Solar energy is the fastest growing energy source in the U.S., and is beginning to upend the utility industry as we know it. In California, Arizona, Hawaii, and many other states the cost of electricity from the sun is now lower than the cost of electricity from the grid, meaning homeowners can have solar panels installed and actually save money. 

What may be shocking to some people is that solar energy is now becoming mainstream. Residential installers like SolarCity (NASDAQ:SCTY.DL) and Vivint Solar (NYSE:VSLR) are cutting costs rapidly and hiring workers like crazy. First Solar (NASDAQ:FSLR) and SunPower (NASDAQ:SPWR) are making a healthy profit for investors by offering technology that's differentiated from that of competitors. There's even a way for conservative investors to play solar, including SunEdison's (OTC:SUNEQ) yieldco TerraForm Power (NASDAQ:TERP), which owns solar projects with long-term energy sale contracts. 

Below are ten facts everyone should know about solar energy that may just change your opinion on solar as an investment.