Throughout history, humans have harnessed the power of the sun to perform a variety of tasks, but today the need for solar energy has never been more critical. While scientific advancements have recently brought other clean energy solutions to the table, the use of solar thermal energy continues to be a reliable, proven technology.
Although the first solar hot water system in Chicago has been in use for more than twenty years, the recent rise in natural gas prices has sparked a renewed interest in solar thermal systems.
"When natural gas prices spiked, solar thermal panels suddenly became cost-effective," says Hans Detweiler, a policy advocate at the Environmental Law and Policy Center in Chicago. "More people have started to install them, and they’re saving money."
What is Solar Thermal?
The concept of solar thermal energy was born in 1767 when Swiss scientist Horace de Saussure invented the world’s first solar collector. De Saussure’s "hot box" was a miniature greenhouse constructed of five square boxes of glass decreasing in size in order to stack inside each other. After exposing the boxes to the sun for several hours, de Saussure measured the temperature inside each one and found the outermost box was the coolest while the temperature increased in each succeeding smaller box. The innermost box registered the highest temperature at 189.5 degrees F.
"Solar thermal" describes technologies that use the heat of the sun to heat water. Solar collectors covered by tempered glass trap the sun’s heat (similar to how the inside of a car heats up when sitting in the sun), which is then transferred to water either directly or through the use of another fluid (usually water or antifreeze is heated as it is pumped through copper tubes in the collectors), and a heat exchanger. The heat exchanger then transfers the heat to the water storage tank. The solar-heated water in the storage tank can be used immediately or later for normal hot water needs.
Solar thermal systems and solar electric systems are different and should not be confused. Solar electric or photovoltaic systems convert some of the energy in sunlight directly into electricity through the use of photovoltaic (PV) cells made primarily of silicon. Electrons are excited by the light and move through the silicon, which is known as the photovoltaic effect. The result is direct current (DC) electricity, unlike solar thermal systems, which concentrate heat and transfer it to a fluid.
Solar Thermal in Action
Solar Service is Chicago’s oldest company specializing in solar thermal systems. Brandon Leavitt runs the company with more than twenty-five years of experience in the solar thermal industry. In 1977 Leavitt designed and installed the Chicago area’s first solar hot water system, which is still in use today. According to Solar Service, four hours of sunlight in Chicago can produce a twenty-four-hour supply of hot water seven out of every ten days.
One of Solar Service’s residential installations is a home in the 2900 block of West Pratt, Chicago. A four-panel system in operation since 1985 provides both heat and hot water. "There’s absolutely a difference in our gas bill," says the homeowner. "We’ve seen up to a 50 percent savings on a per month basis."
Solar thermal systems are excellent for small-scale residential applications, but are also ideal for commercial use. Estimates indicate that approximately 250,000 commercial and industrial buildings in the U.S. currently use solar thermal systems to provide hot water or space heating.
An example of commercial use is St. Rose Hospital in San Antonio, Texas. The hospital uses a solar thermal system designed and installed by Sun Trapper Systems, Inc., which provides 90 percent of the hospital’s hot water needs using 5,000 square feet of flat-plate solar collectors. The system is capable of holding 9,000 gallons of heated water at one time, and is estimated to save the hospital almost $17,000 a year compared to the alternative of using a steam boiler fired by fuel oil.
Illinois Grant and Rebate Program
The Illinois Department of Commerce and Community Affairs (DCCA) offers a rebate program and a grant program in order to encourage investment in, and the development and use of, renewable energy resources within the state of Illinois — including solar thermal energy.
Eligible applicants include associations, public and private schools, colleges and universities, not-for-profit organizations, and individuals located within the state of Illinois.
Applicants for solar thermal energy systems may apply for a renewable energy rebate by meeting the requirements of any of the following:
• Any new solar thermal water heating system that has been approved by the Solar Rating and Certificate Corporation (SRCC) or a comparable organization and is designed to produce in excess of one kilowatt or equivalent or contains at least twenty square feet of collectors.
• Any new solar thermal space heating system that has been approved by the SRCC or a comparable organization and is designed to produce in excess of four kilowatts or equivalent or contains 100 square feet of collectors.
The DCCA may provide up to, but not more than, 50 percent with a maximum rebate of $5,000 in funds for a single solar thermal energy project. If the user’s utility does not assess the Renewable Resources Trust Fund charge to its customers, the rebate is not available.
Owners of solar thermal systems may also apply for a renewable energy grant by meeting the requirements of any of the following:
• Any new solar thermal water heating system that has been approved by the SRCC or a comparable organization and is designed to produce in excess of sixteen kilowatts or equivalent or contains at least 400 square feet of collectors.
• Any new solar thermal space heating system that has been approved by the SRCC or a comparable organization and is designed to produce in excess of twenty-three kilowatts or equivalent or contains at least 800 square feet of collectors
The DCCA may provide up to, but not more than, 50 percent with a maximum grant of $150,000 in funds for a single solar thermal energy project. Only one grant per proposed renewable energy system project will be awarded to a grantee. If the user’s utility does not assess the Renewable Resources Trust Fund charge to its customers, the grant is not available.
A Bright Future
Solar thermal systems are already economically competitive in most applications, but future technological advances will significantly increase potential markets. Scientists at the University of Chicago have developed a system to deliver solar radiation concentrations of over 60,000 times the intensity of the sun. The system uses a mirror to focus sunlight on a lens which concentrates the light further. Potential applications include powering lasers for space communication, and destroying toxic chemicals.
In the meantime, you can start saving today with a solar thermal system. For more information on Solar Service call 847-677-0950 or 773-763-5716. For more information on DCCA’S grant and rebate program, and an application, contact Rex Buhrmester at 217-557-1925 or click here.