In this paper, we discuss two new paradigms for enabling cost-effective III-V solar cell photovoltaics using (i) our novel layer transfer technology, called controlled spalling and (ii) new solar cell device structures. First, we present the application of the controlled spalling for making high-efficiency thin-film multijunction solar cells. Finally, a novel GaAs heterojunction solar cell structure is described, consisting of thin hydrogenated amorphous silicon stack deposited directly on the GaAs surface at 200 degrees C, aiming to eliminate the III-V epitaxy. This feature in conjunction with a kerf-less removal of GaAs using the controlled spalling technique offers a viable pathway for realizing low cost high-efficiency III-V photovoltaic technology.