Harnessing the power of the sun is certainly not a new concept. What is new is the large number of solar powered facilities being built across the country thanks to recent declines in the cost of solar panels and federal incentives for this energy source. Industry procedures, however, are not standardized and are constantly changing.
While many different approaches have been used in the rush to build these facilities, Terracon took the lead by creating standards for solar panel foundation design and testing which has helped clients reduce costs while improving the quality, safety, and efficiency of the foundations.
Solar panel foundations are typically anchored to resist “pull out,” similar to an umbrella on a windy day. Driven steel piles are the most common method of anchoring foundations. To determine foundation capacity in the most precise and direct way, a full-scale pile load testing process is used by most in the industry. Although widely accepted, Terracon recognized an opportunity to take this process one step further.
With a tradition of producing defensible work without compromising quality, Terracon established a dedicated group of energy sector professionals and regional solar practitioners to provide companywide support to clients. To begin the process of standardizing pile load testing, the team designed and built a tripod system which exceeds the American Society for Testing and Materials (ASTM) specifcations for deep foundation load testing. It became Terracon’s company standard and is being adopted by others in the industry.
Always working to exceed expectations, Terracon improved upon the tripod system by developing a more portable and less expensive load frame which greatly increased load-test productivity and reduced materials costs. Adding a laboratory-precision data acquisition system improved test accuracy and more fully described the application behavior. This doubled the number of tests practitioners can perform by simultaneously recording data from multiple instruments several times a second.
One client has already seen the benefits of these improvements. Earlier this year, Strata Solar set an aggressive schedule to complete a number of utility-scale solar farms in central and eastern North Carolina before the end of the year. By using Terracon’s enhanced driven steel piles testing process, hundreds of full-scale load tests were performed at project sites in the first six months. The projects are currently on schedule and will create enough energy to meet the needs of approximately 20,000 homes per year when complete. The improved efficiency allowed for rapid testing and turnaround of results without compromising quality or safety.
Terracon seeks other opportunities to design site specific load test programs to obtain better value per test based on use of specialty geotechnical subsurface investigation techniques. These include cone penetration testing (CPT) and dilatometer modulus testing (DMT). The experience of performing hundreds of pile load tests at locations adjacent to specialty in-situ testing has allowed for more accurate prediction of pile capacities. With these results, research and work with specialty testing will likely reduce the number of full-scale load tests per site in the future.
Terracon continues to be a leader in the solar industry and has become an expert resource for these projects. With local expertise, a large national footprint, continued process improvement developments, and superior client service, Terracon will continue to provide innovative solutions for the solar industry.