Maintaining solar panels is a crucial element in ensuring optimal performance of photovoltaic (PV) systems throughout their lifespan. The most cost-effective and efficient method for inspecting solar panels is currently by using drones equipped with thermography technology.
However, it's important to determine how often PV systems should be inspected by drones. The most commonly used schedules for drone-based thermography inspections are quarterly, semi-annually, or annually. Nonetheless, it's worth noting that older PV systems require more frequent proactive maintenance inspections. This article examines the various factors that dictate the frequency of solar panel inspections and outlines the recommended best practices for keeping PV systems well-maintained using drone thermography.

Preventive Maintenance: Inspection Schedules for Aerial Thermography
Typically, preventive maintenance plans that involve aerial thermography inspections are conducted once a year. During these inspections, a range of issues that might potentially affect the functioning of solar panels are checked for.
When assessing individual components of a solar installation, recommended inspection schedules may vary depending on the type of equipment and the installation. They can range from monthly, quarterly, yearly, to semi-annually. Aerial drone inspections are instrumental in determining an appropriate inspection schedule, and a preventive maintenance plan that incorporates aerial inspection solutions would cover a range of items such as:
PV arrays
Electrical equipment
Mounting structures
Fencing
Shading areas
Trackers
Vegetation
Animal damage
Erosion
Corrosion
Discoloured panels
During a preventive maintenance inspection, it is common to perform string-level open-circuit voltage, DC operating current tests, and I-V curve traces on strings. These manual tests have to be performed by hand, which results in very time-consuming and costly procedures. However, since the introduction of aerial inspections these types of manual preventive maintenance practices are being increasingly phased out by O&M and electrical contractors.
By using drones to perform these inspections, businesses can save time and reduce costs while still maintaining the highest level of performance from their solar panel systems.
Measuring System Performance During Commissioning
Evaluating the performance of a new solar PV site during commissioning is a crucial measure to ensure the entire system functions at optimal performance levels.
The commissioning of a solar site involves verifying that a new solar PV system has been installed, configured, and operates in accordance with the manufacturer's specifications, relevant regulations, customer requirements, and compliance criteria set by the International Electrotechnical Commission (IEC). To confirm that the system operates effectively and that all components perform as anticipated, a drone pilot often performs various tests and checks.
Issues with PV systems are often discovered during the commissioning phase when the equipment is new and untested under normal operating conditions. Thus, it's essential to properly document the commissioning and testing stage for several reasons:
Compliance - Regulatory bodies frequently require adequate documentation to verify that the system complies with local regulations, codes, and standards.
Warranty - Many solar panel system components are still under warranty during commissioning, and manufacturers may require documentation of commissioning and testing to honour warranty claims.
Performance Monitoring - Documentation of commissioning and testing can be utilized to establish a baseline for the system's performance and track performance over time. This aids in determining if the system output matches the manufacturer's specified production levels.
Maintenance and Troubleshooting - Maintenance crews can use documentation to determine how the system was initially configured and what tests were conducted, aiding in the quicker identification of the root cause of any issues.
Future Reference - After the inspection, the drone's collected data is analyzed and used to create a comprehensive report, including any identified issues and recommendations for repairs or adjustments. This report serves as a reference point for future evaluations.
Recommended Inspection Frequency After Site Commissioning
It is suggested that inspections be conducted every 3-6 months during the first year after the site has been commissioned to ensure that the solar panel system is functioning correctly. This will allow for monitoring of the system's performance over time, identifying patterns in issues, and making any necessary maintenance schedule adjustments. By regularly monitoring and adjusting the system's performance, businesses can ensure that their solar panel system operates at its best for the duration of its life.
Factors that Determine Inspection Frequency
Finding the appropriate inspection frequency for solar PV systems or solar farms using drone inspections is essential for maintaining the system. The inspection frequency is determined by various factors that affect each site differently. These five factors are particularly important:
Age of the System: The age of the system is a crucial factor in determining inspection frequency. Newer systems typically require fewer inspections than older systems, as they are less likely to develop issues over time. As the system ages, the likelihood of problems arising increases, so the frequency of inspections should increase accordingly. Historical drone data from a commissioning inspection conducted when the site began operations can be used to aid in the assessment.
System Size: The overall size of the PV system is another important factor. The larger the system, the more complex it is, and the more frequent inspections it may require to ensure that all components are functioning correctly.
Environmental Exposure: PV systems can be affected by consistent exposure to harsh environmental conditions, which can make the inspection process more difficult. Some environmental factors that affect solar farm components and the PV inspection process are beyond human control, but steps can be taken to mitigate the risks. Some examples of environmental factors that can affect solar PV systems include high humidity, extremely high temperatures, wildfires, high winds, hail, salt air, heavy snowfall, and flooding.
Establishing a Drone-based Maintenance Strategy
In conclusion, the frequency of solar panel maintenance and inspections for PV systems is greatly dependent on a variety of factors. Whether your company decides on monthly, quarterly, or yearly drone inspections, there are many best practices and time frames available for each individual solar component.
Ultimately, the inspection frequency will come down to analysis and evaluation for each individual solar installation and collaboration between the asset stakeholders, Engineering, procurement and construction (EPC) Contracts, and an experienced drone company. This will help ensure that the solar PV systems are operating safely and efficiently, and minimize the risks of problems arising.
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