## 2 Case Study and Scenario Characterization  
In the period of June-July 2017, we conducted a field campaign to assess the baseline energy situation of Toconao. The village population was about 800 inhabitants, grouped into 332 households. It comprised 32 commercial activities--such as restaurants and small grocery stores--a public school, and 6 public offices. Electricity was supplied by diesel-fired generation units from the nearby village of San Pedro de Atacama, yet the cost of electricity tariffs were more than double the national average and the supply was subject to frequent blackouts, typically lasting for several days and necessitating reliance on a 320-kW diesel backup generator. LPG bottles, delivered to the village by trucks on a weekly basis, represent instead the main source for the supply of thermal energy for final uses. As seen for electricity, the gas price is also significantly higher than the national and regional average [38] due to its isolated location. Overall, the village shows a marked dependency on expensive, non-renewable, unreliable, and imported primary energy sources. In addition, it is worth noting that an estimated more than half of the total final energy consumption is due to thermal demand--in accordance with the abovementioned global trend--mostly driven by DHW loads. On the other hand, the area is characterized by a significant solar energy potential due to its latitude and height above mean sea level, with a total annual global horizontal irradiation of 2578 kWh/(m\({}^{2}\)-year).  
Figure 1 presents a conceptual scheme of the village and the energy carriers considered in this study. Toconao will be considered as an isolated country and the International Energy Agency's (IEA's) energy accounting method [39] will be adopted to estimate the Total Primary Energy Supply (TPES) entering the system.  
We propose four configuration scenarios (summarized in Figure 2) to analyze how different energy system architectures may improve the energy cost, the overall energy efficiency of the village, the renewables penetration, and the dependency on import, namely:  
(a) Traditional energy system, in which all main energy needs (electric and DHW) are satisfied by means of the current mix of sources and technologies, i.e., diesel generators and LPG boilers.  
(b) Conventional micro-grid, in which a typical hybrid micro-grid (including photovoltaic (PV) panels, batteries, and diesel generators) is installed to only supply purely electric loads, while DHW loads are covered by LPG boilers. This configuration scenario is defined to represent the mainstream strategy adopted in the framework of off-grid projects, which rarely take into account non-electric loads.  
(c) Multi-good micro-grid, where the hybrid micro-grid is sized in order to meet all the energy needs of the village, hence including DHW loads, which are in this case supplied by means of electric heaters.  
(d) Integrated multi-energy system, where solar thermal collectors, hot-water tanks, and LPG boilers are coupled with the hybrid micro-grid to serve DHW loads. The micro-grid can also interact with the thermal energy system through electric resistance heating elements installed inside hot-water tanks. In this configuration, electricity can be thus stored both directly, in battery banks, and indirectly, in hot-water tanks for thermal use.  
It is worth specifying that the possibility of cogeneration from the diesel generators is not taken into account within the scenarios, due to the absence of a centralized heat distribution network and to the low realism of assuming the construction of such an infrastructure in the context of interest.  
Figure 1: Conceptual scheme of the village of Toconao for energy accounting purposes.