FYI,

"History: Photovoltaics Timeline"
About.com
http://inventors.about.com/library/inventors/blsolar2.htm

: 1958: Hoffman Electronics achieved 9% efficient PV cells. Vanguard
: I, the first PV-powered satellite, was launched in cooperation with
: the U.S. Signal Corp. The satellite power system operated for
: 8 years.

: 1959: Hoffman Electronics achieved 10% efficient, commercially
: available PV cells and demonstrated the use of a grid contact to
: significantly reduce series resistance. Explorer-6 was launched
: with a PV array of 9600 cells, each only 1 cm x 2 cm.

: 1961: The UN conference on Solar Energy in the Developing World was
: held. The precursor to the PV Specialists Conference, the Meeting
: of the Solar Working Group (SWG) of the Interservice Group for
: Flight Vehicle Power, was held in Philadelphia, Pennsylvania. The
: first PV Specialists Conference was held in Washington, DC.

: 1964: The Nimbus spacecraft was launched with a 470-W PV array.

: 1965: Peter Glaser, A.D. Little, conceived the idea of a satellite
: solar power station. Tyco Labs developed the edge-defined, film-fed
: growth (EFG) process, first to grow crystal sapphire ribbons and
: then silicon.

: 1966: The Orbiting Astronomical Observatory was launched with a
: 1-kW PV array.

: 1968: The OVI-13 satellite was launched with two CdS panels.

Mark Reiff