Work out solar declination instantly with clear inputs, formula shown and shareable results.
Solar declination is the latitude directly beneath the Sun, swinging between plus and minus 23.44 degrees over the year. Cooper's approximation gives it as 23.44 sin(360(284+n)/365). At the March equinox it is near zero, so the noon Sun stands at 90 minus latitude - 45 degrees at 45 degrees north.
Cooper's declination
declination = 23.44 sin(360(284 + n) / 365)
Noon altitude
altitude = 90 - |latitude - declination|
That is Earth's current axial tilt. It varies between about 22.1 and 24.5 degrees over a 41,000 year cycle.
Within about 0.3 degrees, which is ample for solar design. Ephemeris calculations are needed for arcsecond precision.