Saving energy is silly; the bottom line is money (was Forklifts tip

> I understand the vectors, in fact, I once proposed hanging a bunch of
> gravitationally coupled solar sails ahead of the earth to move the
> earth back from the sun (over geological time).
>
> The problem with a power satellite is it is in orbit around the
> *earth.* And the force on the satellite is radially out from the sun
> in all places on its orbit around the earth.
If the power sat looks like this at http://www.nss.org/settlement/ssp/
I would agree.

Two large primary mirror arrays pointing toward Sun and trying to keep
the symmetry
while concentrating the energy onto secondary mirrors, which concentrate
the energy
onto the real solar cell array with transmission antenna which points
towards the rectenna.
Looks like tilting and changing pointing would be very difficult if
possible at all.

Why all this mirror-stuff? You only need power generating solar cell
arrays and
the transmission antenna.

I would try to get rid of those mirrors, using a solar cell array and a
transmission antenna
only. Both would be independent spacecraft but connected through power
lines.
While the larger collector-unit with it's solar cell arrays points
toward Sun,
the transmission antenna unit points toward Earth. They both move and
point independently.

The torus-like Solar Power Station would look about like this :
http://solar-thruster-sailor.info/figs/fig11.html

> If you tilt the power
> sat, the non radial force against orbital motion on the near side of
> the earth toward the sun is opposed when it is on the far side of the
> earth from the sun. And changing the tilt of something that big over
> a short time is going to take an awful lot of reaction mass or some
> heavy other method.
>
I think you would change the tilt of the craft gradually during 24 hours,
not twice a day in a few minutes.

In contrast to a solar sail spacecraft, which tries to get out of the
Earth orbit
and is orientated to the Sun for one half of the orbit, while orientated
edgewise
to the Sun on the other half of the orbit, the Solar Power Station could
be orientated
always toward Sun. On the first half of the (Earth) orbit it would be
accelerated on the
second half it would be slowed down using it's pointing capability to
fine tune the process.
> The force egg shapes the power sat orbit, which is not good for it
> staying in the same place over its rectenna.
>
The Power Station would not be exactly above the same place but it could
make good about
that through pointing with the antenna onto the same place.
It could also point onto other rectenna places too.

Best wishes

Frank