Solar PV, short for "Solar Photovoltaic," gets its name from the process of converting light (photons) to electricity (voltage), which is called the photovoltaic effect. Solar PV systems generate electricity directly from sunlight via an electronic process that occurs naturally in certain types of material, called semiconductors.
In 1954, Bell Labs introduced the first solar PV device that produced a useable amount of electricity, and by 1958, solar cells were being used in a variety of small-scale scientific and commercial applications. Today, the cost of PV has dropped dramatically as the industry has scaled up manufacturing and dramatically improved the technology with new materials. Installation costs have come down too with more experienced and trained installers. However, the U.S. still remains behind other nations that have stronger national policies to shift energy use from fossil fuels to solar. Globally, the U.S. is the fourth largest market for PV installations behind world leaders Germany, Japan and Spain.