The calculator results show the estimated annual solar energy generation and month by month figures for an unshaded and a shaded solar system, as well as the reduction in solar energy generation due to shading.  

The results are shown as a table and a graph.  Example:

Image example of Estimated generation results shown as a graph

Shading can be reduced by increasing the setback of the adjacent building, locating solar panels higher on the roofline (closer to the roof peak) or locating panels on a roof face that is less subject to shade.

You can test the results of any changes by re-running the calculator.  The aim is to achieve design changes that result in bringing the red line as close as possible to the blue line, especially over summer when most sunlight is available.  

Current planning provisions generally maintain 70% of annual solar system generation (compared to no overshadowing) due to setback requirements. If the calculator estimates a lower figure, the need for a more detailed assessment is indicated and a discussion with the developer, council or building surveyor might be appropriate.

Page last updated: 22/11/19