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Data Input Requirements for Solar Thermography (fka Essential)
Data Input Requirements for Solar Thermography (fka Essential)

This article will cover the data input requirements for the Solar Thermography data product

Updated this week

Introduction

Making sure that the results we deliver to our customers are the quality they expect start with how the data is acquired. Making sure that we have all of the data that we need in, delivered in the way we expect will make sure processing runs as smoothly as possible.

However, capturing these thousands of images might be challenging. Therefore, we created this article, considering the best practices to save you time and frustration during the data acquisition.

This article will cover the following requirements for the Solar Thermography data product:

  • Flight plans (RGB & Thermal)

  • Tips depending on your site type

  • Site As-builts


Flight plan

For the Solar Thermography data product, we require visual (RGB) and thermal photos. A drone pilot will use an unmanned aerial system (a drone with a camera) to capture the data on-site.

Visual (RGB) Data Requirements

  • Ground Sample Distance (GSD): 1.0 - 1.5 cm per pixel at ground level.

  • Front Overlap: 70%.

  • Side Overlap: 30%.

  • Flight Line Direction: Along the long edge of the solar rows.

  • Flight Path: At least 2 flight lines should be outside the boundaries of the operation in all directions.

  • Gimbal Orientation: standard Nadir (-90 deg), with acceptable deviation up to 20 deg to avoid sun glare.

  • Image Format: JPEG.
    Each image should contain the following metadata: GPS location, relative altitude, gimbal pitch, gimbal yaw, gimbal roll, and local timestamp.

  • Image Quality: in focus, free from motion blur and minimal glare.

Thermal Data Requirements

  • GSD: 5.5 cm per pixel at panel level.

  • Front Overlap: 70%.

  • Side Overlap: 30%.

  • Image Resolution: 640x512 pixels.

  • Flight Line Direction: Along the long edge of the solar rows.

  • Gimbal Orientation: standard Nadir (-90 deg), with acceptable deviation up to 20 deg to avoid sun glare.

  • Image format: R-JPEG or Radiometric TIF.
    Each image should contain the following metadata: GPS location, relative altitude, gimbal pitch, gimbal yaw, gimbal roll, and local timestamp.

  • Image Quality: in focus, free from motion blur and minimal glare.

  • Environmental Conditions: Aim for a clear blue sky. If a cloud passes, wait 10-15 minutes for the panels to heat up again. Successive flights should not exceed 15 minutes unless it is a new flight block. Wind speed below five m/s, humidity ideally less than 60%.

  • Irradiance: β‰₯ 600 Watt/sqm

Special Considerations for Single-Axis Trackers

Trackers should be as horizontal as possible, up to a maximum 50-degree tilt. Avoid flying in the early morning or late afternoon when the sun is low at the horizon to minimize inter-row glare.

Special Considerations for Double-Axis Trackers

Trackers should be as horizontal as possible, up to a maximum 50-degree tilt. The entire tracker should be visible on at least one photo. Otherwise, increase the altitude.

Example of image alignment

Example of image alignment

Rooftops

Flying a rooftop? Check out this support article on how to adapt your flight plan to fly rooftops correctly.

Blocks

  • To ensure weather conditions are kept homogeneous across the entire solar inspection, sites larger than 30ha should always be divided into separate blocks.

  • To ensure a margin of error lower than 10% for the Ground Sample Distance [in cm/pixel], sites with elevation differences greater than 10 meters should always be divided into blocks. Also, you need to take off from the highest point within the block.

  • Blocks should be flown as separate flights from each other but as much as possible one block should contain one flight. If you need to switch batteries, there should be minimum downtime for the flights in the same block.

The Sitemark platform does not let you cut sites into blocks. Reach out to our support team to let them know, and they will cut the site into blocks on your behalf.


Site As-Builts

We identify the thermal anomalies in the Solar Thermography using the raw data. We need an up-to-date, accurately geo-referenced as-built plan from your solar site to mark the anomalies on the map.

This should be uploaded on the Sitemark platform as a site overlay. The site as-built, is crucial to ensure all of the geospatial data is mapped correctly.

It is very important that this document is verified and uploaded to the platform before the operation in case there are any issues with the document.

You can use this support article if you have not uploaded your site documents before to help you with this.

If it's the first solar inspection on a specific site, we strongly recommend ordering a Solar Site As-built to have a high-quality geo-referenced map of your solar site. This will also enhance your experience with the features on the Sitemark platform.


PDF As-built Requirements

The PDF As-built plan needs to meet the following requirements:

  • It should be recent to match the site as closely as possible.

  • It needs to show each solar panel.

  • It should be accurately scaled so it can be geo-referenced on the map.

  • It must show clear physical reference points, such as roads, buildings, rivers, tables, panels, etc.

  • It should be uploaded in PDF or DXF as site design file in the platform.

  • It should be uploaded before the confirmation of the operation.
    It is important that, if there is only a PDF, some site reference points on the as-built must be visible on the satellite image in the platform so it can be accurately geo-referenced on the map.

  • It should cover all areas that are going to be analysed.

  • It should not be hand-drawn or low-quality scanned site plans.

Some examples to show a good and a bad as-built plan.

βœ… Good - every module is clearly visible.

An example of a good quality as-built plan

❌ Not good - modules are not visible.

Example of a bad as-built plan

❌ Not Good - the resolution is too low, meaning we can not use any reference point from the as-built to locate on the map.

Another example of a bad quality as-built plan

DXF As-built Requirements

The DXF As-built plan needs to meet the following requirements:

  • The CAD drawing should be georeferenced as the EPSG needs to be provided on upload to the platform.

  • The CAD file cannot contain any blocks. If the panels/banks are in the drawing as a block, they must be exploded into polylines. The platform does not support blocks.

  • Xrefs are not supported. Any Xrefs should be inserted into the main CAD file.

  • There can be no hatches in the CAD file. The platform cannot display hatches.

  • The drawing should be purged before saving to remove un-required layers.

  • The CAD file needs to be provided as a DXF 2010 version.

  • The DXF should be <500MB.

  • At the moment, the text is not supported. Therefore any text within the DXF will not be displayed on the platform.


I do not have my own As-built document. What should I do?

If you do not have an as-built from your site available, use the Solar Site As-built data product from Sitemark. We can help you to generate the as-built from your solar site. Please contact your account manager or our support team for more information about this data product.

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