<p>As the demand for renewable energy sources grows, integrating solar-powered systems offers a promising solution. However, conventional photovoltaic (PV) panels typically convert only 15-20% of incident radiation into usable energy. Consequently, scientists worldwide are actively researching ways to improve panel performance and achieve higher energy efficiency by optimizing solar radiation flux density. This experimental study presents the design of a mobile photovoltaic-thermal device with an autonomous energy supply system. It details the results of experiments aimed at increasing electrical energy efficiency by testing a water-based cooling system for the module surface. The article also provides and analyzes time-dependent graphs of parameters such as short-circuit current, open-circuit voltage, solar radiation flux density, and ambient temperature, along with formulas for calculating the electrical and hot water energy obtained from the experiments. Additionally, this experimental research presents the results of trial tests conducted on a photovoltaic-thermal device with a power of 600 W and a useful surface area of 3.25 m2. This device is designed for small-scale electricity and hot water supply to both populations located far from centralized energy grids and social facilities engaged in mobile activities. The findings indicate that using additional reflectors to increase the incident <br /> solar radiation flux density on the experimental setup boosted the amount of solar radiation reaching the surface by 1.8-2.0 times. Additionally, by employing water as the working fluid in the mobile photovoltaic-thermal device’s collector, the panel surface temperature was reduced by 1.2-1.5 times. Based on experimental findings, a mobile photo-thermal device with an autonomous energy supply typically achieves an electrical energy output efficiency of 14.3% and a thermal energy efficiency of 73%.</p>