This blog was written by John D. Wilson, former Deputy Director for Regulatory Policy at the Southern Alliance for Clean Energy.Guest Blog | February 19, 2014
Where are the best spots to build solar power in the Tennessee Valley Authority? It turns out, many of them are in Mississippi!
We recently obtained 16 years of simulated solar power production data from Clean Power Research for the Tennessee Valley Authority region, looking at 26 sites scattered from east to west, and north to south in the region. It turns out that the best sites are in the western part of TVA, which isn’t surprising since the sun sets later in the west, and TVA needs power most towards the end of the day.
We were a little surprised to see a site in Kentucky make our “Top 10” solar sites list, since most people tend to think of solar as a resource that performs better as you move south. Turns out that western Kentucky is plenty sunny!
Here are some other things we learned:
The sun is almost always shining when TVA needs power the most. Solar energy systems produce power during 19 of 20 on-peak hours.
Somewhat more expensive tracking systems perform better than fixed-axis systems. While we expected to see this result, the actual impact was surprising. You can see the details in our Tennessee Valley Utility-Scale Solar Assessment.
Aggregating the “Top 10” sites together results in better performance than cherry picking the single “best” site. That’s because on some days, even the best site might significantly under-perform the “Top 10” group.
Siting matters most for optimizing when solar power produces, not how much. There is less variation from site to site when it comes to solar power production, but in terms of being dependable, our “Top 10” sites were “the best,” and significantly out performed “the rest.”
Below, you can see which sites made our “Top 10” list, listed alphabetically.
One of the two or three best sites for solar power in the Tennessee Valley Authority region is Oxford, Mississippi. Seems like the engineers at Ole Miss might already know about that, check out this 2011 video of a solar panel installation that’s in a bright spot!
“Top 10” Sites for Solar Power in the Tennessee Valley Authority: Dependable On-Peak Capacity Factor
|“Top 10” Plant Sites||Fixed-Axis||Tracking System|
|Caledonia CC Plant, MS||39.97 %||52.97 %|
|Gleason CT Plant, TN||43.44 %||55.01 %|
|Lagoon Creek CT-CC Plant, TN||41.06 %||52.20 %|
|Magnolia Plant CC, MS||40.25 %||52.75 %|
|Murray, KY||42.55 %||55.06 %|
|Muscle Shoals, AL||42.27 %||55.55 %|
|Oxford, MS||42.66 %||55.61 %|
|Philadelphia, MS||37.04 %||47.39 %|
|Starkville, MS||37.04 %||52.04 %|
|Tupelo, MS||43.65 %||55.53 %|
Dependable On-Peak Capacity Factor: This is a technical calculation, basically the amount of capacity that the utility can “rely” on when the system is peaking. No utility generator is 100% reliable, and each has its pros and cons. For example, high temperatures often result in thermal generators (like coal and nuclear) being reduced in output due to high temperature “cooling” water. A 50% dependable on-peak capacity factor means that the utility can be fairly certain that at least 50% of the rated output of the solar panel will be delivered during an on-peak hour.
“Top 10” sites: Out of our 26 systems that we studied, we selected the ten sites that had the best all-around performance based on several measures. This was somewhat arbitrary, and solar developers might find even better sites in places we didn’t look. Our study was really intended to understand how many sites needed to be considered in order to properly evaluate solar against other power resources. And like any technology, it makes sense to pick the best options when evaluating how to provide power reliably and cost-effectively.