## 5 Results and Discussion
From the simulations, \(I_{mp}\), \(V_{mp}  
An array of five modules, each comprising three cells, was designed to enhance output power, achieving a \(P_{max}\) of 650 mW at 6.1 V and 108 mA. MATLAB-based (Figure 19) and ADS-based (Figure 20) simulations illustrate \(V_{oc}\) of 6.4 V and \(I_{sc}\) of 110 mA. Assuming an irradiation of 1000 W/m\({}^{2}\), the cell's efficiency is 48%; therefore, using (28), the efficiency of each module is found to be 11% and for the array is calculated as 44% using (30). The integration of MIMO RF and solar energy harvesting is crucial due to their complementary nature. This ensures continuous power availability for IoT applications under varying environmental conditions. While perovskite solar cells provide high-efficiency energy conversion during sunlight hours, RF energy harvesting remains effective even in low-light scenarios, such as cloudy or rainy days. This dual-source approach significantly enhances system reliability and minimises power interruptions. Figure 21 showcases the hybrid energy harvester's performance, merging a MIMO setup with a PSCs array, predominantly during daylight when the perovskite cells reach peak output. It indicates the hybrid system's capability to produce significant power during the day, powering IoT devices and storing surplus energy in a storage unit, particularly with the 16 MIMO configuration. During low-light conditions, only the RF subsystem of the hybrid operates, generating lower power. Nevertheless, the excess energy stored  
Figure 19: I-V and P-V characteristic curve of the perovskite-on-Si tandem solar array with MATLAB simulation. Figure 20: I-V and P-V characteristic curve of the perovskite-on-Si tandem solar array with ADS-based simulation. during high-light periods can be utilised. Since both subsystems function concurrently, the hybrid system's efficiency can be computed using (33), accounting for the efficiencies of both the array and RF-EPH. Hence, the hybrid energy harvester attains an efficiency of 90%. One of the primary challenges in using both sources simultaneously is efficiency optimisation. Perovskite solar cells can generate sufficient power during peak sunlight, potentially overshadowing RF harvesting. However, in scenarios where solar energy is unavailable, such as during night-time or heavy cloud cover, RF energy harvesting can sustain IoT devices [49]. To address efficiency concerns, an intelligent power management unit (PMU) will be incorporated to dynamically regulate power distribution, prioritising solar energy when available and switching to RF energy when solar input is insufficient. This hybrid approach allows for continuous and resilient energy harvesting in diverse environments, making it a viable solution for large-scale IoT deployments. Evaluating the impact of environmental factors is crucial for ensuring the efficiency and stability of the hybrid RF-PPV energy harvester when moving from simulation-based analysis to real-world deployment. While simulations provide valuable insights into theoretical performance, practical implementation must account for variables such as temperature fluctuations, humidity-induced degradation, and RF signal attenuation due to atmospheric conditions. A detailed investigation of temperature effects on perovskite photovoltaic cells was evaluated in [57; 58; 59], focusing on the power conversion efficiency and degradation mechanisms at varying temperatures. PSCs exhibit strong thermal stability between 20 \({}^{\circ}\)C and 55 \({}^{\circ}\)C, with a low power temperature coefficient of \(-0.25\%\)\({}^{\circ}\)C\({}^{-1}\), outperforming \(c-Si\) solar cells [59]. In the practical aspect of this study, advanced encapsulation techniques will be employed to protect perovskite materials from thermal stress (for temperature > 55 \({}^{\circ}\)C) and prolong operational stability. High humidity levels can also accelerate perovskite degradation, reducing efficiency over time [60].