Energy Density Challenge: Solar panels, even the most advanced ones, do not provide sufficient energy density to power large commercial aircraft. This fundamental limitation is a significant barrier to the development of solar-powered passenger planes.

Weight and Storage Issues: The weight of batteries required to store solar energy for night-time and cloudy conditions adds significant weight to the aircraft, which in turn demands more energy to keep it airborne, creating a vicious cycle.

Current Use Cases: Solar power is more feasible for smaller, lighter drones or experimental aircraft that do not have the same energy requirements as commercial passenger planes. These applications serve as testbeds for future advancements.

Future Prospects: While solar-powered passenger planes are not currently viable, ongoing research in improving solar efficiency and energy storage solutions may eventually lead to breakthroughs. Innovations in other areas, such as hybrid-electric propulsion, could also contribute to more sustainable aviation.