Solar Panel Inspection in Preston Identifies 50% of panels are not working efficiently costing hundreds of pounds!

Bleasdale Parish Hall suspected a drop in performance from their solar panels so asked us to investigate.


The Problem

Bleasdale Parish Hall is in the Wyre district of Lancashire, in a beautiful location in the Forest of Bowland. The hall is ran as a charity, being used as a venue for a wide range of social, educational and business functions and events.

To offset energy bills the Parish hall has its own wind turbine, biomass boiler and photo voltaic (PV) panels, as known as solar panels on the roof.

Bleasdale Parish Hills in Forest of Bowland for infrared drone inspection
Bleasdale Parish Hills in Forest of Bowland

The solar panels were installed when the government Feed In Tarif (FIT) was active, designed by government to promote the uptake of renewable and low-carbon electricity generation.

This means that any unused electricity is fed back into the grid and the Parish Hall receive a payment every month for energy generated by their solar panels!

The owners of the Parish Hall noticed a sudden drop in payments by nearly 50%, losing over £1000!

Because the panels are mounted on the roof, they are not easy to access without costly scaffolding or mobile platform.

DroneWorks were asked to inspect the solar panels by drone to determine the where the issue may be to help identify the cause of loss of PV panel performance.

How Can Drones Be Used to Inspect Solar Panels?

Drones have become a vital tool for solar panel inspections, collecting data more than 50x faster than manual methods and improving safety by avoiding working at height.

A commercial Unmanned Areas Vehicle (UAV) or 'drone' equipped with a thermal infrared sensor can detect issues on solar panels that are not visible to the naked eye.

DroneWorks are British Institute of Non Destructive Testing (BINDT) CAT 1 qualified thermographers, experienced to collect infrared data to required standards.

Infrared cameras are not just 'point and shoot' like a traditional camera. They are affected by the atmosphere, weather and event he surface of the building. Specific conditions and knowledge is required to use them effectively.

What Is Thermal Imaging?

Thermal imaging, also known as ‘Infrared Thermography’, uses heat-sensitive cameras to detect differences in temperature. These cameras can detect temperature differences of less than 1ºC.

DroneWorks Infrared Inspection Drone for thermal inspection
DroneWorks Infrared Inspection Drone

With the infrared sensor being mounted on our drone, we can quickly access the solar panels in order to inspect them from the air using both visual imagery and infrared imagery, without working at height.

The drone allows easy access to the roof mounted panels.

This method is very quick, safe and cost effective versus traditional inspection methods with is costly, time consuming and risky to use scaffolding to access the roof.

How Did We Help?

The client contacted us with the problem. We responded quickly and scheduled a date for the site visit, however, there are some off site activities that need to take place to ensure the drone operation can be conducted safely in Bleasdale.


There are regulations and safety issues to be addressed when planning a drone flight.

Firstly we determine the equipment required to conduct the inspection. A different drone or camera may be required depending on the building, the requirements and the area.

Bleasdale is a rural area, with plenty of space and no restrictions enabling us to use our commercial thermal drone which carries a high resolution thermal infrared sensor, perfectly suited for this type of drone inspection.


To enable accurate infrared inspections, certain weather and environmental conditions need to be met in order to meet the International Electrotechnical Commission (IEC) standards for PV panel inspections and also so that the inspection is conducted in accordance with BS EN ISO 62446.

Mainly we need low wind and bright sunshine on the solar panels during the inspection meaning this type of inspection is only performed in the summer months.

On Site

On arrival at Bleasdale Parish Hall, we first conducted an on site assessment to ensure there are no obstructions or other issues that could make the drone flight unsafe.

The solar panel array on the Parish hall consists of 8 panels (also known as modules) divided into two rows (strings).

Roof mount modules on parish hall

On this occasion, we had access to the building and so the main components of the solar panel installation we also check such as the meter and inverter. Readings were taken from the invert which showed with one string of modules producing significantly less watts than the other.

