## 5 Conclusions  
The accumulation of thermal energy in the form of latent heat is currently quite a widespread topic to investigate. PCMs are used for latent heat accumulation. Their \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Medium** & **Amount** & **Sensible Heat** & **Latent Heat** & **Total** \\ \hline Water & 800 L & 66.96 MJ & - & 66.96 MJ \\ PCM & 200 L & 6.84 MJ & 38.88 MJ & 41.65 MJ \\  & 1000 L & 73.8 MJ & 38.88 MJ & 112.68 MJ \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Parameters of hybrid tank of water–PCM (salt hydrate). Figure 30: Comparison of hybrid tank capacities. segmentation is wide and there are a number of different types with different parameters. Since each group of PCMs has different properties, each group has its advantages and disadvantages for use in energy storage. The biggest disadvantage is their low thermal conductivity, which causes uneven melting and solidification; moreover, the main problem with heat transfer during a phase change is the boundary level. There have been many studies around the world that have looked at ways to improve thermal conductivity. In this work, the improvement of the thermal conductivity of paraffins by using different elements such as a copper matrix, a steel matrix or a copper spiral was described. For each element, measurements designed to monitor the increase in the thermal conductivity of melting and solidification were carried out. Overall, the results were positive and each of the elements led to acceleration of the melting and solidification of the samples, either in a greater or lesser proportion. The most suitable measured variation was the copper matrix PCM sample, at a copper matrix-to-PCM volume ratio percentage of 6.1% in a laboratory beaker. The solidification rate of the PCM was 75.13% faster than that of the reference sample. Similarly, these results were also measured for an experiment on a larger accumulation tank with a PCM storage tank, where into the PCM tank was integrated a copper matrix, where the percentage of copper matrix to PCM volume was 1.3%. These differences were clearly visible and confirmed again that the copper matrix placed in the PCM tank increased the heat transfer coefficient, and thus, the total phase change time for solidification was reduced by 79.19% and melting by 54.7%; therefore, it is one of the best options to increase the thermal conductivity of paraffin as a PCM for hybrid storage tanks. The integration of a copper matrix into the PCM tank proved to be the most effective solution, increasing the latent heat transfer from 55,677.6 ] to 125,274.6 ], which signifies a 125% enhancement over experiments with pure PCM. An analysis using hysteresis curves revealed that the copper matrix not only improves heat transfer but also stabilizes the thermal response of the PCM across cycles of charging and discharging. This stability is crucial for the practical application of PCMs in energy systems, where consistent performance is necessary to manage peak loads and enhance overall energy efficiency. Considering future research, it is imperative to delve deeper into the microstructural interactions within PCM composites that are modified with metal matrices. Understanding the specific impacts of these matrices on the thermal and physical properties of PCMs will pave the way for targeted enhancements in PCM technology. Additionally, extending numerical simulations to assess the dynamic thermal behavior under varying operational stresses will provide a comprehensive view of their potential in real-world applications. Based on the current research and our experiments, it is important for further development to determine a clear relationship between the volume of the copper matrix and the volume of the PCM by introducing a coefficient that could determine the optimal ratio of the volume structure to achieve the maximum effect.