The deployment of solar photovoltaics has to expand to a scale of tens of peak terawatts in order to become a noticeable source of energy in the future. All the current commercial solar cell technologies suffer from natural resource limitations that prevent them from reaching terawatt scales. These limitations include high energy input for wafer-Si cells and material scarcity for CdTe, CIGS, wafer-Si and amorphous Si cells. We examine these resource limitations under the best scenarios, i.e. the maximum possible power from each of the cell technologies. Without significant technological breakthroughs, these technologies combined would meet only 1-2% of our energy demands in 2100. Without significant increase in raw material production, the deployment of these technologies combined would likely plateau at 100-200 GWp/yr. This analysis identifies several high-impact research directions for amorphous Si cells including substitution of Ag and ITO with earth-abundant Al and ZnO or TiO2-based TCO.