Question

the value of solar constant of sun

Answer 1

solar constant = 1.4 kW/m^2

hope this helps

Answer 2

It is the most accurately measured from satellites where atmospheric effect are absent. The value of the constant is approximately 1.366 kilowatts per square metre. The 'constant ' is fairly constant increasing  by only 0.2 percent at the peak of each 11 years solar cycle