Maximizing Solar Plant Power Output and Reducing MTTR

Maximizing Solar Plant Power Output and Reducing Mean Time to Repair (MTTR) with Frequent Thermal Inspections

4 Jul 2024 Written by Naomi Stol Zamir

Global solar power production is rapidly growing, with some experts predicting utility-scale solar could generate up to 25% of the world’s electricity by 2050.

But reaching this lofty goal means utility-scale solar companies must overcome common solar challenges impacting plant efficiency. For example power losses caused by shading and soiling, which can vary from 10% to 70%. Meanwhile, a UK-based thermal inspection of 3.3 million PV modules found that 36.6% of the modules were defective to some degree.

Identifying defects and other issues affecting the power generation of solar panels — and repairing them as soon as possible — is mission-critical for maximizing power output and improving Mean Time To Repair (MTTR).

We’ll be breaking down how autonomous multi-drone data capture and AI analytics can help unlock new levels of inspection efficiency, providing solar plants with deep insights into the current state of their solar panels performance and operations as a whole.

How Do Drone-Based Solar Plant Inspections Work?

Unlike other renewable energy sources, solar plants may lack the major moving pieces found in wind turbines or hydroelectric dams.,But solar panels have their own range of possible issues that must be identified and repaired to maximize the plant power output. 

Thermal imaging is at the heart of solar plant inspections. This technology detects infrared radiation from the solar panels and processes them into an image demonstrating heating and temperature differences. Autonomous drones can fly on a predetermined path, customizable to the specific plant, and capture thermal images of all the PV modules of the solar plant. 

These images are processed and analyzed to identify anomalies throughout the solar plant, as modules with defects will show a distinct difference in temperature. The resulting insights can then be used by operations and maintenance (O&M) managers to prioritize and plan repair work for their teams.

The Problem with Historical Inspection Methods

Inspecting solar panels with thermal imaging tools is standard practice today. However, before drone technology became widely available, these inspections relied on handheld tools. This approach came with several drawbacks, including:

  • Handheld tools are time-consuming: These tools require technicians to inspect each panel individually. For larger plants, these inspections can result in high payroll costs.
  • Manual inspections are partial: Because they are time-consuming, in most cases only a minor part of the plant is inspected, usually 10%-25% of the panels.
  • Manual inspections have safety concerns: Technicians need to spend long hours very close to active electrical components and heated panel frames. 


Combined, each of the issues contributes to the standard of conducting inspections annually. They’re costly, time-consuming, partial, and potentially hazardous, so more frequent inspections are unappealing. 

Fortunately, drone inspections eliminate each of these issues with fast, accurate, and safe aerial inspections. They can conduct faster, more accurate inspections to identify anomalies and reduce the time necessary to repair them. 

What Defects Can Drone-Based Inspections Identify?

Equipped with thermal imaging cameras and mission planning software, drones can be programmed to fly autonomously to capture data about every component of the solar plant. From there, that data is processed by a special analytics platform to identify anomalies and provide detailed insights into how to address them. 

Let’s break down the major categories and types of defects this software can identify:

  • Sub-module: Sometimes defects and flaws in small portions of a panel reduce power generation even if the panel is still operational. Sub-modules anomalies include:
    • Individual cell
    • Hot spot
    • Bypass diode
  • Module: Complete PV module issues can sharply reduce power generation; identifying and repairing defective modules is crucial. Thermal inspections can detect the following types of anomalous issues:
    • Damaged module
    • Missing module
    • Offline module
  • Multi-module: Multi-module defects involve several adjacent  panels, and usually point to issues related to the chain of the electrical system elements:
    • Inverter
    • Combiner box
    • String
  • Variable: There are other possible issues that both range in severity and possible causes. Each of these concerns can prevent modules from receiving a full, complete view of the sun:
    • Physical obstruction
    • Vegetation
    • Shading


For every detected issue there is an estimated annual power loss, allowing O&M service managers to prioritize and plan the necessary repairs to return the plant to maximum power generation.

Infrequent Inspections Are Directly Impacting Your Revenue  

New autonomous drone technology has made inspections easier than ever before. Conducting annual inspections isn’t enough today. With low-cost inspections available, performing annual inspections means undetected issues will translate to lost revenue.

