Case Study: How Drone Surveying Facilitates Solar Plant Development

INDUSTRY: Renewable Energy // APPLICATION: Solar plant development // PAYLOAD/CAMERA: Phantom 4 Pro RTK // COUNTRY: South Africa

The Challenge:

Using reliable data to help meet tight deadlines while ensuring high accuracy from the digital design to the physical construction of solar panels.

GENERGY, a prominent solar company in South Africa, developed a 1.4MWp Photovoltaic (PV) solar power plant covering just under 2 hectares of land in the slopes of a mountainous region in the Western Cape.

This project marked the first phase of a two-phase development to meet an agricultural company's urgent demand for reliable electricity supply. The need arose from the company's goal to enhance production capabilities. The solar power plant, integral to the company’s operations, symbolises a proactive step towards improving operational efficiency and resilience amidst evolving energy demands; with winter approaching and the risk of seasonal rain, surveying the area and setting up the solar power plant before the rainy season was vital to avoid potential disruptions in electricity generation. Delays installing the solar power plant could result in significant revenue loss for the company.

To meet a tight deadline for site establishment, GENERGY chose aerial land surveying with drone data acquisition over traditional methods. Using high-resolution aerial imagery, this approach enables quicker data collection and, as a result, faster creation of required outputs such as accurate Digital Terrain Models (DTMs) and topographical maps. Given the sloping terrain, creating an accurate DTM was crucial for precisely designing and placing the solar plant and its components.

GENERGY partnered with us, IAS, a fully licensed drone company (UASOC) known for its professional drone and land surveying services. We focus on efficiency and effectiveness, empowering customers and driving meaningful change within tight deadlines. Our commitment to reliability and thoroughness ensures that tasks are completed with precision and care. Engaging IAS was crucial to meeting their project requirements within a strict timeline. We provided a comprehensive solution, offering expertise in two critical areas: design and construction.

Utilising IAS Expertise for Precision and Efficiency in Project Scope and Execution

During the design stage, IAS furnished the georeferenced DTM and topographical map crucial for positioning mounting systems and solar panels in the design process. Photogrammetry was able to generate accurate terrain data using aerial imagery. This method minimises the need for expensive equipment and extensive fieldwork, resulting in cost savings compared to traditional surveying methods.

The scope of work encompassed several key tasks, beginning with establishing Ground Control Points (GCPs) using GNSS technology (Figure 3). GCPs ensure precise geo-referencing, accuracy, reliability, and data usability. This precision allows for the exact design and placement of solar panels, enabling efficient power generation in the future.

While the GCPs were being placed and surveyed, the aerial survey using a Phantom 4 Pro RTK system was set up and started. Figure 4 above shows the setup of the DJI RTK unit and our pilot, Aiden Kerr. The RTK enables precise measurements in all axes: x, y, and z.? The drone communicates with the RTK unit to ensure that every image has accurate positioning GNSS metadata.

We spent about an hour on-site, where the drone surveyed for about 30 minutes around midday at an altitude of 100m, using terrain-follow and 3D crosshatch settings. These parameters obtained less than 3cm ground sample distance (GSD).?

Upon returning to the office, the aerial data and the GCPs were processed together using sophisticated software to ensure accuracy, reliability, and precision in the processing of the data (Figure 5). The geo-referenced DTM and topographical map (Figure 6) was subsequently created from this data, showing the GCPs, contours of the DTM at 0.50m intervals and other physical features such as roads.

The DTM and topographical map were shared with the engineers, who then accurately positioned the blueprint of the solar panels onto the data in CAD format (Figure 7). A precise and accurate DTM is indispensable for optimising solar panels' design, placement, and efficiency. It plays a crucial role in planning the placement of the panels for several reasons:

• Facilitates precise analysis of the topography to determine optimal sunlight exposure, shading, and accurate placement and orientation.
• Enables hydrological analysis to understand drainage and erosion around the solar plant.
• Supports efficient planning and utilisation of available land.
• It can aid in conducting environmental impact assessments.

Once the CAD overlay of the solar plant design was accurately completed, the map was returned to IAS, where we then extracted the real-world coordinates of the corner posts of each mounting structure of the solar panels. This step was pivotal in translating the digital blueprint into reality, and we further played a crucial role in translating this digital blueprint into reality in the construction phase.

Utilising our in-house professional land surveyor expertise and GNSS survey technology, we meticulously staked out the corner posts of the mounting structures on site (Figure 8). This meticulous approach ensured perfect alignment between the digital design and the physical infrastructure, enabling GENERGY engineers to accurately position their ramming machines for pile installation (Figure 9). Achieving a high level of accuracy and precision during the corner post positioning was facilitated by the use of GPS technology, including rover and base station. The deployment of the base station ensured precise staking out of posts, even on challenging terrain.

Achieving Precision and Success in Solar Plant Development

Despite time constraints, the crucial task of setting out the corner post positions of the mounting systems was executed with exceptional accuracy and efficiency. The mounting systems depicted in the image below (Figure 10) exhibit precise alignment, serving as a testament to the meticulous approach facilitated by aerial surveying.

The availability of comprehensive data is invaluable for future analysis and planning, ensuring that the data can be used over the next few years. A significant advantage of drone-based surveying, compared to ground-based methods, is the rapid collection of data, leading to faster project completion. Drones can cover large areas swiftly, gathering data in a fraction of the time required by traditional surveying teams. Additionally, drone surveying typically requires fewer labour and resources compared to traditional methods, often only necessitating a smaller team or even a single operator.

While not applicable in this case, aerial surveying excels in mapping remote or hard-to-reach areas that may pose challenges or safety concerns for ground-based surveyors. Aerial surveying provides detailed topographical data through high-resolution imagery, ensuring reliable and accurate data suitable for various engineering and planning applications. Moreover, drone-based surveys offer consistent data quality, contributing to enhanced accuracy. Drones maintain a steady altitude and speed during flights, resulting in uniform data quality throughout the surveyed area.

The takeaway

Aerial data played a crucial role in the initial stages of the project, where high-resolution imagery and accurate topographical maps empowered GENERGY’s engineers to optimise panel placement, layout, and orientation for maximum efficiency. The deployment of aerial surveying proved indispensable in providing GENERGY with precise data to navigate the early stages of their solar project with exceptional accuracy and reliability, all within strict deadlines. By significantly reducing the need for extensive manual surveying, drone technology streamlined the process, minimising site and data collection time and reducing the potential for human error, ultimately leading to superior project outcomes.

The project gains a valuable resource for informed decision-making and sustainable development practices by harnessing aerial surveying technology. This approach paves the way for continued success and responsible stewardship of the environment, ensuring that the project aligns with efficiency and environmental conservation principles.

About IAS

IAS (Pty) Ltd has operated since 2018 as a pioneer in aerial surveying for the solar EPC industry.? We have a team of GIS specialists and Professional Land Surveyors that produce accurate and cost-effective maps for engineers to be confident in constructing a solar plant design.?

Contact us for further information: [email protected] | 021 001 0449

Manager of Business Development: [email protected] | 083 269 6785

Professional Land Surveyor (PLS1441): [email protected] | 082 842 7822