Silicon Valley firms are driving a sizzling $11 billion worldwide market in solar energy, part of a rapidly expanding alternative-energy economy that promises to shake up the way power is produced and consumed as profoundly as the region’s computer and Internet companies upended global communications and commerce in the late 20th century.

Fears about global warming have triggered public and political demand for renewable energy, which is expected to become a $167 billion global market by 2015.