Site terrain is often a challenging hurdle in utility-scale photovoltaic (PV) solar projects. As the adoption of solar power soars, ideal, flat sites are drying up, particularly in developed markets such as the United States.
As this “claiming” of ideal sites continues, developers will see a rise in project placement in less-than-optimal locations that require more design forethought and, nearly always, some amount of land grading to optimize power yield.
Grading to overcome challenging site terrain can bring oversized expenses and time investment, potentially hamstringing projects before they even begin.
With thoughtful design and leveraging single-axis trackers with high tolerances for challenging, undulating site terrain, excessive grading can be avoided.
Over-Grading Costs You Money and Time
Site grading adds a costly and time-consuming step to an already complex timeline. Worse, “over-grading,” so to speak, can result from choosing a sub-optimal tracker design that can unnecessarily drive-up project costs.
The time spent grading may even overshadow hard costs, particularly when research needs to be completed regarding the potential environmental impact of site alteration.
A recent study from the University of Michigan of select solar projects in California put some numbers to the average grading needs of a utility-scale PV plant project. Of the six projects studied, none needed fewer than 1,000,000 cubic yards of grading work completed, and the highest required upward of 8,000,000 cubic yards.
1,000,000 cubic yards of soil is the equivalent of 972,000 tons. 8,000,000 cubic yards of soil is approximately 7,776,000 tons. Project Managers faced with a civil engineering effort of this scale can do the math in their heads on the high cost of site grading.
To put one project’s grading effort into a fantastic visual, the University of Michigan study details that if one project’s substantial pre-build earthwork “were placed onto a football field, the mound of soil would be over a mile in height.”
Let’s look at a real-world project example. A recent Array Technologies project spotlights the value a tracker with high terrain flexibility can offer. A decentralized tracker was estimated by civil engineers to require the following grading requirements for their tracker:
- Cut – 637,000 Cubic Yards
- Fill – 251,000 Cubic Yards
- Net – 386,000 Cubic Yards of Cut
Array’s centralized and flexibly linked DuraTrack single-axis tracker was able to eliminate a vast amount of this grading requirement. Here was the estimate of the grading effort from Array’s engineers, using DuraTrack:
- Cut – 243,000 Cubic Yards
- Fill – 114,000 Cubic Yards
- Net – 129,000 Cubic Yards of Cut
The decentralized tracker required 160% more grading. This additional effort would have required 25,700 additional dump truck trips to move the cut on site or to a distant disposal site.
The reason? DuraTrack’s extreme terrain flexibility allows for a more precise analysis of how the plant’s energy production will be affected by grading – calculating when “over-grading” is unnecessary.
The bottom line is this – while some amount of grading is almost certainly unavoidable, adding more grading than necessary to a project significantly affects the project budget and timeline.
Terrain Flexible Single-Axis Trackers Eliminate the Grading Roadblock
When assessing a potential utility-scale PV site, it is essential to get your tracker vendor engaged as early as possible, as the foundation of power plant tracker selection is key to adapting to terrain challenges.
By using flexible, single-axis solar trackers designed to handle challenging site terrain, utility-scale PV plants can optimize power production while mitigating the expensive process of grading a site to produce more ideal conditions.
This translates directly into profitability for PV plants, and terrain flexibility empowers developers to more easily optimize layouts to increase energy production without significant disruption.
Array Technologies DuraTrack® HZ v3 delivers terrain flexibility and optimized production yield in several ways:
- Power density is optimized by eliminating “module dead spaces” caused by motors and bearings, minimizing the gap between modules and allowing for an increase in the area where panels can be mounted.
- Linked, articulated drivelines accommodate different site slopes without requiring grading to make a site flatter.
- Engineered simplicity – fewer moving parts – reduces overall component failure risk and increases reliability over the 30+ year lifespan of a modern PV power plant, lowering overall cost of ownership.
DuraTrack® is flexible enough to handle uneven terrain, eliminating the need for grading, helping contractors, engineers, EPCs, and asset owners increase project profitability and long-term value.
Combining DuraTrack with Array’s software solution, SmarTrack™ aids in navigating complex terrain, allowing for optimal backtracking, low-light module adjustments, and advanced machine learning related to row height differences and uneven site terrain.
Flexibly Linked Single-axis Solar Trackers: The Best of Both Worlds
Improved utility-scale PV power plant design, and improved bankability, results from finding the right balance of equipment and grading. When that balance is struck, even non-ideal sites can produce tremendous results.
Finding the sweet spot where both grading and foundation design are optimized is, in some cases, a million-dollar question – and it is one that is often made without proper due diligence, based on industry myths, or using site data from previous projects that may be inappropriate.
An often-misunderstood concept is that centralized solar tracking solutions aren’t flexible or able to contour with natural undulations in the land. Array’s elegant tracking solution provides harmony between the flexibly linked single-axis architecture while relying on the natural savings that come from reduced parts when compared to a decentralized tracking solution.
Array engineers help clients optimize a plant design that answers the challenge of finding the right – and most cost-effective – balance between tracker layout vs. grading.
How does Array help EPCs and developers answer the grading question? Array trackers offer extremely high tolerances for terrain flexibility. DuraTrack allows for up to 40% grades in the east-west direction and 26% in the north-south direction. Additionally, post reveal heights are, from a design perspective, practically limitless, and typically determined by budget and wind requirements. This flexibility allows project engineers and designers to more accurately optimize tracker and grading costs.
To learn more about how we can help you optimize your design regardless of how challenging the terrain, contact us today.
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