The International Electrotechnical Commission has developed IEC 62446-3:2017, a standard for thermal inspections of solar farms and how to perform them, informing Operations & Maintenance (O&M) programs. While annual inspections are a fine baseline, they should be considered the bare minimum and not the optimal inspection schedule.

Issues, defects, and damage that occur between inspections decrease power generation, in some cases severely. If something happens right after your annual inspection, it will cut into your power output for an entire year until it’s caught on the next inspection.

Additionally, the Mean Time to Repair (MTTR) for these types of issues will be extensive. Even a moderate issue that has to wait months or a year to be repaired will have significant repercussions on this metric and lost revenue.

Making the Case for More Frequent Inspections

Reducing the detection time of anomalies allows issues to be repaired before they worsen so the solar farm can prevent their power loss and increase the expected power output. For example, an unidentified PV module “hot-spot” can spread and become bigger, or vegetation can project a bigger shadow on modules if it continues growing without trimming.

If we consider annual as the standard, more frequent inspections reduce the average detection time significantly, for example:

  • Annually: 6 months
  • Twice a year: 3 months (50% less than annually)
  • Three times a year: 2 months (67% less than annually)
  • Quarterly: 1.5 months (75% less than annually)

The more often you inspect, the further you can reduce detection time frames and repair time frames — directly enhancing power generation and revenue.

4 Reasons Why Ad Hoc Inspections Are Necessary

There are many reasons to conduct ad hoc inspections. These include:

    • Maximize warranty claims: Performing special inspections can help support a larger warranty claim for many underperforming PV panels. These inspections will provide verifiable proof that the panels are underperforming.
    • Improve terms for mergers and acquisitions or refinancing: Re-financing and M&A deals both require due diligence to close. A potential plant buyer will want to see an inspection detailing potential risks. Demonstrating output and efficiency can improve terms for a potential deal.
    • Conduct extreme weather damage assessments: What agreements are in place for ad hoc inspections, such as following extreme weather? You may need to wait for an opening in your vendor’s schedule, extending downtime and likely incurring additional costs from your partner. That’s a direct reduction in revenue and an increase in expenses due to extreme weather.
  • Support and justify repowering projects: Justifying a repowering project requires having useful data. Ad hoc inspections can detect performance issues, highlighting what equipment should be replaced to improve output. These inspections also help identify which underperforming panels should be replaced without exceeding a farm’s total licensed capacity.

How Often Should You Conduct Inspections?

You’re likely already using drone inspections to assess your equipment. The real question is, how often should you be conducting these inspections? 

Inspections follow the law of diminishing marginal returns. Every additional inspection adds less value than the previous one within a certain time period, as fewer new issues are going to be detected within a shorter time period from the last inspection. 

However, as long as this marginal added value of detected and prevented power loss is higher than the added inspection cost, it’s well worth investing in additional inspections to repair any issues and maximize output in shorter cycles.

Identify Issues Earlier, Return to Full Power Faster

The sooner you know about a problem, the sooner you can fix it and keep the solar plant at optimal power output. 

Additionally, drone-based inspection coupled with AI-based analytics and digital twin software take the benefits even further. They not only help reduce the issue detection time but also assist in prioritizing the repair work and reducing the MTTR due to advanced capabilities.

The right platform allows you to group issues by type, sort them by their estimated power loss, and filter them by their section/array location — all to help you streamline work orders dispatched to the relevant O&M field teams, like PV module experts, electricians, cleaners, gardener, so they can expedite their response and resolution times.

Team Up with vHive for Autonomous Drone Inspections with AI Analytics to Maximize Output

Thermal imaging capabilities and drone inspections provide unparalleled inspection speeds and increased accuracy to identify anomalies affecting power generation.

Leveraging an end-to-end inspection solution with autonomous, multi-drone capture, AI-driven analytics, and digital twin software allows you to rapidly inspect the solar plant, identify issues, and start resolving them. 

The direct result of these inspections is returning the solar farm to its optimal performance rather than letting the issue reduce your production and degrade until you’re left with costly repairs. 

vHive is an industry leader in autonomous drone software, digital twin technology, and AI-driven analytics; all focused on helping you run a more profitable, efficient solar plant. Ready to learn more about how our platform can help? Book a demo today to learn more. 

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