OK lets see if I can explain it more clearly.
The sun only sends us 1000W/M^2, the M^2 measured perpendicular to the suns rays.
Now if one can imagine a bunch of straws with a 1M^2 cross section gathered up in a bunch and pointed at the sun, each of those straws delivers us 1 KW of energy.
In any one of these tubes that we gather all the radiation and do not allow to hit the earth, 1 KW can be gathered.
No matter how we gather the energy in any one of these straws, we cannot go over 1000 watts, because after that the straw is empty.
Now after we gather the light from the straws, there is a shadow 'downwind' of that straw.
When the shadow is cast on the earth, it will have AT LEAST one square meter of area that will be in shadow. At high noon on a certain day in the tropics, that shadow will be 1 square meter. At any time other than high noon local time on specific days in the tropics, the shadow will measure more than 1 M^2, as the light hits the spherical earth at an angle different from perpendicular.
The only way to gather more than 1 KW is to harvest more shafts of light... more straws.
In order to gather 3 KW (as claimed) we must gather the light of at least 3 straws. As a matter of practice, the world's best PV cells would need to gather the light of 7.5 straws, because 40% is presently the world record for gathering efficiency.
So 7.5 M^2 of solar collector will cast a shadow on the earth of more than 7.5 M^2 except in very specific geographical and temporal locations.
But lets give him the benifit of the doubt and say he has 100% effeciency on the gathering of light energy.
I can build a 3 M^2 collector and mount it to a superstructure that mounts to a pole sunk into the ground with a footprint on the earth only a foot square, so now is my effective collection 3 KW per sq foot?
No, it is still 1 KW / M^2
And 1 KW / M2 is all that I could dream for. I can never get better than that, unless I go to orbit.