This blog was written by John D. Wilson, former Deputy Director for Regulatory Policy at the Southern Alliance for Clean Energy.Guest Blog | April 21, 2016
Where’s the best place for solar energy? It may not seem obvious to many readers, but Memphis, Tennessee is one of the smartest places to put solar energy in the Southeast. Just this week, the Tennessee Valley Authority (TVA) showed how it is following this kind of smart siting by signing a a 53 megawatt (MW) solar facility power purchase agreement (PPA) with Nashville-based renewable energy provider, Silicon Ranch Corporation, who will construct what is soon-to-be Tennessee’s largest solar array in Millington, TN, just north of Memphis.
What’s so smart about putting solar in the western part of TVA’s service territory? It turns out that on hot summer days, TVA can rely on the sun shining on West Tennessee and Northern Mississippi late into the day – producing solar energy just when air conditioners across the entire Tennessee Valley most needs this clean energy to keep folks cool. The maps below show two ways of mapping the output of a solar farm. The left represents the “usual” view, which emphasizes how much solar energy is actually generated. On the right, the “utility” view, which emphasizes how much energy is produced during the hours that TVA has the highest demand.
The Millington, Tennessee project will be located at almost the exact on-peak location SACE tested in the analysis that produced the maps above. This location is exactly where we found the 2nd highest value for peak demand output in the Southeast – 68.8% of total system output. On an annual basis, the type of system that Silicon Ranch will install usually produces around 23-24% of maximum potential output over the course of a year, when you factor in nights and cloudy days. But when power is needed most, the Millington solar array should deliver an average of about 65-70% of total potential output, even into the late afternoon. It’s important to keep in mind that TVA’s entire system peak occurs a bit earlier than sunset in Memphis because most of TVA’s system is to the east – by siting solar in the western end of the system, this project provides the late afternoon sun that TVA needs.
“The Southern Alliance for Clean Energy applauds the announcement of Tennessee’s largest solar project as a significant step towards increased deployment of clean, affordable solar energy in the Tennessee Valley,” said SACE Executive Director Dr. Stephen A. Smith. “SACE has identified West Tennessee as the prime location for high efficiency, high performing solar power and has advocated for use of more advanced technologies, like single-axis tracking solar panels. TVA is beginning to recognize the value that solar brings to their energy infrastructure and ratepayers alike, and SACE is hopeful that we will continue to see more projects like this awarded throughout our Southeastern region.”
The 53 MW project will be located at the Naval Support Activity Mid-South base in Millington, Tennessee, just north of Memphis. The solar array will provide clean, affordable energy to TVA customers over the next 20 years, generating enough energy to power 7,500 homes! The new array will be more than 10 times the size of the state’s current largest array located on I-40 near Stanton, TN, and will consist of 580,000 solar panels.
This project highlights the partnership of advances in technology, local economics, and the continuously lowering cost of solar. Construction on the project will begin once transmission facilities have been built and will result in an estimated 300-400 jobs. The project will use single-axis tracking solar technology that will allow the panels to rotate throughout the day, following the arch of direct sunlight, making the panels highly efficient.
It is also worth noting that this action begins to address requests made by SACE and many people from the Memphis area, who pushed for TVA to find cost-effective solar and other renewable energy solutions to replace the Allen coal plant in South Memphis. TVA made the decision to replace that plant in August 2014. We look forward to learning more about this project as it progresses and SACE will continue to be a strong advocate for increased solar development in and around Memphis, as well as the rest of the Southeast region.