## 1 Introduction  
It is estimated that, in the coming years, the consumption of electricity for cooling in buildings will grow, which is attributable to several factors, such as: the increase in ambient temperature, the growth of comfort expectations, the perception of increased productivity linked to thermal comfort, and increased internal load due to electronic equipment. This increase in energy consumption due to refrigeration systems will result also in a significant increase in CO\({}_{2}\) emissions. The aim of Article 9 of the 2010 Energy Performance of Buildings Directive (EPBD) [1] is that all new buildings have nearly zero energy needs by the end of 2020. It also establishes that the low amount of energy required by buildings should be supplied to a significant extent from renewable sources. Solar cooling systems agree with this idea since it makes sense cooling the buildings with the same energy that causes much of the conditioned spaces cooling load. This solution is especially suitable for commercial buildings where there is a coincidence between the hours of cooling demand and the hours of solar radiation availability. Solar cooling will account for 17% of world air conditioning by 2050 according to the International Energy Agency [2]. However, the initial cost of thermal solar cooling systems with absorption machine is very high with payback times higher than their lifetime [3]. Nowadays, from an economic point of view, the vapor compression systems driven by photovoltaic solar collectors are the most attractive solar air conditioning systems [4]. For residential applications in Central Spain, [PERSON] and [PERSON] calculated an investment cost of 1050-1550 euros per kW of cooling capacity for the PV and vapor compression system and 2675 euros per kW of cooling capacity for the thermal solar cooling system with flat-plate solar collector and single-effect absorption machine. In addition to their economic feasibility, photovoltaic (PV) solar collectors combined with electrical chillers with a high energy efficiency ratio (EER) need smaller heat rejection systems. This avoids the risk of legionella associated to the use of cooling towers with LiBr-H\({}_{2}\)O absorption chillers and the corresponding water consumption [5]. These are the main reasons why most thermal solar cooling facilities currently in operation are part of demonstration projects. The performance of thermal solar air conditioning systems is usually evaluated through detailed simulations, which require specific software to establish the system's model. Possibly the most well-known simulation tool for solar thermal systems is Transient System Simulation Tool (TRNSYS) [6], which is a widely used modular simulation program. Solar cooling facilities are complex systems that are better designed with the help of detailed simulations [7]. The model of the LiBr-H\({}_{2}\)O single-effect absorption chiller is important to simulate a thermal solar air-conditioning system. TRNSYS includes an absorption chiller model in its library that needs a specific input file based on performance data provided by the manufacturer. This fact limits its use when those data are not available [8]. The design of a solar air conditioning facility basically involves the design of the solar collector field and the storage tank [9]. Detailed models have been developed in the environment of TRNSYS and used for the analysis of the effect of the main design variables on the performance of the thermal solar cooling facility [10]. These models sometimes include the control system [11]. Simplified methods have also been developed to evaluate the long-term performance of solar cooling systems in terms of the solar fraction. [PERSON] and [PERSON] [12] developed the \(\varphi\), f-chart method for closed-loop systems with finite storage where the load (thermally-driven cooling machine) is characterized by a minimum useful temperature.