Solar arrays are the most commonly used spacecraft power system because they are lightweight, efficient, and reliable. They convert sunlight into electricity, which can be used to power the spacecraft's systems.

Solar arrays are lightweight, efficient, and reliable, making them the ideal choice for spacecraft power systems.

Solar arrays are only effective in sunlight, they are expensive to manufacture, and they are susceptible to damage from space radiation.

Batteries are used to provide backup power for spacecraft in case the solar arrays are unable to generate enough electricity.

The main advantage of using batteries for spacecraft power is that they can provide power even in the absence of sunlight.

Batteries are heavy, have a limited lifespan, and are expensive to manufacture.

Radioisotope Thermoelectric Generators (RTGs) use nuclear decay to generate electricity. They are used on spacecraft that are too far from the sun to use solar arrays.

The main advantage of using RTGs for spacecraft power is that they can provide power for long periods of time without the need for refueling.

RTGs are heavy, expensive to manufacture, and produce radioactive waste.

Fuel cells use the chemical reaction of hydrogen and oxygen to generate electricity. They are used on spacecraft that require high levels of power.

Fuel cells are lightweight, efficient, and can provide high levels of power.

Fuel cells require a supply of hydrogen and oxygen, they are expensive to manufacture, and they are susceptible to damage from space radiation.

The International Space Station uses solar arrays to generate electricity.

The Hubble Space Telescope uses solar arrays to generate electricity.

The Voyager 1 and Voyager 2 spacecraft use Radioisotope Thermoelectric Generators to generate electricity.