Innovations that drive improvements on project sites often are the result of collaboration between field engineers and construction professionals who have the closest view of specific daily challenges. An integrated engineer-procure-construct (EPC) project delivery method can be the catalyst for such innovations because it removes barriers to collaboration that can sometimes be present in other contracting methodologies.
Integrated EPC has a proven track record for improved safety, quality, cost control and schedule certainty. Now, it is also emerging as a means to drive innovations in digital technology applications applied to work on solar project sites.
Greater Efficiency on Solar Installations
A series of custom technology applications developed specifically for the repetitive tasks required to install thousands of photovoltaic (PV) panels at utility-scale solar facilities is creating a continuous learning environment for engineers and construction professionals working on these projects.
For solar project sites that can span hundreds of acres, the engineering team starts with a geospatial survey of the topography. That data is then loaded into an AutoCAD file to build a detailed layout that includes the precise locations of each pile that must be driven into the ground.
From there, a CSV (comma-separated values) file is exported from AutoCAD into a custom application developed inhouse by Burns & McDonnell that calculates the precise height that each pile will extend above the ground surface. The tool then calculates whether each pile height will be within specified tolerances of the tracker manufacturer. If there are locations where the application shows that the piles would extend higher or lower than specified ranges, instructions for site grading would then be generated. Those instructions specify the required surface elevations so that piles can be installed at necessary heights.
The digital application also maps out the locations of trenches that must be dug on the project site for underground cabling or other equipment. Precise dig locations are digitally tracked so that excavation contractors avoid spots where piles will be located.
Once site work is completed and the tool is run again to verify correct tolerances, a new CSV file is uploaded into a Vermeer PD10 pile driver unit using a GPS system. This data is automatically uploaded as instructions and transforms the pile driver unit into a totally integrated piece of construction equipment. Engineers look at a digital representation of each pile after it is installed to verify that as-built conditions match the anticipated as-designed conditions.
Once piles are installed to correct depths, the pile reveal elevation is analyzed to set a precise height for installation of a saddle bracket that will be bolted onto the top of the pile, connecting with the tracker unit. Tracker units may be up to 350 feet long, spanning 15 to 20 piles, so it is critical that the brackets are installed at precise heights to prevent binding and premature failure of moving components in each tracker.
No More Lasers and String Lines
Utilizing digital instructions to set the bracket heights eliminates the need for lasers on each row to set the bracket heights on each pile. These tools are delivering significant improvements in quality, with fewer than 1% of piles requiring rework on most sites during pile installation, and fewer than 0.5% of saddle brackets being reworked. Not only does this shave time from the schedule, it also saves costs because fewer people are needed on-site.
The proprietary technology is paying off in major improvements in accuracy of placements and depths of the solar piles. It also is creating more efficiency in scheduling equipment deliveries and times when personnel are needed on the project site.
Perhaps the greatest benefit is much improved communication. Empowered by the flexibility of EPC contracting, the construction and engineering teams continue to collaborate and develop innovative ideas that are constantly improving project deliverables. The key is relying on what the data is saying, enabling continuing analysis and adjustments in an ongoing iterative process.
As installed costs of solar power drop, utility-scale solar projects are being built at an accelerating pace. Upfront planning and early integration of engineering and construction can head off challenges in an increasingly volatile market.
