Since the creation of the solar investment tax credit in 2005, solar has expanded rapidly to over 14,000 MW of installed capacity in the U.S. Because of the age of these assets — and the thousands of megawatts of energy they create — plants are entering a twilight phase of their life cycle, in which the ability of the plant owner to effectively evaluate the present and future value of their assets becomes critical.

Considering a variety of factors — such as operational assessments of each plant’s future state over the next five years, operations and maintenance costs, and the competitive renewable market — owners are beginning to wonder about the value of their facilities. Where can I most effectively spend operations and maintenance budget? What efficiencies can technology bring to site operations and valuation? Should I sell it or keep my asset?

This is where a full-site inspection and consulting services can be advantageous. By looking closely at all components of a solar generation plant, an owner can get a high-level view of the plant’s overall state and costs for improvements needed for the plant to remain cost-efficient and relevant into the future. Adding an unmanned aerial systems (UAS) infrared imagery inspection to find faults in photovoltaic (PV) panels can provide added value.

How It Works

Locating the cause of losses at a plant can be difficult for an owner without such an inspection, especially if asset data is only being collected at certain points in the string of modules, such as at an inverter. For example, an owner might have 30 modules in a single string while 20 such strings might be interconnected through a single inverter. That would leave 600 total modules without a direct source of data to indicate the current state of those assets.

At its simplest, using UAS to inspect PV panels can solve for this issue by determining specific areas where there is potential loss of solar production, as well as finding potential causes of that loss. Inspecting sites in this way captures infrared imagery, revealing hot spots on modules along these strings. Such spots appearing on a panel indicate dissipating heat, which means a loss of energy. This can be caused by several things, including vegetation shading, bird guano and faulty circuitry.

Data collected during the UAS flight is processed and pieced together to form a map that displays any hot spots throughout a plant while providing potential reasoning for these trouble spots. This detailed visibility provides invaluable information to maintenance crews, who are then responsible for going out into the field to address identified issues.

Value vs. Expense

As with anything in a business, owners must be able to validate the costs of these inspections against the returned value of remedying the problems they identify.

For UAS inspections, the expense depends on the size of the site compared to the overall losses an owner is experiencing. It could be difficult to see a return on investment for smaller generation plants, for example, as costs of deploying a team, flying the UAS and processing the data will be higher than the returned revenue created by repairs.

Economies of scale play a role in determining when you begin flying the UAS as a part of solar site inspection. Production loss, plant size, site geography and other factors all contribute to determining whether or not to add UAS to the overall plant inspection in order to recuperate costs of the service.

This is, of course, a situation-by-situation scenario. What an owner is really comparing is the cost of work-hours for doing inspections on foot as opposed to using a UAS. Many owners may already be collecting the operational data that will allow them to perform procedures to show degradation of certain areas in a string, thus enabling them to perform a low-level inspection of modules on their own.

A Holistic Inspection

An overall plant inspection will consider historical operational data to build a complete view of the facility, offering a plan that presents a path forward for the facility. The use of UAS to inspect solar panels can be part of this holistic approach — including physical inspection and fiscal plant valuation consulting — to offer a more holistic view into an asset’s fiscal potential.

Working alongside a partner who can provide holistic plant inspection services is the most effective way to get real value from the data collected during a UAS flight. Proper interpretation and management of this data will provide solutions and design remedies that more directly impact plant value and revenues.

As plants continue to age, inspections become an increasingly important part of running an effective business. Getting the most out of an inspection could mean adding a UAS flight to gather infrared data but understanding the ins and outs will help owners get the most value out of a holistic inspection approach.


Want to learn more about how solar assets age over time? Check out our analysis for predicting long-term performance degradation of PV power plants.

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Jonathan Leffert, PE, is a managing director in California for 1898 & Co., part of Burns & McDonnell. His team leads clients through business transformation by developing innovative solutions and providing high-value technology, management and security consulting services in present-state and emerging technologies. Their initiatives include business intelligence and visualization, enterprise system integration and software development, technology enablement, grid modernization, transportation electrification, cybersecurity and smart cities. Jonathan has a Bachelor of Science in electrical engineering from Kansas State University.