Solar
What are photovoltaics?
Photovoltaic (PV) cells are solid-state
semiconductor devices that convert light directly
into electricity. They are usually made of silicon
with traces of other elements and are first cousins
to transistors, LED's and other electronic devices.
How does it work?
A PV device (generally called a solar cell)
consists of layers of semiconductor materials with
different electronic properties. In a typical
BP Solar crystalline cell the bulk of the material is
silicon doped with a small quantity of boron to
give it a positive or p-type character. A thin layer
on the front of the cell is doped with phosphorous
to give it a negative or n-type character.
The interface between these two layers contains
an electric field and is called a junction.
Light consists of particles called photons.
When light hits the solar cell, some of the
photons are absorbed in the region of the
junction, freeing electrons in the silicon crystal. If
the photons have enough energy the electrons
will be able to overcome the electric field at the
junction and are free to move through the silicon
and into an external circuit. As they flow
through the external circuit they give up their
energy as useful work (turning motors, lighting
lamps, etc.) and return to the solar cell. The PV
process is completely solid state and
self-contained. There are no moving parts and
no materials are consumed or emitted.Solsum Series (SSR)
