Solar panel maintenance is an important aspect of ensuring that photovoltaic (PV) systems are operating at their optimal performance over the lifetime of the system. Today, the most cost efficient and effective way to inspect solar panels is using drones equipped with thermography technology. But how often should PV systems be inspected by drones? The most common inspection schedules for drone-based thermography are yearly, semi-annually, or quarterly. However, additional attention should be given to older PV systems, which will require more frequent proactive maintenance inspections. In this article, we will explore the various factors that determine the frequency of solar panel inspections and discuss the best practices for maintaining PV systems through drone thermography.
Table of Contents
PV Solar System String Outages - Infrared Image
Preventive Maintenance: Inspection Schedules for Aerial Thermography
Preventive maintenance schedules for aerial thermography commonly utilize inspections once per year. These inspections look for a variety of issues that could potentially impact the performance of the solar panels.
"If you’re using drones once a year for PV thermal anomaly detection, that’s great. You’re running your site exactly at industry standards today for preventive maintenance. And if the benefits for deploying drones for solar panel inspections more frequently outweighed the costs, any logical site manager would be running inspections more frequently."
When looking at individual components there are a variety of recommended inspection schedules from monthly, quarterly, yearly, and semi-yearly depending on each piece of equipment and the type of solar installation. Aerial drone inspections play a huge role in setting a proper inspection schedule, and a preventative maintenance plan using an aerial inspection solution would look at a wide variety of items such as:
- PV arrays
- Electrical equipment
- Mounting structures
- Fencing
- Shading areas
- Trackers
- Vegetation
- Animal damage
- Erosion
- Corrosion
- Discolored 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.
Reactive Maintenance: Inspection Schedules for Aerial Thermography
Reactive maintenance refers to addressing any issues as they arise instead of on a regular scheduled routine. This type of maintenance is used to address the unexpected problems or failures that can often occur in a solar panel system. Unlike preventive maintenance, which is performed on a regular schedule, reactive maintenance is performed as the needs arise, usually in response to an immediate problem or malfunction. Reactive maintenance is most often used in conjunction with preventive maintenance. This will ensure any potential issues within the solar farm are identified and addressed in a timely manner and to extend the overall life of the system.
It is important to have a plan in place for reactive maintenance to ensure that any issues are addressed quickly. For example, having a contract with a solar EPC company or an experienced drone service provider can help to minimize the impact of any problems and prevent further damage.
Some of the common issues that may require reactive maintenance include items like:
- Overheating
- Malfunctioning inverters
- Debris
- Damaged trackers
- Failed components
What's included in YOUR GUIDE...
Techniques for Exposing Warrantiable Items on Your PV Sites.
A Proven Roadmap for Successfully Implementing Drones in Solar.
Strategies for Identifying DC Losses and Avoiding Downtime.
Drone inspections can easily identify these issues and help to pinpoint the specific locations on the array. This can save time and reduce the cost of maintenance by allowing maintenance crews to focus on the specific area that requires attention.
In addition to identifying and addressing issues, reactive maintenance also plays an important role in tracking the overall performance of the solar farm. By regularly inspecting the system, businesses can monitor the progress of repairs, track performance over time, and identify trends in issues that may indicate a need for more frequent inspections or a different maintenance approach.
All of which will continue to help minimize the impact of any problems, prevent further damage, and mitigate plant downtime.
PV Solar Tilt-tracker Mechanism Failure - Infrared Image
Measuring System Performance During Commissioning
Measuring the system performance during the commissioning of a new solar PV site is an important step to ensure the entire system is operating at its peak performance level.
Solar site commissioning is the process of ensuring that a new solar PV system is installed, set up, and operating in accordance with the manufacturer’s specifications, applicable laws, customer requirements, and International Electrotechnical Commission (IEC) compliance criteria. To make sure the system is operating effectively and that all components are performing as expected, various checks and tests are commonly performed by a drone pilot.
For instance, a newly constructed 17 MW solar farm located in Virginia, USA encompassing 38,532 modules, 4 inverters, and 80 combiners was inspected by The Drone Life in collaboration with the site’s electrical contractor. During this inspection, an infrared drone captured more than 25,000 thermal and RGB photographs. The data was then examined and processed using machine learning and AI software. The analysis concluded that 1,145 modules had anomalies, with an estimated yearly kWh loss of 402657.75. This translated to an estimated annual revenue loss of $24,159.46 unless these issues were promptly corrected.
Issues with PV systems are most common to find during the commissioning phase. The equipment is still new and unchecked under normal loads. Therefore, it is crucial to ensure appropriate documentation is captured at the commissioning and testing stage for several reasons:
- Compliance – Proper documentation is often required by regulatory bodies to ensure that the system is in compliance with local codes, standards and regulations.
- Warranty – Many components of a solar panel system are still under warranty during the commissioning phase, and manufacturers may require documentation of commissioning and testing to honor warranty claims.
- Performance Monitoring – Documentation of commissioning and testing can be used to establish a baseline of the system’s performance and to track performance over time. This can help to identify if the stated output matches the intended production levels according to the manufacturer’s specifications.
- Maintenance & Troubleshooting – Maintenance crews can refer to the documentation to determine how the system was initially configured and what tests were performed, which can help to identify the root cause of any problems more quickly.
- Future Reference – After the inspection is done, the data collected by the drone is analyzed and the results are used to create a comprehensive report that includes any issues that were identified and recommendations for any repairs or adjustments that may be needed. This report serves as a baseline and reference point for future assessments.
Recommended Inspection Frequency After Site Commissioning
To ensure that the system is working properly, it is recommended to utilize inspections every 3–6 months for the first year after the site is commissioned. This allows businesses to track the system’s performance over time, identify any trends in issues, and make any necessary adjustments to the maintenance schedule. By monitoring the system’s performance and adjusting as needed, businesses can ensure that their solar panel system is operating at its optimal performance for the entire lifespan of the system.
