
56 The Rising Sun in a Developing World
structures: as a result of their lower efficiency, a larger area is
required to generate a unit of power.
As far as concentrating PV is concerned, the family of GaAs solar
cells was developed further from the 1976 laboratory prototypes
with their efficiencies of 22 percent. By 2009, an impressive
efficiency of 42 percent was announced by Spectrolab—a record
for this kind of material. It is interesting to note that among the
hundreds of PV manufacturers today that particular company in the
US is one of the very oldest.
What limiting factors exist for producing inexpensive PV? The
principal one is the cost of the glass