Your Ultimate Guide to Drone Thermography and I-V Curve Tracing

When building and maintaining solar farms, drone thermography is increasingly utilized to inspect solar panels—saving time and labor. The manual, industry-standard method of inspecting solar panels, known as I-V curve tracing, is known for being cost- and labor-intensive, making drone thermography a more appealing option for many.

To understand the pros and cons, you need to understand the structure of a photovoltaic system. PV systems are built with the smallest unit first—most often a solar cell. Cells are put together in rows to form panels, and when panels are put together, they form a string. Put enough of them together, and you get an array. 

With photovoltaic systems often being composed of multiple arrays, it’s essential to conduct regular inspections of the solar arrays and components that support the system. It’s also imperative to keep up with maintenance to limit system degradation. 

In this article, you’ll learn the differences between drone thermography, and I-V curve tracing, their pros and cons, and which inspection method best suits your solar project. 

What is Drone Thermography?

When a PV system requires inspection, thermography drones offer unique value: These drones are equipped with a thermal camera to read for anomalies and measure temperature. Drone thermal imaging picks up infrared—a benefit that can detect disparities in heat and, by extension, power production.

With the assistance of location data, aerial thermography drones pinpoint potential problems in PV modules. Inspectors can examine the entire area, saving time, money, and labor. 

What is IV Tracing?

In comparison, I-V curve tracing is the industry standard for inspecting PV panels. As an equation, I-V curve tracing examines the current (I) and voltage (V) to get a read on the power output of a PV system. 

Similarly to aerial thermography, curve tracing, also called manual electric testing in the solar industry, pinpoints potential issues, such as reduced currency and voltage. This method of inspecting PV systems requires a technician and a testing device to methodically test individual panels—a process that can be time- and labor-intensive.

When inspectors use this method, anomalies are detected when the I-V curve is generated and read by the technician. Additional testing may be required to find the specific panel causing issues.

How Are Drone Thermography and I-V Curve Tracing Different?

Drone thermography and I-V curve tracing differ in their delivery. Aerial thermography is conducted with drone and location information, while I-V curve tracing requires much more time. The latter has been the industry standard for some time and highlights that while these methods are different, each has its own pros and cons. 

Pros of Drone Thermography 

As well as being more cost- and labor-effective, drone technology, equipped with a thermal camera, can detect anomalies on a microscopic level. Infrared thermography is also favored for the time it saves in collecting data: It takes roughly 10 minutes to measure a megawatt (MW) of power. (For larger arrays, this will certainly take more time.)

Arrays inspected with a drone are required to stay online during the process, eliminating downtime. This way, the thermal imaging camera reads temperature differences, and the array is able to continue producing power. A drone can also inspect an entire array at one time. 

Drone operators also benefit from safety as an added bonus, as the operator can conduct the inspection from a safe location—reducing the risk of heat exhaustion and other concerns. Drones can also be used in roof inspections and power line assessments. 

Aerial Thermography Cons

To ensure accurate data, drone pilots need the Federal Aviation Administration’s (FAA) Part 107 license, which requires passing multiple tests. Operating a drone also requires awareness of local aerial restrictions, which are overseen by the FAA. 

Pros of I-V Curve Tracing

One of the benefits of I-V curve tracing is the technician requirement. Since the technician works with electrical components, those conducting I-V tracing must be licensed electrical workers. The added expertise benefits the quality of the work and overall assessment.

Some of the other benefits of industry-standard PV inspection include:

• Reduced risk at startup
• Comprehensive baselines for performance
• Detecting panel weaknesses such as soiling and series resistance
• Among other benefits

Cons of I-V Curve Tracing

The primary downside of I-V curve tracing is needing to have a technician on site, rather than stationed in a remote, safe location. The same technician also takes 3 to 5 hours to measure a MW of power. While the data can be analyzed instantly, it can take days to assess the data from a large array. 

The necessity of a technician onsite also means a higher risk of error in interpreting results. And though personal protective equipment (PPE) is a benefit in protecting the technician, heavy PPE can cause heat exhaustion and other problems. I-V curve tracing also requires a level of irradiance of 400 watts per square meter, meaning weather can also be a restriction.

If the data requires further analysis, another technician will need to read it, potentially adding to the costs of the project. 

Depending on your budget, the cost of I-V curve tracing may also be a concern: The longer an inspection project takes—if there are additional inspections needed, for example—the more labor and time it can take.

Which Is the Better Option?

As is evident from the above, there is no true one-size-fits-all best solution for your inspection project. While having the added expertise of a licensed electrician can be a benefit, larger arrays may require faster data gathering with aerial infrared cameras and infrared images. 

Whether you choose drone thermography or I-V curve tracing, inspection data needs to be easily accessible and manageable. 60H makes your data actionable. 

60Hertz Energy’s computerized maintenance management system (CMMS) offers specific fields for streamlined data entry, an offline mode, and multiple language options for ease of reading. Contact 60Hertz Energy to see how our premier CMMS simplifies data storage and access for inspection projects.