photovoltaic (CPV) solar cells utilize inexpensive optics
to concentrate sunlight onto small area photovoltaic chips;
this improves the conversion efficiency and reduces the area
of silicon or other expensive semiconductor materials used
in the manufacture of CPV modules by a factor of 100 or more.
However, concentrators need additional expensive equipment
that is required to track the position of the sun in sky to
within the accuracy of one degree.