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Data Acquisition

Is my Unique Solar Site suitable for a drone inspection?

By September 1, 2020November 22nd, 2023No Comments

Do you have an unusual or complex solar site that needs an inspection, but aren’t sure it is possible? Maybe it is a floating site or you have thin-film panels, can you still get a drone inspection and capture accurate aerial data for analysis and reporting? Check out some of the unique surveys that Sitemark has performed and discover if we can help with your particular site as well.

Solar Site Types

Ground-based: While ground-based panels may seem the most clear-cut and simple of solar installations, they, too, can have issues with inspections. For example, given the land space they consume, they are often used in remote or hard-to-access areas. These areas may also exist in harsh conditions, such as deserts or mountains. Also, they can be ideal for very large solar sites in such areas where land is usually less costly and less populated. These sites can be so large that they are impossible to check manually, i.e., the next inspection will be required when an inspection is completed. All of these situations make them ideal for drone inspections.

Roof-based: Popular in urban areas and excellent use of unfeasible space, rooftop installations have ample benefits. However, one of their cons is the difficulty of access and therefore, inspection. This location also presents a concern for the safety of inspection personnel. All of these issues are resolved with a drone inspection. While there can be more restrictions in urban areas for flying drones, Sitemark assists by providing an approved drone operator if needed. In addition to the solar panels, the drone inspection also identifies other problems rooftop concerns, such as thermal leakage.

Floating: These are the same PV panels used for traditional terrestrial systems that float on water bodies allowing solar power to be generated by the solar irradiance that would otherwise strike bodies of water. One of the most beneficial aspects comes from placing them on bodies of water that were previously unused or even unusable. These are the aquatic equivalent of brownfields: water that is man-made (meaning ecosystem disruption is less), inland, and calm. But the downside is that any installation, maintenance, and inspection of solar panels have added costs and complexities when they must be performed on the water. Since you can’t walk alongside the panels for a hand-held, manual inspection, here again, a drone inspection is truly the best, if not only, practical inspection option.

Singleaxis trackersA single-axis tracker moves the panels on one axis of movement, usually aligned with north and south. This system is designed to maximize solar energy collection throughout the year. Single-axis trackers are the most common tracking systems installed today. Although dual-axis trackers can increase total energy production by 5-10% above a single-axis tracker, single-axis trackers are more cost-effective and reliable. But while they are superior for PV productivity, they are tricky to inspect. The complexity lies in the fact that the panels move. This poses operational issues at the time of flying: the orientation of the trackers has to be taken into account by the pilot. At Sitemark, we have clear guidelines for the pilots to ensure the data acquisition process is smooth and to help tackle the complexity.

Dualaxis trackersA dual-axis tracker allows your panels to move on two axes, aligned along both the vertical axis and horizontal axis. This system is designed to maximize your solar energy collection throughout the year. It can track seasonal variations in the sun’s height and normal daily motion. As with the single-axis, the intricacy of the inspection is due to the moving panels and complex geometric structure, both of which are a challenge for traditional photogrammetry-based drone solutions. At Sitemark, we have developed a unique process to deliver a high-quality orthomosaic of your double-axis site, allowing you to benefit from a large view of your site and verify the analytics we deliver.

Solar Panel Technologies:

Mono/PolycrystallineBoth monocrystalline and polycrystalline solar panels have cells made of silicon wafers. Monocrystalline solar cells are more efficient because they are cut from a single silicon source. Polycrystalline solar cells are blended from multiple silicon sources and are slightly less efficient. These are the most common type of panel structure and do not present any unusual difficulties for inspection.

Thinfilm: Thin-film solar panels are made with solar cells with light-absorbing layers about 350 times smaller than a standard silicon panel. Because of their narrow design and the efficient semiconductor built into them, thin-film solar cells are the lightest PV cell available while maintaining strong durability. Efficiency has been the ultimate deciding factor that has prevented thin-film panels from gaining a foothold in the residential PV market. Whereas today’s standard silicon PV panels will have somewhere in the range of 15-20% efficiency, thin-film panels will likely hold a median closer to 11-13%, which can significantly impact your system’s physical size and electricity output. Thin-film must be installed on larger areas to accommodate the increased amount of space necessary for the system. For inspection purposes, these panels do not provide any particular inspection obstacles except that fewer types of anomalies can appear.

BifacialA bifacial solar panel is double-sided. These panels absorb sunlight from the front and rear sides via a transparent back sheet. The challenge with bifacial has always been the unpredictability of the power output because it’s dependent upon the substrate behind the modules, e.g., a white commercial roof, a dark comp shingle, grass, gravel, etc. Therefore, it is hard to model what the module will produce. It is impossible to inspect the underside of a panel for inspection purposes, only the front that is exposed to the drone camera’s view.

Split-cell: Split-cell technology is a new cell architecture that increases voltage by halving the size of the silicon chips. By cutting the standard cell in half and bus-barring it, they have the advantage of increasing efficiency and lowering the voltage and operating temperature. These last two benefits increase module longevity through decades of thermal cycling, eliminating hot spots. Also, split cell panels are stronger than traditional modules.

You have many options available to you as a solar site stakeholder, and we understand your primary goal is to maximize productivity no matter what your choice of solar panel technology or site location. Keep in mind that Sitemark’s Fuse platform is highly flexible and supports all of the variables discussed above. But even if your unusual panel or site is not listed here, please contact us with your questions or for advice as we love a challenge 😀.