Photovoltaic inspections with drones

In the following article, we see the practicability of a drone in the area of photovoltaics and the common type of defects encountered.

About:

Solar panels inspection is usually underrated, most claims say that if there is a problem they would see it as energy production drop. Unfortunately, this isn’t an effective way of identifying defects, as weather-related factors like temperature, humidity, cloud cover, sunlight, radiation angle and others change every day and cannot be compared. Depending on the park size and monitoring system, major defects such as inverter shutdowns can be detected but even then it can be hard to pinpoint the exact location of the affected panels and inverter.

Challenges

The biggest problem with this type of detecting method represents the smaller, cell and diode defects. They break over time, 1 by 1 and are responsible for a very little amount of power loss, practically indistinguishable from day to day power production. But in time, defects like this add up to significant figures of power loss and financial impact. For this reason, preventive maintenance is a very important aspect of keeping a solar park at its maximum efficiency.

Technology

Another important aspect of thermal inspections of a solar site is the fact that it can accurately spot defects that are not detectable with the human eye. Traditional methods, by comparison, are very time consuming and simply not worth the time. Combining thermal vision with the mobility and versatility of drone technology you get a very fast, reliable and precise way to inspect all the aspects of a solar site.

For this solar inspection, we’ve used industrial-grade drones and specialized cameras with thermal vision that produce high-resolution thermal images.

External factors

For this kind of inspection, there are some important factors to keep in mind, otherwise, the data collected has a high risk of being compromised. We thoroughly check and make sure the weather is appropriate, no cloud cover is present and solar panels receive the proper amount of solar radiation.

Table of contents

Types of defects encountered:

There is a long list of defects that can be detected with drones and thermal cameras, even PID (a subject that will cover in a future blog post) but we will focus one the most common ones in this article.

Starting with the most common one, we have solar cell anomalies.

The solar cell anomalies are very common and, in most cases, just a few of them are present on the same panel. Usually, quality control issues are the main cause of this type of defects.

Here is an example of a more severe case, many individual cells from the same panel are affected. For comparison, we have an RGB image, where everything seems ok but actually isn’t, and the majority of the panel is affected. This kind of defect is hard to spot using traditional methods, that require an actual technician to manually check every panel and cell to pinpoint the faulty ones.

Another common type of failure is diodes. The energy production impact is higher, due to the number of individual cells affected; but in most cases, there are fewer diode defects then cell defects so overall the total energy production affected is lower than individual cell defects.

Usually the panel is divided into 3 sets of cells connected in series, in our example we have a panel with 72 cells divided into 3 sets of 24 cells (2 rows) connected in series, that means if one fails, one third (1/3) of the panel is affected – thus a higher impact on energy production.

We can see in the image above an example of multiple diode failure, affecting one-third of the panel. In the RGB image, we can’t spot this defect, the same as in cell level defects example – everything appears normal.

Defects with the highest impact on power are inverter anomalies. Although they are not that common, they are important to mention due to the role they plan in a photovoltaic power station.

Image credit – Raptor Maps

Inverter problems are easy to spot from a distance, as they affect entire strings and modules.

Benefits:

From a photovoltaic solar station owner perspective, there are a few key advantages that make classic inspection obsolete.

  • It’s easy – Having a DSP doing the inspection saves you from all the hassle. All you need to do is to give the approval, location, and site as build plans (if you have them) and we will take care of the rest. Say no more!

  • Reliable – Precise, state of the art equipment for the best quality data. Thorough reports, pinpointed anomalies and experienced pilots assure the best inspection experience.

  • Time – No time investment needed from your side, we do all the work – fast. Drone inspection is about 10 times more efficient and needs 90% less inspection time than traditional methods.

  • Money – Know exactly what financial impact anomalies have now and estimates over time, so you can make better decisions regarding your assets. Periodic inspections are cheaper and efficient compared to a technical team on payroll – With an average of 2,250€ /MW annual ROI

  • Scalable – Flexible and customized service to match your exact needs, adaptable for your plant MW size, your solar panels angle and much more.

Assessment:

Based on all the data collected with the drone and thermal camera, the inspection ends with a report. Which, among others, contains maps with the exact location of every anomaly and financial estimations.

The anomaly map comes very handy at visualizing and finding the defects, which saves a lot of time on the field. If the site already has an as-built map or numbering structure, we will use that to create and locate panels on the map.

The findings example table above contains data about financial estimations, defects, affected power and power DC percentage as well as overall estimated annual impact. All of this data can be adjusted for your local situation, like the price per kW-hr.

If you would like to download a real-world sample report, please complete the data below:

Conclusion:

If you know your solar farm like the back of your had and think you can identify any anomaly and defect when it happens – great! but we can assure you we can find defects that you didn’t know about. Don’t believe it? Contact us and we’ll prove it.

Questions?

Don’t hesitate to contact us!

+40 724 339 757
office@skylinedrones.ro