According to Solar Power Europe, the association representing the European solar sector, expectations around the growth of solar in Europe remain strong. In a recent report(1), the organisation concluded that newly installed solar power in the European Union increased by 11% to 18.2 GW in 2020. And market analysis leads to the conclusion that 2020 will be followed by 4 years characterised by stronger demands, with 22.4 GW in installations for 2021 and new annual additions of 27.4 GW in 2022. Though the growth rate will slightly decrease to 13% in 2023 and 14% in 2024, solar deployment will be at 30.8 GW in 2023 and 35.1 GW in 2024. In total the cumulative installed capacity increased by 15% to 137.2 GW.
In comparison, the US Solar Market Insight Report 2020 Q4, reported 88.9 GWdc in operation.(2) Further, the US report notes that at the current growth rate, that number is likely to reach 100 GWdc by 2023 and exceed 250 GWdc by 2030 — assuming sufficient investment is available and the construction community can keep up. While investment is for another discussion, utility solar farm construction productivity and efficiency is undergoing an impressive technological transformation.
To facilitate growing demand and meet ever tighter timelines, engineering contractors working on solar farms are adopting proven construction technology capabilities from other applications to optimize their workflows. 3D machine-guidance and machine-control systems on graders, excavators and dozers are for instance already helping these contractors improve productivity, accuracy and safety. Steering Control for dozers automatically controls the machine to follow any horizontal alignment such as a back of a curb, breakline, roadway centerline or bottom of slope, without operator assistance. The augmented reality functionality shows the operator 3D models with cut/fill information, slope data and other bench points and reference points on an in-cab display. So they can make sure they work exactly to the plans and specifications. By using similar systems in utility solar farm construction, specifically on piling machines, these machines turn from purely functional tools into data gathering tools driving the value of data across the construction continuum.
The 3D Advantage
The nature of utility scale solar farm construction is repetitive — conduct a site survey, develop a plan, install piles, posts and panels, and repeat. However, the process requires consistency and accuracy to ensure the panels can move freely, sit at the right height for optimal visibility and minimize wasted space. Accuracy can also be an issue. Pile rework to correct misalignments can add up to significant cost and time.
Over the last 5 years, leading contractors have begun to test and deploy more automated 3D-enabled pile driving approaches with impressive results. For instance, several years ago, TerraSmart, a US based utility scale solar solution provider started working with five drill rigs equipped with the full 3D Trimble Drilling System as a way to install thousands of solar panel rack ground screws in rocky ground with speed and accuracy.
In just four months crews drilled more than 62,000 holes and completed the rock drilling portion of the process 50% faster with the Trimble-enabled rigs than using traditional methods. The team has also improved the accuracy of the drilling over time, fine tuning the entire system to work with ground conditions, allowing crews to maintain holes within ½-inch tolerance.
Further, the TerraSmart team using a Robotic Total Station, set the mounting legs to match the elevation change of the ground. Using this system, TerraSmart crews were able to adhere to the height, placement and 1% angle break between leg tolerances required by the general contractor.
On a more recent project, McCarthy Building Companies used Trimble’s Piling System on a GAYK Hydraulic Ram piling machine to support a 400-acre utility-scale solar field project in Millington, Tennessee. The team used software to combine geospatial survey data into CAD drawings that can be read by the piling system. The pile plan included pile length, elevation, required embedment depth and alignments. Once exported to the piling system, the plans were visible by the operators from the on-board displays to facilitate drilling. Operators were also able to view completed piles compared against planned piles in both 2D and 3D views.
Using this 3D machine-guided approach, the contractor reduced the labor required for prep and pile installation by more than 50%, reduced the crew required from 12 people to a crew of three or four people. Notably, crews were also able to install piles about 10% faster but with greater accuracy, keeping pace with an aggressive schedule of three months, even with delays due to rain, snow, extreme heat or cold. The engineering team noticed that overall, piles were placed more accurately as compared to manual methods. Lessons learned from this one project are setting the foundation for future work processes on additional solar projects.
Connected and Controlled
Along with industry applications, 3D guidance features and functionality continue to expand as well. This creates opportunities for greater efficiency and accuracy. For instance, 3D guided solutions provide mast tilt and drill depth control with auto-stop on the target elevation so that piles are drilled to the exact depth specified.
3D guided piling solutions are designed to withstand shock and vibration of drilling machines. For ease-of-use these systems offer large touch screens and icons, with clearly visible screens, even in bright sunlight, guiding users through streamlined workflows. Connectivity is also particularly important. As solar scale utility farms are often in remote locations, integrated office and field solutions are a necessity for efficiency.
The value of 3D guided piling on utility scale PV sites has been proven, and will be an essential part of the process as contractors strive to meet the anticipated additional developments in the next five years.