The typical reference system-of-systems involves a significant number (several thousand multi-gigawatt systems to service all or a significant portion of Earth's energy requirements) of individual satellites in GEO. The typical reference design for the individual satellite is in the 1-10 GW range and usually involves planar or concentrated solar photovoltaics (PV) as the energy collector / conversion. The most typical transmission designs are in the 1–10 GHz (2.45 or 5.8 GHz) RF band where there are minimum losses in the atmosphere. Materials for the satellites are sourced from, and manufactured on Earth and expected to be transported to LEO via re-usable rocket launch, and transported between LEO and GEO via chemical or electrical propulsion. In summary, the architecture choices are: