A detailed Life Cycle Assessment (LCA) “from cradle to grave ” is performed to a solar combined cooling, heating and power (S-CCHP) system that provides space heating, cooling, domestic hot water and electricity, following two different methodologies (the ReCiPe 2016 Endpoint (H/A) v1.03 and the carbon footprint IPCC 2013 100 years). The innovative S-CCHP system is currently in operation in an industrial building located in Zaragoza (Spain), and the transient model developed to estimate the annual energy outputs has been validated. The system consists of hybrid photovoltaic-thermal (PV-T) collectors integrated via two parallel thermal storage tanks with an air-to-water reversible heat pump (rev-HP). Another contribution is that the detailed LCA analysis is also performed to a conventional PV-system and a grid-based system, viz building electricity consumption supplied from the grid (baseline configuration). The results show that the proposed S-CCHP system has half of the environmental impact of the grid-based system, according to the ReCiPe 2016 Endpoint (H/A) and the IPCC GWP 100a methods (4.48 kPts vs 8.87 kPts, and 82.4 tons of CO2 eq vs 166.9 tons of CO2 eq, respectively). The PV- system has 30% less environmental impact than the grid-based system. Another novelty and contribution are the sensitivity analyses performed to assess the influence of the system lifetime, the solar irradiance and the power generation mix (also known as the electricity mix) on the LCA results. The results show that the proposed S-CCHP system appears as an up-and-coming alternative to reduce the environmental impacts of buildings in all the considered solar irradiance levels and electricity mix scenarios, even in climates with low irradiance levels or in countries with a highly decarbonised electricity supply. 1.Introduction Two of the core objectives driving the energy supply towards deca- rbonised energy systems are i) securing the energy supply and ensuring the reliable provision of energy; and ii) improving sustainability by reducing GHG emissions, pollution, and dependence on fossil fuels [1,2] . The energy union strategy aims at providing consumers with secure, sustainable, competitive and affordable energy [2]. To achieve this, the EU has formulated a low-carbon economy roadmap as a pathway towards reducing emissions by 2050 through commitments without disrupting energy supplies [3]. The roadmap includes, among other initiatives, an increase in the uptake of renewable energy sources (RES) as a fundamental pillar in the ongoing energy transition. Heating and cooling (H/C) is the largest energy end-use sector in Europe, ahead of transport and electricity [4]. H/C in buildings and industry accounts for half of the EU energy consumption (983 Mtoe in 2019) [5]. Most of the building heat demand is for space heating (52%), process heat (30%) and water heating (10%). The demand for space cooling is still small but fast-growing [6]. However, at present, the vast majority of H/C is still generated from fossil fuel combustion, with only 22% generated from RES (in 2019) [5], the majority of which is from biofuels and renewable waste [5]. In this context, the development and implementation of RES for building H/C are essential for displacing fossil fuel utilisation, and thus reducing the associated GHG emissions. Solar energy can contribute to both the electrical and thermal de- mand of buildings using photovoltaic (PV) and solar thermal technolo - gies, respectively. Therefore, solar heating and cooling (SHC) technologies appear as an attractive decarbonisation alternative. Different types of solar thermal collectors (e.g. flat plate, evacuated tube, parabolic through) can be used to harvest solar energy in SHC systems [7-11] . Alternatively, PV systems can be coupled to heat pumps (HP) in solar-assisted heat pump (SAHP) systems for solar heating [12- 14] and solar cooling [15]. *Corresponding author. E-mail address: mherrando@unizar.es (M. Herrando). Contents lists available at ScienceDirect Energy Conversion and Management u{�~zkw! s{yo|kr o>!