycle in the context of an industrial zone in Shanghai.…”

“…Solar thermal (ST) collectors can provide heat to cover the heating load, and photovoltaic (PV) modules can provide electricity to meet the electrical loads. 12 Many researchers have evaluated PV and ST systems as stand-alone systems [13][14][15][16][17][18][19][20] and have largely only analyzed simultaneous PV and ST systems on smaller scale applications (ie, residential and smaller commercial). Liao et al 21 studied the economic benefits of a distributed system with PV and BES on the overall life cycle in the context of an industrial zone in Shanghai.…”

Ενσωμάτωση Τεχνολογιών Ανανεώσιμων Πηγών Ενέργειας Σε Κτίρια Σχεδόν Μηδενικής Κατανάλωσης Ενέργειας

“…Εικόνα 5.17 Θεμοκρασιακό εύρος λειτουργίας Υ.Α.Φ., (Kyriaki et al, 2020) Όπως φαίνεται, σε εφαρμογές με απαιτούμενες θερμοκρασίες κάτω από τους 200 °C, οργανικά υλικά όπως οι παραφίνες και οι αλκοόλες σακχάρων καθώς και τα ένυδρα άλατα είναι τα πιο κατάλληλα, ενώ τα υδροξείδια, οι χλωριούχες ενώσεις και τα ανθρακικά άλατα είναι τα πλέον κατάλληλα για εφαρμογές πολύ υψηλών θερμοκρασιών. Παρόλο που υπάρχουν πολλά διαθέσιμα Υ.Α.Φ., η ενσωμάτωσή τους στα συστήματα αποθήκευσης είναι περιορισμένη λόγω του γεγονότος ότι η χρήση τους δεν έχει ακόμα πιστοποιηθεί ενώ παράλληλα το κόστος τους είναι ιδιαίτερα υψηλό.…”

“…μετά από πολλαπλούς κύκλους φορτίσεων και εκφορτίσεων, προκειμένου τελικά να αξιολογηθεί εάν η εφαρμογή τους σε συστήματα αποθήκευσης λανθάνουσας θερμότητας είναι αποδοτική. Οι περισσότερες από αυτές τις μελέτες αφορούν εφαρμογές θερμοκρασιών κάτω από 100 o C, ενώ βρέθηκαν ελάχιστες μελέτες για εφαρμογές άνω των 100 o C (Kyriaki et al, 2020).…”