While solar cells have been around in some form since the 1800s,
increases in their efficiency were modest and slow until about
2000. Since 2000, the technology has seen rapid increases in
efficiency, both at the research and consumer levels, and
consistent deceases in cost of approximately 7 percent per
year.
For all of these improvements, however, solar power has a
significant inherent flaw – it generates energy at a very
variable rate that is highly dependent on environmental conditions.
Wind turbines, which have similarly improved in both efficiency and
affordability in recent years, suffer from the same flaw.
New large-scale battery technologies promise to store energy
both as it is being generated and in a distributed fashion
throughout electrical grids. Early adoption of these new
energy-storage technologies is beginning with some of the first
large-scale projects beginning construction in California, Nevada,
Texas, New York, and Hawaii. These technologies
