In the early 1950s R.S. Ohl discovered that sunlight striking a wafer of silicon would produce unexpectedly large numbers of free electrons. In 1954, G.L. Pearson, C.S. Fuller, and D.M. Chapin created an array of several strips of silicon (each about the size of a razor blade), placed them in sunlight, captured the free electrons and turned them into electrical current. This was the first solar battery. It could convert only six percent of the sunlight into useful energy; people wondered what it was good for. Today, the solar cells we use to power calculators, highway emergency phones, and satellites can convert over 25 percent of the sunlight that hits them into useful energy.