ÐÐÐ1ow �o�to~1m{y2w{m k�o2ozm{zy kz! https://doi.org/10.1016/j.enconman.2022.115402 Received 10 December 2021; Received in revised form 16 February 2022; Accepted 17 February 2022 Energy Conversion and Management 257 (2022) 115402 2In recent years, hybrid photovoltaic-thermal (PV-T) collectors have been gaining attention both in research and applications. PV-T collectors are particularly attractive for applications in constrained spaces (e.g. in densely populated areas), because PV-T collectors generate both elec- tricity and useful heat simultaneously from the same aperture area [16], with higher overall efficiency than the separate PV and solar thermal systems [17-19]. In addition, the integration of PV-T collectors with H/C technologies has the potential to cover a significant fraction of the en- ergy demand of buildings, as it allows for the simultaneous generation of electricity, heating and cooling [20,21]. Some studies integrate concentrated PV-T [22-25], air-based PV-T [26-29] and water-based PV-T collectors [20,30-32] with H/C technol - ogies. Previous research concluded that solar combined cooling, heating and power (S-CCHP) systems based on PV-T collectors could cover more than 60% of the combined heat demand for space heating and domestic hot water (DHW), along with more than 50% of the cooling needs of households, with reasonable installation areas [33,34]. This work fo- cuses on the LCA of PV-T collectors integrated with heat pumps. Kamel and Fung [28] studied an air-based PV-T collector coupled with air-source HP, where the warm air generated in the air-based PV-T acted as the source of heat production. These authors concluded that a significant reduction in the electricity costs to run the HP could be achieved thanks to this integration with PV-T collectors. The low density and small heat capacity of air limit improvements in the air-based PV-T collector performance, although this type of collector is attractive in applications where water is in limited supply [35]. Other authors proposed the integration of refrigerant-based PV-T collectors with HPs, which can maximize the solar energy utilization and, at the same time, enhance the COP of the HP [36,37]. In such integration, the heat produced by the PV-T collectors is used as the source of an HP [38] to provide space or water heating. For instance, previous authors [39] concluded that almost all the required heating loads in the winter months in Nanjing and Hong Kong (China) could be met using a PV-T-HP system with a variable speed compressor. Zhang et al. [40] analysed the economic performance of a solar photovoltaic/ loop-heat-pipe and HP system for domestic heating and concluded that local utility prices and renewable incentives are critical for the financial feasibility of these systems. Recently, some authors proposed the inte- gration of a roll-bond PV-T collector as the evaporator of a single-stage compression HP for the provision of heat and power in northern China during summer [41]. Reversible HPs (rev-HP) can also be integrated with the thermal output of water-based PV-T collectors [42], increasing the COP in the heating mode in winter [34,43], while in summer, the electrical output generated by PV-T collectors can be used to run the HP to provide cooling [34]. For instance, a water-based PV-T collector integrated with a water-to-water HP to provide space heating and electricity to house - holds was recently proposed [44]. The results showed that increasing the flow rate enhances the total PV-T collector efficiency as also does it increasing the size of the storage tank [44]. Other investigators [45] analysed the performance of a dual indirect SAHP system, with the PV-T collector acting as the evaporator and connected in parallel with an air- source HP, operating simultaneously. The results showed that the PV-T evaporator could compensate for the performance degradation of the air-source evaporator caused by the increasing condensing temperature, while the air-source evaporator could recover heat under low radiation levels [45]. Other studies [12] analysed and compared four alternative SAHP heating systems and concluded that for high electricity prices, PV- T collectors integrated with a water-source HP seemed the best alter- native [12]. Water-based PV-T collectors with micro-channels as ther- mal absorber have also been proposed in the literature. The experimental results of a PV-T collector integrated with water-source HP showed COPs of 3.2 in heating operation mode [46]. There are several environmental-impact analyses of solar thermal [47,48] and PV-T systems [49,50]. However, most of the previous studies assess the environmental payback time (EPBT) [51] and/or the CO2 emissions [52-56], while there are very few studies that perform a complete Life Cycle Assessment (LCA) [57-60]. A recent review [50] concluded that, while some of the works follow the standard ISO pro- cedure for LCA, the method followed is less transparent in most of them. Also, some studies do not include