The solar constant is the total power radiated out into space by the Sun. Most of this radiation is in the visible and infrared part of the electromagnetic spectrum.
This value directly relates to the maximum solar energy that reaches a square meter of Earth's atmosphere directly facing the Sun. It measures about 1370 watts per square meter (W/m²) and represents the maximum power you could theoretically collect if you had a solar panel that was 100% efficient and perfectly oriented toward the Sun
The solar constant varies slightly (around ±3%) over the year due to Earth's elliptical orbit, with energy received being slightly higher when Earth is closest to the Sun and slightly lower when it's furthest.
