“Solar energy currently provides only a quarter of a percent
of the planet’s electricity supply, but the industry is growing at staggering
speed. Underlying this growth is a phenomenon that solar’s supporters call
Swanson’s law, in imitation of Moore’s law of transistor cost. Moore’s law
suggests that the size of transistors (and also their cost) halves every 18
months or so. Swanson’s law, named after Richard Swanson, the founder of
SunPower, a big American solar-cell manufacturer, suggests that the cost of the
photovoltaic cells needed to generate solar power falls by 20% with each
doubling of global manufacturing capacity. The upshot is that the modules used
to make solar-power plants now cost less than a dollar per watt of capacity.
This means that in sunny regions such as California, photovoltaic power could
already compete without subsidy with the more expensive parts of the
traditional power market. Moreover, technological developments that have been
proved in the laboratory but have not yet moved into the factory mean Swanson’s
law still has many years to run.”