Related Article – O&M Teams: Here are the Top 5 Best PV System Inspection Methods
Factors that Determine Inspection Frequency
Determining the appropriate frequency for conducting drone inspections of a solar PV system or solar farm is crucial for maintaining the system. Solar components have many variables, each with their own complexities and ideal review intervals, which affect the inspection frequency. Finding an ideal inspection frequency is unique to each site, but is mainly affected by these five factors:
1. Age of the System
A key factor in determining inspection frequency is the age of the system. A recent study by researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory determined that newer sites actually degrade less than older sites. Therefore, newer systems generally require less frequent inspections than older systems, and they are less likely to develop problems over time. As the system ages, the likelihood of issues arising increases, and so the frequency of inspections should increase accordingly. If a commissioning inspection was performed at the time the site began operations this historical drone data can aid in the assessment.
2. System Size
Another important factor is the overall size of the PV system. The larger the system the more complex it will be and may require more frequent inspections to ensure that all components are functioning properly.
"As with any new industry, the pace of innovation in utility-scale solar is high. Thankfully that also applies to the field of risk management for utility-scale solar projects. As the industry evolves, data around best practices have started to emerge."
Risk is another key factor to consider when determining the inspection frequency for larger solar farms. As the size of a solar farm increases, so does the potential for risk to the surrounding community and environment if the farm is not properly maintained. Advances in risk management for utility-scale PV systems have helped the solar industry tremendously, but inspections are still needed to evaluate risk.
High-voltage PV systems are another dimension of system size when determining the frequency of inspections. The complexity of these systems can increase the chances of problems arising if they are not properly maintained. Drone inspections can help mitigate these risks by ensuring that the systems are operating safely and efficiently while at the same time removing many of the safety risks technicians encounter when interacting with high-voltage systems.
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3. Environmental Exposure
Environmental exposure is another important factor that determines the inspection frequency of solar PV systems. Consistent exposure to harsh environmental conditions can affect solar farm components, and the PV inspection process as well. Many of these issues are outside human control, which makes them more challenging to predict and address, but steps can be taken to mitigate the risks when available.
Examples of these include:
- Humidity – which can cause corrosion of equipment and affect their performance.
- Extreme high temperatures can cause thermal stress on the equipment and degrade its performance.
- Wildfires – tracking maintenance issues due to wildfires is still relatively new and while data is now being collected and analyzed, initial findings indicate that there is significant loss of production due to shutting down the systems.
- High winds – the possibility of hurricanes or tornadoes can cause damage to the system, breakage of solar panels or structural damage to the mounting systems.
- Hail – can cause PV module breakage.
- Salt air – marine environment can cause corrosion and soiling which can affect the performance of the system.
- Heavy snowfall – which has the highest impact on solar production, can cause damage to the array and lost energy production.
- Flooding – high rainfall and water intrusion into enclosures can cause damage to the systems and affect their performance.
Drone inspections are challenged with environmental conditions as well, but inspection schedules can be adjusted to ensure that the system is operating safely and efficiently, and to minimize the risks of problems arising.
4. Mounting Technologies
Mounting systems play a crucial role in determining the inspection frequency of solar PV systems. Commercial and utility-grade PV systems are installed in a variety of ways but generally fall into four categories: ground-mounted, rooftop, canopy, and floating. Each of these configurations, no matter their size, can easily be inspected with drone thermography, especially the systems which are more difficult to access by manual inspection procedures.
The rise of tilt-tracker and floating solar systems has increased production yield with innovative land utilization techniques. However, these installations often involve more moving or complex parts that can fail sooner than more traditional mounting technologies. This results in a need for more frequent inspections to ensure that the systems are operating safely and efficiently. Drone inspections can effectively reduce these weaknesses, especially with floating solar systems which require remote access.
The offshore floating systems are more difficult to maintain than their onshore counterparts based on accessibility alone. Since the latter can be accessed by motor vehicles whereas the former requires a boat, making daily maintenance a huge challenge.
Rooftop PV installations also require special attention when it comes to fire prevention. As the risk of financial or human loss is much higher, keeping on top of fire warning signs is especially important when operating these systems. Routine inspections can help identify potential fire hazards and introduce steps of remediation to prevent them in the first place.
5. System Performance
Finally, system performance is another important factor that determines the inspection frequency of solar PV systems. One of the key indicators of system performance is the existing production output of the system. If production is significantly less than normal, a system-wide inspection is often performed. This is because a decrease in production can be a sign of a problem with the system, such as soiling on the panels, shading of the panels, or damage to the electrical systems.
Additionally, monitoring the performance of the system on a regular basis can also help detect and prevent any potential issues. For example, monitoring the performance of the inverters, the DC-AC conversion, and the AC-grid connection can provide early warning signs of future problems. By tracking the overall performance of the system over time, patterns and trends can be identified before they amount to larger issues.
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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 including the age of the system, system size, environmental exposure, mounting technologies, and system performance.
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 an analysis and evaluation for each individual solar installation and collaboration between the asset stakeholders, the EPC, or 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.
Are you looking to evaluate your own solar facility to determine the best inspection frequency? The Drone Life works with a broad range of companies that manage large and small solar portfolios. We have direct experience creating tailored aerial solutions specific to your needs. You can schedule a free consultation with a drone expert today.
What's included in YOUR GUIDE...
Techniques for Exposing Warrantiable Items on Your PV Sites.
A Proven Roadmap for Successfully Implementing Drones in Solar.
Strategies for Identifying DC Losses and Avoiding Downtime.
