Realization solar power availability in the Main Belt

>
> I got stuck in a traffic jam last night and stopped in a bookstore rather
> than sit in traffic. I purchased the 3rd edition of the High Frontier,
> and was reading in the parking lot that solar energy is 0.18 kW / m^2 on
> the surface of the Earth whereas it is 1.4 kW / m^2 in HEO. The book said
> this was a ratio of "almost 10", apparently proving that O'Neill could do

This number varies a lot depending on local conditions.
Note that it is a time averaged number, for example it includes the 50%
day/night cycle.

In some locations the ratio is 20:1

In polar regions in the long dark winter it is infinite.