Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

Abstract

Solar‐assisted heat pumps have the potential to increase the share of renewables in the energy systems for several cases, or to increase the flexibility of smart grids and integrated thermal‐electric grids. The development of such systems requires a comprehensive approach in which technical, market, and social acceptance are all tackled at the same time. Such a holistic approach is the main objective of the present review article. To do so, an investigation is performed by categorizing the integration approaches reported in the literature, exploiting the solar source either as a low‐temperature evaporator source or as supporting the condenser during heating operation. Furthermore, hybrid integration schematics and dual‐source approaches are discussed. Market and social aspects complete the analysis, with the aim of finally identifying the current status; the main drivers and challenges are also addressed. The reported results confirm that the exploitation of solar thermal energy can increase the achievable performance of heat pumps in a broad range of climates. A favorable regulatory/financial framework and informative campaigns for businesspersons and the wide public have been identified as the main solutions to maximize the deployment of the technology in the coming years.

Hybrid System of Photovoltaic and Solar Thermal Technologies for Industrial Process Heat

“…In the DX connection, the ST collector and the HP are joined in one system, where the ST collector acts as the evaporator of the HP. On the other hand, in IDX connection, the ST field supplies heat to the evaporator of the HP by a heat exchanger [30,76,89,[94][95][96][97]. In addition, based on the existence or not of an auxiliary heat source, DX and IDX can be subclassified as single-source and dual-source systems.…”

“…In industrial applications, systems with single source DX configurations have been investigated on an experimental scale in food drying processes [98][99][100].The DX has shown better performance than the IDX configuration in systems with small ST areas [30] and with medium and low levels of solar radiation [95]. Nevertheless, in systems with larger areas of collectors, the larger volumes of refrigerant required, the complexity in the adequate control of the compression cycle and the maintenance difficulties of the system difficulties affect the technical and economic viability of the implementation of DX configurations in applications with industrial scale [30,94,97].…”

“…In this configuration, when the outlet temperature of the ST field is concordant with the heating load requirements, solar heat is supplied directly for the demand. On the contrary, when the temperature is not adequate solar heat is delivered to the cold side of the HP [30,94]. One of the main limitations of single source systems is that the restriction of the evaporator to operate just with the ST collectors reduces the flexibility in the operation of the system and makes it more sensible to the solar energy variability [30].…”