Experimental Investigation of Optimal Wavelength Selection for Laser Power Beaming Using Silicon Solar Cells in UAV Charging Systems

Unmanned aerial vehicles (UAVs) are a rapidly growing sector and widely utilized across various industries including agriculture, military applications, disaster monitoring, aerial photography and mapping. However, the primary limitation of UAV operation is the flying time. Laser power beaming technology is one of the most promising approaches for extending the endurance of unmanned aerial vehicles (UAVs) by enabling wireless in-flight charging. The overall system efficiency is highly dependent on the spectral compatibility between the laser source and the photovoltaic receiver. This study investigates the wavelength-dependent performance of polycrystalline silicon solar cells to determine the most suitable operating wavelength region for laser-based UAV charging systems, since laser sources emit monochromatic light. The spectral response of a 5cm² silicon photovoltaic cell was analyzed over an absorption range of 365–1030 nm using a VK-SS-50 LED solar simulator and a VK-PP-100 PV analyzer. The major electrical parameters measured include open circuit voltage (Voc), short circuit curren t(Isc), and maximum power (Pmax). During monochromatic testing, the irradiance was maintained across all wavelengths to ensure a fair spectral comparison. The results indicate that the output power of the solar cell varies with the wavelength of the incident light. Under the one-sun illumination, the maximum power output of the solar cell was measured as 75.84mW. Under the individual monochromatic lighting conditions, the minimum power output was recorded at 445nm with a value of 0.29mW, while the maximum power output was 6.4mW at 810nm. Based on these findings, the optimum laser wavelength region for power beaming using silicon solar cells lies between 810nm to 880nm. This near infrared (NIR) region is advantageous for long-distance power transmission due to reduced atmospheric losses. Furthermore, combining multiple laser sources at different wavelengths, rather than a single one, could further enhance the output power of silicon photovoltaic receivers.