Satellites which circle in a spatial orbit around Earth have solar cells to absorb solar energy and convert it to electricity. The temperature of these cells goes high because of the sunlight. PCMs can help control and maintain these temperatures fixed to prevent any damage.
Also, satellites include components placed on heat sinks, which duty is to absorb those components’ extra heat; if the amount of heat and the number of components increase, then bigger heat sinks are needed. By using PCMs in the components, smaller and lighter heat sinks need to be placed to absorb this energy.