Additionally, the farther the spaceship is from the Sun, the less power the solar arrays are able to gather. Beyond the asteroid belt, current solar array designs are practically useless. Devices called concentrators increase the effectivness of solar arrays at increased distances from the Sun. Batteries Batteries only provide power for short periods of time. Afterward, they must either be recharged, or discarded.
Batteries also tend to be bulky and heavy, which are both drawbacks to their use on space vehicles.
In defense of batteries, they provide a good source of back-up power to solar arrays when the ship is in the shadow of a planet. They can also provide power boosts for one time experiments or other special uses. Fuel Cells Fuel cells convert hydrogen into electricity and water. The water production is the primary reason why fuel cells would be used in a manned space craft design. They provide a large amount of power in a small package.