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Solar Power Panel Installation Planning using Photogrammetry

The challenge 

The aim of this showcase was to produce an accurate solar power panel layout for installation on a rooftop using photogrammetry software. The targeted roof covers a three-story (single-apartment) townhouse with a high/(elevated) ground floor in Ljubljana. Roof access is difficult.  

The Problem

When planning a rooftop solar power panel installation, an inaccurate plan and/or unfamiliarity of a roof surface and possible infrastructural objects (AC, chimney, vents, windows, etc…) is the biggest obstacle. It is difficult to measure the roof to determine its exact shape and slope. It’s not uncommon for a customer to hand over a roof plan which turns out to be faulty, unreliable or inaccurate. Installation team arrives at the location only to find an additional snow guard, air vent or an AC unit that wasn’t in the original plan or that they did not expect. 

The solution

It’s very easy to plan a solar power panel installation with an accurate 3D model than includes all the roof elements of an object. The 3D model is metric and set in the local/national coordinate system, and as such it represents an ideal starting point for the project planning; one can observe the object’s characteristics, foresee the advantages and the shortcomings of the conceptual design. The software enables the user to draw the elements of interest and even import CAD drawings into the 3Dmodel.

The project 

With a DJI Mavic mini 2 drone we scanned the roof from the average heigh of 25 m. Images ware take automatically, every 3 m. This ensures sufficient overlap (70-80%). During a short 5 minute flight the drone captured 83 images. Manual measuring tools were used at the location to provide the scale reference.

With 3Dsurvey photogrammetry software, a georeferenced, coloured, 3D point cloud was calculated out of the captured images. The processing took 30 minutes. Based on this point cloud a full 3D mesh was calculated. The measurements we took on-site were used to scale the model to realistic dimensions. Original/processing error was less than 2%. Now we have got an accurate 3D model of the house.

Next step was to digitalise the edges of the roof and all the obstructing elements on it. We vectorised the roof ridge, gutter, chimney, windows, air vent, etc. This provided us a canvas to draw the solar panels on each roof plane and arrange them in an optimal position. The panel dimensions are 1134mm x 1722mm. Due to an accurate model, the panels were arranged in less than 30 minutes, positions of limiting elements like windows and chimney were taken into account. Obstacles like the chimney and the snow guard were successfully avoided. 

Vectorized 3D data was exported in DXF format and sent to the Solar Power Plant designer. There they were imported into the SolarEdge software, further calculated for energy needs, and the project finalised.


With the aid of a photogrammetric process, we successfully designed a solar power panel installation map for a rooftop. We obtained accurate building dimensions and ensured the optimal layout of the panels without even stepping on the roof. Thanks to 3D design, the calculation of the solar panels was efficient, smooth and accurate. Further planning of the supporting construction was easy and free of surprises.

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