Hello 1. The problem statement, all variables and given/known data How much time does it take to the sun to furnish an energy of 10 000 KWh on a surface of 31 700 m². 2. Relevant equations Stefan-Boltzman law ? the power radiated from a black body = σ*T4 3. The attempt at a solution I don't know how I can find the time, I don't know any equation that depend on t to find it, if someone can explain me, that would be great ! Thank you !