Knoxville Jail Locks Up One of the Largest Solar Hot Water Systems in the Nation

Stephen Smith | August 2, 2010 | Energy Efficiency, Energy Policy

Contributions to this blogpost were made by SACE’s Lauren Steier and Joanna Malcom of FLS Energy.


A huge solar hot water system was recently installed on Knox County’s Detention Center just outside of Knoxville, TN. This solar thermal system consists of 300 flat plate collectors and will provide hot water to more than 1,000 inmates, which is about 14,000 gallons a day!  It will save the county $60,000 and offset 174 tons of CO2 emissions annually.  Trane, who provides heating and air solutions all over the world, recommended the cost-saving system to Knox County and brought in FLS Energy, a leading turn-key solar energy system provider from Asheville, NC, to install the system. Learn more about solar hot water systems here.

solarthermal2Funding for this  $1.88 million project was provided through the U.S. Department of Energy’s Energy Efficiency and Conservation Block Grant Program (EECBG), as part of the American Recovery and Reinvestment Act (ARRA). The solar thermal system installation is part of $16.2 million in improvements that Knox County launched in collaboration with Trane in August 2009 to address aging infrastructure and high energy and operating costs. The improvements will be completed in January 2011. The county is combining anticipated energy and operational savings with $2.1 million in U.S. Department of Energy’s Energy Efficiency and Conservation Block Grant funds to pay for the improvements.

“The Energy Efficiency and Conservation Block Grant program is an important part of Gov. Phil Bredesen’s strategy to invest in cost-effective clean energy resources in Tennessee,” said Commissioner Matt Kisber of the Tennessee Department of Economic and Community Development. “The EECBG grants will help Knox County to lead by example in their energy conservation efforts, while reducing energy bills in the short term and supporting Tennessee’s rapidly growing clean energy economy in the long term.”

“The solar farm is an important step forward both fiscally and environmentally,” said Mayor Mike Ragsdale. “From the cost-savings, we can provide services to our citizens with money we were using to pay energy bills. Environmentally, we are following the advice of our own Knox County Green Team and tapping into alternative energy sources. In this case, that resource is sunshine, which is readily available here in the south.”

When completed, the improvements will reduce the county’s energy costs an estimated 36 percent by upgrading and enhancing infrastructure in 40 facilities, 24 parks and 37 traffic intersections. In addition to creating one of the nation’s largest solar farms, the improvements are also expected to add county jobs and significantly reduce the county’s environmental impact while providing a more productive and comfortable environment for county employees and residents who use county services.

For businesses or organizations that use large amounts of hot water, solar hot water systems like this one are a great way to incorporate renewable energy into facility operations.  A solar thermal system can provide up to 70-80 percent of a facility’s annual hot water needs.  In many cases, these systems can reduce a facility’s total energy costs by 20 percent, reducing the reliance on standard resources such as electricity, natural gas, heating oil or propane.

Currently, there are financial incentives for incorporating solar thermal technology.  Besides the EECBG financial incentive, solar hot water also qualifies for a 30 percent federal tax credit.  Commercial solar hot water can also qualify for payments in lieu of this tax credit.  More information about this tax credit as well as other state incentives can be found on the Database of State Incentives for Renewables & Efficiency (DSIRE) website.

At its core, a solar thermal energy system is the low-hanging fruit of solar technology, providing a cost effective, clean energy solution.  When solar thermal is compared on a dollar for dollar basis with photovoltaic (electric) technology, solar thermal has a 3:1 advantage in the amount of kWh equivalents it can generate.  Coupled with the available financial incentives, a commercial sized solar thermal system can see returns on investments in as little as 3-5 years.  After that, the system will generate years’ worth of hot water at no cost.

Stephen Smith
Dr. Stephen A. Smith has over 35 years of experience affecting positive change for the environment. Since 1993, Dr. Smith has led the Southern Alliance for Clean Energy (SACE) as…
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