I'm a little foggy this morning, but here goes: If 100km^2 is read as an area (not a square 100 km on a side), that's 1e8 m^2. Assuming an average of 500W/m^2

I'm a little foggy this morning, but here goes: If 100km^2 is read as an area (not a square 100 km on a side), that's 1e8 m^2. Assuming an average of 500W/m^2 daytime insolation over 8 hours and an average conversion efficiency of 20%, that's about 1e9Watts (1 GW) average output over 8 hours, or 8GW-hr/day of energy. Assuming 365 days/year, I get about 2.9e4GW-hr/year, or about 29 TW-hr/year. Wikipedia [1] gives the total energy used by civilization in 2013 as about 157 PW-hr, or 157,000 TW-hr. The same source estimates electricity generation alone was estimated at about 19,500 TW-hr in 2013. So 100km^2 of solar panels looks like it could produce about 0.15% of humanity's 2013 electrical energy production or about 0.0186% of humanity's total 2013 energy generation. If the initial solar array dimensions should have been read as 100km x 100km, then its output would be 2 orders of magnitude larger. This would bring its output to 15% and 1.86% of 2013 electrical and total energy generation, respectively. YMMV - these are only napkin calcs, not reviewed for error or fatal simplification. [1] https://en.wikipedia.org/wiki/World_energy_consumption https://en.wikipedia.org/wiki/World_energy_consumption