Hi Peter, I'm not sure to have clearly understood your question. However I think the following elements can be useful for your problem.
The program Orologi Solari can plot the diagram of the lighting conditions of a panel depending on its position (latitude and longitude) and its orientation (declination and inclination). This can be obtained for south latitude places too. The following image is f.i. the plot that can be obtained for latitude 45⁰ south, longitude 15⁰ east, wall declination 180⁰ (i.e. due north) and wall inclination 90⁰ (i.e. vertical). Date lines are related to zodiac dates rather than year months as this graph is related to sundials. Black lines are related to lighting conditions, light yellow lines to shadow conditions. [image: image.png] I think that in your graph care should be taken in order to avoid any line segment that is greater than 90 degrees, because that is the symptom of a 0-360 degrees azimut jump. That is what has been done for the attached graph. A second solution could be the use of a polar graph as in the following example. I think this can be a little more difficult to understand at a first sight but it has the convenience of avoiding any abrupt line jump. [image: image.png] I hope I've grasped the gist of the matter and that my brief considerations have been helpful. Best regards. Gian Casalegno Il giorno mar 22 lug 2025 alle ore 14:02 Peter Mayer < [email protected]> ha scritto: > Hi, > > I've just had some additional solar panels installed, this time on a > south facing (Southern Hemisphere) roof. I was initially concerned that > the installers hadn't used risers to give them a bit of a more northerly > inclination. To get a clearer picture, I dug out a clever bit of Excel > that Greg Pelletier put together over 20 years ago. Thank you Greg! > > You may see that for the Northern Hemisphere, the diagram (for NH > Spring) is perfect. But when I put in a southern latitude, the result is > unsatisfactory. The problem of course, is that, facing North, when the > azimuth gets to noon, there is a sudden jump from zero to just under > 360. What I am stumbling on is how to define the x-axis so that the > split doesn't occur. Suggestions gratefully received! > > best wishes, > > Peter > > -- > ----------- > Peter Mayer > Department of Politics & International Relations (POLIR) > School of Social Sciences > http://www.arts.adelaide.edu.au/polis/ > The University of Adelaide, AUSTRALIA 5005 > Ph : +61 8 8313 5609 > Fax : +61 8 8313 3443 > e-mail: [email protected] > CRICOS Provider Number 00123M > ----------------------------------------------------------- > > This email message is intended only for the addressee(s) > and contains information that may be confidential > and/or copyright. If you are not the intended recipient > please notify the sender by reply email > and immediately delete this email. > Use, disclosure or reproduction of this email by anyone > other than the intended recipient(s) is strictly prohibited. > No representation is made that this email or any attachment > are free of viruses. Virus scanning is recommended and is the > responsibility of the recipient. > -- > https://www.adelaide.edu.au/study/ > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > >
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