Inverter display showing string 1 producing less watts than string 2
Inverter display showing string 1 producing less watts than string 2

The take off area is marked by cones if required and the drone with FLIR thermal sensor is setup to acclimatise. We will also inform any nearby property owners to make them aware of the drone operation. This helps prevent any unforeseen confrontations. We have previously been accused of 'spying' on peoples property!

Whilst the drone is 'warming up' we will setup instruments to collect environmental information such as temperature, irradiance level and humidity. This information is is regularly recorded and logged as it is used later on during the analysis of the data.

These measurements are set into the infrared camera settings to ensure data collected and shown on screen is as accurate as possible. This is where knowledge of thermography comes into play in making best use of the equipment and later on, interpreting the data is provides.

We met the site owner and after a short brief, launched the drone and positioned it above the modules mounted on the roof of the building.

Infrared images are then collected in a logical manner to ensure all panels have been captured both with a visual and thermal infrared camera to record radiometric data.

Both high level and closer detail images are collected.

In this case, the overview infrared image immediately showed the extend of the problem. The top string of modules is displaying a chessboard type pattern indicating a major issue which will account for the losses reported.

In this case the drone was airborne for around 15 minutes, approximately half a battery.

Initial findings are discussed with the client on site but no detailed conclusions will be made until the data is properly analysed back at the office.

Thermal Analysis and Reporting

Depending on schedule, data will be analysed at the office the same day or next day. We like to provide a quick turn around as fast, accurate data collection is one of the benefits to choosing drones over conventional methods.

Infrared images and video and loaded into specialist software. Images are 'tuned' to ensure we have good thermal resolution in the areas of interest.

Each infrared image will have a corresponding visual image. Each infrared image is analysed in turn, looking for thermal anomalies such as hot spots, dirt, damage, string errors, diode issues and individual cell faults.

Visual images are useful to rule in or out any physical damage or dirt. Eg. bird droppings may show up as a hot spot in the infrared images, but the visual images will show the panel is dirty and simply needs cleaning.

Not only can a fault be identified, but its exact location can be pin pointed, saving time for repair / resolution.

Findings / Outcome

The client suspected a drop in performance of around 50% from their roof mounted solar array. Our findings confirmed this, with 1 whole string, accounting for 50% of the arrays modules, not to be performing as expected.

Infrared image showing chessboard like pattern on top row of modules (short circuit)
Infrared image showing chessboard like pattern on top row of modules (short circuit)

The chessboard like pattern displayed by the modules means they are in short circuit. This could be down to a wiring or connection issues between inverter and modules. So this will be the first thing to be checked and investigated.

Worst case scenario is the panels are damaged or suffering from PID (Potential Induced Degradation).

The client was given a report along with our images, findings and comments which can be used by a PV Installation company to investigate further. More in depth tests can also be performed to pin point the issue if required.

Final Words

Having an infrared drone is one thing, but having the knowledge to capture infrared data to standards AND be able to interpret that data is key.

Aerial surveys or drone surveys are becoming increasingly popular. Time on site is reduced, data is delivered quickly and risk reduced both on site and within the project.

Because drone surveys are quicker and cost effective, they can be easily repeated at a greater frequency than traditional methods.

When thinking about using drones,  make sure that you are using a registered, qualified and insured drone operator.

Get in touch today to ask any questions or discuss your project.

Whether you’re a building surveyor, land surveyor, site engineer or quantity surveyor, there is a use case where drone surveys can provide a considerable benefit.

If you are a surveying business and you are interested in starting your own drone program, please reach out, we’re happy to talk through the process and requirements. Its not as simple as ‘chucking the drone up. There is a considerable investment in training, equipment and software.

DroneWorks are excited to be offering these innovative drone survey services to our clients and proving the benefits that they can bring to projects taking advantage of them!

See more about our infrared services here.



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