Height Data and Shade Modelling

Shade modelling is incredibly important for rooftop projects in order to make sure the predicted yields will be achieved. Helios’ shade modelling capability is best-in-class.

Where available, recent height maps are used to simulate shading on the modules. Therefore it is important to model your system correctly in relation to this height map and the aerial images with oblique views. This is covered in Defining an Installation Area (Height Map).

Even when there are no underlying height maps, it is fast and convenient to use obstacles to create an accurate simulation of shade. In this case you can also set the height of the obstacle to be relative to the area itself, or to the ground level.

The Dutch height map is based on a colour scheme, where blue is the lowest level and red the highest. This colouring is dynamic, so it will change based on your view. Grey spots mean there is no data available, so you should avoid these in setting area details or taking measurements. 

We do our best to keep this map as up to date as possible, but if for example trees have been cut down or new buildings will be erected close to your site, the height map might need manual changes. You may add obstacles and masks to adapt the height map. Click on the ‘Height data’ tab in the main menu to do so.

You can see the potential shade per module by making a horizon plot. To do so, right click on any of the modules and click ‘Plot horizon’.

A graph will be displayed, that shows;

  • The trajectory of the sun for the location of the system
  • Shade caused from the underlying height map (if it exists)
  • Shade caused by created obstacles.
  • Shade caused by other areas.
  • Shade caused by other module rows for flat roof systems .

You can see this as a panorama picture taken from the location of the module, with the horizon showing all buildings, trees and other objects in the surrounding area.

Clicking the ‘New obstacle’ button will let you add any new data to the height map. Obstacles might be created either within or outside an installation area. After drawing the contour, you can name the obstacle and define its height. Setting the height and what it relates to is important, since this might cause shade on your modules. An obstacle can either be relative to:

  • Installation area: the obstacle’s height will be set relative to the height of the installation area, so the defined height is the difference between the top of the obstacle and the installation area it’s in. This is automatically the case when the obstacle is fully within the boundaries of the installation area.
    • Useful for air conditioning units on the roof or chimneys.
  • Height map: the obstacle’s height relates to a point on the height map, so the height you define for the obstacle will be added to the height of the height map at the given point. Default the center of the obstacle is used.
    • Useful for trees or other buildings.

A mask will ignore all height map data for the given area, so this will no longer affect the yield of your system. Use this if you see objects on the height map that should not be there, like trees that are cut down, installations on a roof that are to be removed or incidental errors in the data.

Drawing and resizing a mask works similar to editing an installation area. Click on the button ‘New mask’, and automatically the height map will be shown so you can see exactly what to select.

You can view the shade loss per module on the system yield page and in the System Report.

It may be useful to open the yield page alongside the module layout window. Every time you save the layout view the yields will be recalculated.

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