The first solar energy systems were developed by Bell Laboratories in the 1954.  They were an important part of the early space program in the 1950's and 1960's to power satellites.  These early systems cost millions of dollars.  A few years later during the energy crisis of the 1970's solar energy was seen as an alternative to fossil fuels on Earth.  During this period the cost of solar energy was reduced to about $20 per kilowatt-hour.  Marijuana farmers in Northern California used solar PV to power grow lights.  Over the next 40 years the cost of solar energy has dropped to 20-30 cents per kilowatt-hour.  Currently only .01 percent of the electricity in the U.S. is produced through photovoltaic systems.  This will substantially increase over the next few decades.  Solar energy is in the process of moving from a boutique industry marketed to wealthy environmentalists to a viable industry for the main stream.