Mathematically, it would be possible to calculate just how much energy fell on earth in a single day, and actually it would be pretty easy to do that. What we would not know, however, is how much power has been consumed since the day we had electricity on this earth. At best that would only be a wild guess.
Then we would need to know at what efficiency to do said calculation, 100% or something like 15%, the efficiency of a fairly good solar panel.
Sharp has just announced a 35.8% efficiency rating using nanotechnology, which is with us today. Now it is just a matter of time before these types of panels are commonly available.
Nano Solar in California is making them, plus their factory in Germany as well. Unfortunately the whole production is being shipped to europe. At least for now. There is at least one other nano-tech outfit in the US doing this, but their sales are limited to something like 50kw+ in order to serve more communal type needs.
It is here, we just have to be patient.
In the meantime, make your own panels. You can do it for $1/watt. And that is what coal power costs us.
