An experimental solar cell of 1954 held into the sun at a laboratory bench by a window in New Jersey, a hand in a white shirt sleeve holding a square plate of red-brown pressboard four centimetres across, on it a round dark blue-grey silicon disc two and a half centimetres across with a mirror-bright bluish surface, a green and a red thin wire from the edge of the disc to two nickel solder tags with brass screws, the wires running on to a meter in a Bakelite case turned away from the lens, a small tin toy Ferris wheel on the bench, sunlight from the right through a window with glazing bars.
What it was used for
The Bell Solar Battery was demonstrated on 25 April 1954. Its first use was not domestic but telephonic: the Smithsonian holds a module used in a test installation at Americus, Georgia, to power a rural telephone relay. A Bell advertisement in Radio-Electronics of January 1956 describes the installation: 432 specially prepared silicon cells, cushioned in oil and covered by glass, mounted on a line pole; by day it supplied power directly to the line and also charged a storage battery for night use. Popular Electronics in October 1954 named as intended applications power supplies for low-power mobile equipment and battery chargers at amplifier stations along rural telephone systems. The same advertisement gives the reason for the pairing: transistors require little power, and this power can easily be supplied by the solar battery.
What was new
What was characteristic was the efficiency, not the effect. The photovoltaic effect had been known since Becquerel in 1839, Fritts built selenium cells in 1883, and Russell Ohl at Bell found a p-n junction in silicon by accident on 23 February 1940; his patent on a light-sensitive electric device was filed on 27 May 1941 and issued on 25 June 1946. The American Physical Society's tally: Fritts's selenium cells under 1 per cent, Ohl's silicon sample about 1 per cent, the 1954 cell about 6 per cent. Popular Electronics gives 50 watts per square yard. At first it barely sold. John Perlin reports that in 1956, at $286 for a 1-watt cell, Chapin calculated that a home-owner would have to pay $1,430,000 for an array large enough; the only commercial success was novelty items such as toys and transistor radios, and it was the space age that saved the technology.
What the sources leave open: Accounts of the place of the announcement differ: the American Physical Society writes Murray Hill, New Jersey, a museum timeline New York City. John Perlin speaks of a press conference in April 1954. The exact installation date at Americus appears only on a historical marker; the duration and end of the field trial are not documented. The original paper by Chapin, Fuller and Pearson was not accessible.
Connections
Every connection names its kind. “Forerunner” on its own would be a claim.