Solar panels rely on sunlight to generate electricity, so they would not be effective on Mars or other planets with limited sunlight. However, Mars does receive sunlight, although it is significantly weaker than what we experience on Earth due to the greater distance from the Sun and the planet's thin atmosphere.
When designing missions to Mars or other planets, engineers take into account the reduced solar energy available. They optimize the design of solar panels to capture as much sunlight as possible and maximize their efficiency. They may also use advanced technologies, such as multi-junction solar cells, which can convert a broader spectrum of light into electricity.
In situations where sunlight is scarce or unavailable for extended periods, alternative power sources are employed. These can include nuclear power sources, such as radioisotope thermoelectric generators (RTGs), which convert the heat produced by radioactive decay into electricity. RTGs have been used on several space missions, including those exploring Mars, to provide power in locations where solar panels are not feasible.
For future missions to planets with even less sunlight or where sunlight is entirely absent, such as the outer planets or their moons, solar power would become impractical. In these cases, other power sources, such as advanced nuclear systems or energy storage technologies, would need to be employed to meet the energy requirements of the spacecraft or future human settlements.