Use of drones in the solar Industry

Unmanned Aerial Vehicles (UAVs), commonly known these days as drones, have been with us for more than a century. The earliest example that we might recognise as a drone appeared in 1916, a radio-controlled pilotless aircraft developed for military use. Drones would continue to find military applications throughout the 20th century.

The breakthrough came when the Parrot AR Drone, a smartphone-controlled quadcopter for consumers, was introduced at the Consumer Electronics Show in Las Vegas in 2010. Technology improvements came thick and fast, and today the quadcopter drone is a common sight around the world, from a $20 toy to sophisticated professional craft. Goldman Sachs forecasts the total drone market size to be worth $100 billion. Commercially, they are proving their value across a wide range of industries from construction to agriculture, mining to oil and gas – and the solar power sector. 

Solar farms are getting bigger every year: the Mohammed bin Rashid Al Maktoum Solar Park in Dubai, for example, is one of the largest solar parks in the world, spanning 77 square kilometres. The challenge of designing, constructing, monitoring, cleaning and maintaining a solar park of this size is simply mind-boggling. However, drones are flying to the rescue to help massive solar parks function at optimal levels. Dubai Electricity and Water Authority (DEWA), which owns and operates MBR Solar Park, is using advanced drones to support Dubai’s growing infrastructure. Its drones embrace state-of-the-art technologies such as high-definition cameras that are equipped with night-vision and laser technologies, GPS sensors that can measure pressure, height, magnetic fields, and use ultrasound scanning.

Pre-construction phase

Let’s look at how drones fit into the solar framework. Before construction begins on a ground-mounted solar system, the engineers need to understand the condition of the proposed site. Today, they can use drones to survey the topography to help assess whether they need to do any preparatory earthwork. Drones can use the latest cameras to generate contour maps, digital surface models, and even 3D models in a fraction of the time needed to do it on the ground in the traditional manner. The survey results allow designers to position the solar panels where they’ll get maximum sunlight. Even for a simple rooftop PV system, drones can accelerate the planning process by performing aerial surveys that are 75% faster than manual surveys.

Construction monitoring and commissioning

Once the construction of a PV system is underway, drones can be used to monitor progress by collecting aerial imagery at regular intervals, daily or weekly, to track changes and provide statistics on the project in real time. Overlaying drone images on the original plans can help identify any discrepancies, which can then be put right more easily and cheaply than later in the project.

Drones also play a role in the commissioning and asset transfer stages by checking that the installation is complete, safe and compliant with all safety requirements. Drone inspections can help spot installation issues such as defective modules, string outages, and inverter and combiner anomalies. Inspections at the commissioning stage can also provide documentation for future inspections, providing a baseline for the future.

Maintenance inspections

Drones really come into their own for routine solar maintenance inspections. There are traditionally conducted manually with handheld thermal cameras or using I-V curve tracing, which is the process of analysing the current-voltage characteristics of an electrical path. However, checking solar panels one by one with a handheld device is clearly a lengthy process in a large-scale park. I-V curve tracing can take 2-5 hours per megawatt (MW) for a group of technicians to inspect. In a large solar plant, that can be expensive. To save time, it’s tempting to check only a sample size of the site, but then you run the risk of missing faulty panels.

Drones equipped with infrared cameras provide a faster solution, flying over 1 MW of solar panels in just 10 minutes, a fraction of the time required for traditional methods. If the camera picks up excessive heat levels, for example, it indicates that a panel is damaged or defective. The images taken can be uploaded to a computer operating artificial intelligence software to scan for anomalies and defects. The diagnostic data can provide an accurate assessment of your solar plant’s health, and even offer a cost-benefit analysis on the improvements needed. A major benefit with drone inspection is that, unlike with manual I-V curve inspections, drones can inspect solar panels while they are still operating.

Drones also have an important role in inspecting the transmission lines that distribute solar energy from solar plants to outside areas. Manual transmission line inspections can be dangerous due to the high voltages involved and the height of the suspended lines.

Keeping the panels clean

One of the problems facing solar panels is loss of energy output due to a build-up of dust and dirt: the losses can be in the range of 20%-50%. Various robotic cleaners are available to sweep the panels, but now there’s a drone solution too that’s potentially very attractive in hard-to-access locations. In this application, the drone is kept inside a weatherproof dock close to the solar panels and is released to spray each panel with cleaning fluid. The system is designed to replace discharged batteries and replenish cleaning fluid automatically, allowing almost continuous operation.

From site mapping to construction monitoring, commissioning to data collection, maintenance to cleaning, drones are helping to deliver the full potential of the solar energy that will play such a significant role in all our futures.