Taco Burrito King Inc. previously installed a solar energy system at its Belmont, Ill., location. Company President Salvador Lamas was so impressed with the system that he had it installed in the chain's newest Niles, Ill., location as well, which is set to open Friday, the Medill Reports of Northwestern University reported.

The 10-panel system makes the Niles Taco Burrito King the state's largest solar hot water system in a restaurant.

Ted Lowe, secretary of the Illinois Solar Energy Association, said solar thermal energy systems are long-lasting and greatly reduce long-term energy bills. He said for businesses that use a large amount of water on a regular basis, if they can afford the initial investment, it will benefit them for years to come.

"With solar thermal, the more you use it, the faster it pays for itself -- it's unlike anything else that I know of. If you take money out of your wallet, it doesn't go flying back in there, right?" Lowe said.

Brandon Leavitt, owner of Solar Service Inc., the solar energy system provider that installed the Taco Burrito King systems, said a 10-panel system will likely result in annual energy savings of $2,500 to $3,000, which he said is a 20 percent return on investment.