Phase change materials (PCMs) have emerged as promising solutions for latent heat thermal energy storage (LHTES) systems, offering considerable potential for storing energy derived from renewable sources across various engineering applications. The present study focused on optimization of solar cooling system by integrating LHTES with different PCM tank configurations. TRNSYS simulation software was selected for the study, and the collected experimental data from laboratory system prototype were used for system validation. The results indicate that the use of PCM led to a noteworthy decrease of 6.2% in auxiliary energy consumption. Furthermore, the time during which the heat carrier temperature flow exceeded 90 °C from the storage tank to the auxiliary fluid heater was extended by 27.8% when PCM was utilized compared to that of its absence. The use of PCM in LHTES is more effective under variable weather conditions. On the day when changes in weather conditions were observed, around 98% of the cooling load was provided by produced sun energy. The results of the research can be used to optimize the solar cooling system, which will help reduce the environmental impact of cooling systems running on non-renewable fuels.

In the last ten years a 10% increase in the energy consumption in Latvia has been observed; this means increasing import of electricity and energy resources, since the volumes of electricity produced in Latvia are insufficient for covering the electricity demand. The energy demand, being ever increasing, along with the limited fossil fuel reserves as well as environmental pollution and global climate changes, has aroused an active interest in renewable energy resources. In the world, a tendency is developing fast – that of the necessity to replace, step-by-step, the traditionally employed energy carriers by those of higher quality, with inclusion of renewable energy resources - biomass, hydro, wind and solar energy. This would undeniably lead to the cost reduction for the RES use technologies, which, in turn, would mean increase competitiveness and wider utilization. A part of electricity, about 70% of the total electricity consumption in Latvia, is generated by hydro plants and combined heat and power plants, an insignificant part is produced by small hydro power stations and wind generators, and the rest is imported from abroad

The national priority axis is increase of renewables (RES) use in Latvian Energy sector; therefore, new solutions for Electricity, Heat and Cold production are sought for. Solar energy is available at the same time when there is need to cool rooms, so Solar Cooling systems are suitable also for Latvian conditions. In Latvia such systems are not used yet, so it is important to assess the potential of these systems.The sunlight duration and intensity depends on the season, weather conditions and geographical position of a country. As compared with the annual global solar radiation incident on horizontal surfaces in sunny regions (2200 kWh/m2), in the northern Europe is half as much (1100 kWh/m2). The solar energy potential defined for Latvia as technically achievable by 2020 is: for electricity 0.01 TWh and for heat 0.04 TWh.As shown by experimental studies, the application of solar collectors in Latvia can give good results. The energy of solar radiation can be employed for 1700-1900hours annually. Due to a gradual increase in the comfort level, the demand for space cooling will grow in the near future. Solar cooling can be an alternative for electrically-powered compression-type chillers that currently are the most common in the Baltic States. The solar cooling system installed in the Institute of Physical Energetic is the first of the type in EU which is built at the latitudes higher than 55 degrees of north.Taking into account the fact that there were no systems plants of this type at so “cold” latitudes, first of all the models in PolySun were to be validated, and a dynamic simulation program containing the five-years meteorological data was to be developed. The solar cooling system has been optimized using multiple simulations. The influence of the system's different elements on its operation is evaluated. The optimal model developed for the given climatic conditions is described

Phase change materials (PCMs) have emerged as promising solutions for latent heat thermal energy storage (LHTES) systems, offering considerable potential for storing energy derived from renewable sources across various engineering applications. The present study focused on optimization of solar cooling system by integrating LHTES with different PCM tank configuration. TRNSYS simulation software was selected for the study and collected experimental data from laboratory system prototype was used for system validation. The results indicate that the use of PCM led to a noteworthy decrease of 6.2% in auxiliary energy consumption. Furthermore, the duration during which the heat carrier temperature flow exceeded 90°C from the storage tank to the auxiliary heater was extended by 27.8% when PCM was utilized, compared to its absence. The use of PCM in LHTES is more effective under variable weather conditions. On the day when changes in weather conditions were observed, around 98% of the cooling load was provided by produced sun energy. The results of the research can be used to optimize the solar cooling system, which will help reduce the environmental impact of cooling systems running on non-renewable fuels.

Information on the electrical-driven solar air conditioning (SAC) is rather scanty. A considerable body of technical data mostly concerns large-scale photo-voltaic solar air conditioning (PV-SAC) systems. Reliable information about the energy output has arisen only in recent years; however, it is still not easily accessible, and sometimes its sources are closed. Despite these facts, solar energy researchers, observers and designers devote special attention to this type of SAC systems. In this study, performance evaluation is performed for the PV-SAC technology, in which low-power (up to 15 kW_p of cooling power on average) systems are used. Such a system contains a PV electric-driven compression chiller with cold and heat sensible thermal storage capacities, and a rejected energy unit used for preheating domestic hot water (DHW). In a non-cooling season, it is possible to partly employ the system in the reverse mode for DHW production. In this mode, the ambient air serves as a heat source. Besides, free cooling is integrated in the PV-SAC concept.

Today, the fastest growing end-use in the buildings sector is cooling demand, notes the International Energy Agency (IEA). In the last few years, the interest in solar cooling systems has been growing globally. Solar cooling systems are the next solution to meet the growing demand for air conditioning. The literature analysis shows that solar cooling systems mainly use single-stage absorption chillers, with water as the working fluid, and only a small fraction of them use phase change materials to improve heat storage. Based on previous studies on solar-assisted cooling systems, the use of phase change materials for thermal storage should be investigated. The paper will present a study of a solar cooling system with the optimized PCM thermal storage, with the aim of stabilizing the operation of heat storage, taking into account the volatility of solar energy, the impact of short-term operations and peak hours on the amount of heat produced. This means that the amount of electricity consumed to heat up the accumulation tank will be significantly reduced. The optimization model in simulation software will be performed to test solar cooling system with latent heat storage, with aim to investigate the efficiency of the developed latent energy storage and provide technical guidance for the implementation of such system in the practice. All indicators, including environmental impact and economic calculations, will be identified in order to determinate the specific systems for foresight market uptake.