The graph was made based on the input from the website as mentioned earlier and calculated for the location at Averbode (Belgium) using Excel. Calculations done for the first day of the month from Jan till June. Using every time the first day results in the orbit of the sun not crossing the 90/270° in March. Of course this will happen at March 21st - Springtime.
Curious to see of the solargraph will show the same pattern.... :)
