The first use of solar cells in space occurred on the satellite Vanguard 1, which was launched on March 17, 1958. Eight tiny panels were installed symmetrically around the satellite to ensure power generation during the satellite's random tumbling. They delivered fifty to one hundred milliwatts of power and provided secondary electricity for a . Each panel had six square silicon cells, measuring 2 centimeters (0.79 inch) by 2 centimeters (0.79 inch) by 0.4 centimeters (0.16 inch), with a (PV) conversion efficiency of approximately 10%. The panels of solar cells were protected by a thick cover glass to avoid radiation damage from electrons and protons trapped in the that surround Earth. The longevity of Vanguard 1's beacon signal surpassed all expectations—lasting until May 1964. As a result, future regulations required shutting down satellite power supplies to avoid cluttering the radio wave spectrum with unwanted signals from satellites no longer in use.

The early use of solar cells was tentative, but they eventually emerged as the primary power source for satellites that were required to operate for more than a few weeks. While radioactive materials can, and have, been used to power spacecraft, their use can be problematic since the radioactive material is inherently quite dangerous to humans and other life forms. Because of the potential harm those radioactive substances can

pose to people for long periods of time if they are accidentally released into the environment, so-called atomic batteries (also referred to by other labels, such as radioisotope generators) are not used in the vast majority of spacecraft presently in use.

Solar cells improved steadily and successfully met the unique power requirements of space travel while other possible competitive sources were proven unfeasible for most space missions. Over the years, solar cells have provided electricity to thousands of space missions that operated near Earth, on the Moon, and in planetary or interplanetary missions.