Little Inc., which would use very large arrays of photo voltaic cells to make the conversion directly into energy. The other major design is by Gordon Woodcock of Boeing Aircraft Corporation, proposed having conventional turbogenerators operating on a Brayton cycle with helium as the working fluid.
The key product in the solar power stations is solar cells, which does the actual converting of energy into electricity. A useful material is found in lunar soil is silicon which is used to make solar cells. So we can produce a large amount of these cells and then we can avoid any problems of shipping the material from earth. Cells convert sunlight directly into electricity and this could be used to supply the electricity for the construction and operation of the space colony. It would be simple to put together large scale solar collectors and mirrors around the colony. A solar cell is made from two thin layers of material, usually silicon, which has been prepared in a special way. The net effect of this arrangement is that the sunlight falling on the cell shakes the electrons loose in the material, then these electrons move off into an outside circuit, which is detected as an electrical current. Things are arranged so that most of the work involved in generating the electricity is done by forces associated with the atoms themselves, with no energy input other than sunlight. So getting energy from the sun would seem pretty easy. All we"d have to do is just make enough solar cells to collect the amount of energy we need, put them in the light, and sit back and watch the electrons flow.
In space sunlight is a pretty diffuse form of energy and that could cause some problems. Even if we could convert sunlight to electricity at one-hundred percent efficiency, it would take a sheet about three feet on a side to power an ordinary toaster. This is why designers of solar power satellites are driven to talk about very large structures.
