How to calculate the power incident on the earth s surface?

Your question: "How to calculate the power incident on the earth s surface?"

(1) Collect suitable insolation data from area of interest for time of year of interest.

(2) Select a suitable metric for expressing units of power.

(3) Perform the arithmetic.

Come back when you have figured out item (1).

You probably will not need any more help by that time.

"Solar irradiance is the power per unit area received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering. It is measured perpendicular to the incoming sunlight. Total solar irradiance (TSI), is a measure of the solar power over all wavelengths per unit area incident on the Earth's upper atmosphere. The solar constant is a conventional measure of mean TSI at a distance of one astronomical Unit (AU). Irradiance is a function of distance from the Sun, the solar cycle, and cross-cycle changes. Irradiance on Earth is also measured perpendicular to the incoming sunlight. Insolation is the power received on Earth per unit area on a horizontal surface. It depends on the height of the Sun above the horizon."

• https://en.wikipedia.org/wiki/Solar_irradiance

It's about 1kw/m²