## 3 Results and Discussion
### Drying Process Results  
The volume of water extracted from the product during each drying cycle can be calculated [52]. Approximately 109 liters of water are eliminated in every full-load drying cycle. An absorption machine, with a dehumidification capacity of 52.8 kg per 24 h, is sized according to this volume. Each drying cycle has a duration of 23.5 h, essentially spanning one day. Alongside the absorption machine, a reversible compression heat pump rated at 9000 BTU is employed to regulate the temperature within the drying chamber, maintaining it between 10 and 30 \({}^{\circ}\)C. The contribution of the air conditioning unit to dehumidification is not factored into the sizing of the photovoltaic dryer. The solar dryer is engineered to fulfill its annual energy requirements using electricity generated by photovoltaic panels installed on the roof and facades of the drying structure. The system comprises six modules on the roof and another six on the south elevation, with each module providing 500 W of power. The photovoltaic generator has an annual energy output potential of 8383 KWh, with strings 1 and 2 yielding 4407 kWh and 3976 kWh, respectively. The total electrical energy demand for each drying cycle, which includes operating temperature and humidity sensors, the PLC, and LED lighting, is 190 kWh. In summary, the photovoltaic dryer is designed to effectively remove moisture from the product while adhering to the renewable energy constraints set by the photovoltaic generator, ensuring a sustainable operational model. The dehumidification process commenced at 9 a.m. on 31 May 2024 and concluded at 8:30 a.m. on 1 June 2024, lasting less than a day (refer to Figure 5). Initially, the relative humidity (RH) in the drying chamber was 41%, which dropped to 8% after approximately 24 h, during which the door was opened for inspection. The temperature (T \({}^{\circ}\)C) started at 22.5 \({}^{\circ}\)C, then decreased before gradually rising to 25 \({}^{\circ}\)C when the door was opened for checking. Data collected by sensors were transmitted via Wi-Fi to a ThingSpeak account, allowing for real-time monitoring of the drying process. These data included fluctuations in product moisture content and drying rates. The Wireless Sensor Network (WSN) was instrumental in providing decision support throughout the drying process, enabling precise tracking of moisture loss and drying rates for both ro  
Figure 5: Drying chamber profiles in a single day. At the conclusion of the drying cycle, the moisture content was measured at 15% for sage and 17% for rosmary. The fresh-to-dry weight ratio was 100/41 for sage and 100/62 for rosmary, with the final weights of the dried biomass being 32.6 kg for sage and 63.7 kg for rosmary. These results are similar to those conducted with solar drying of the medicinal plants integrated with phase change storage material [44; 45]. The comparison between SSDs and conventional drying methods for aromatic crops reveals significant advantages of the former in multiple areas. Drying times for basil and sage were substantially reduced using SSD, with times of 58, 46, and 32 h at temperatures of 30, 40, and 50 \({}^{\circ}\)C, respectively, compared to 96 h outdoors and 144 h indoors with traditional methods [76]. In terms of energy consumption, SSD demonstrated savings ranging from 25.54% to 77.1% when compared to conventional methods [76], with energy use for lemongrass and lavender recorded at 27.72 kWh and 43.02 kWh, respectively, at 50 \(\pm\) 2 \({}^{\circ}\)C [77]. Furthermore, SSD outperformed conventional methods in terms of product quality, with better color retention (15.60 \(\pm\) 0.89 for lemongrass) and higher essential oil content for lemongrass (1.96%), thyme (1.73%), marjoram (3.40%), and lavender (2.76%) at 40 \({}^{\circ}\)C [77]. SSD also exhibited lower microbial load for basil and sage at 40 \({}^{\circ}\)C. From a cost perspective, SSD was more economical, with drying costs per kilogram of chili being 39% lower than those using a cabinet dryer [78].