As a result, near-term technology and policy decisions are critically important for leveraging long-term change. But the temporal dimensions of this technological differentiation in energy systems are extremely long. In the medium-term (2030), only modest, niche-market inroads of solar PV into the global energy system are expected. Only by 2100 have scenarios clustered either around relatively small solar PV markets (0-80 EJ), assuming no or low C02 emission constraints and high investment costs, or around relatively large solar PV markets (100-180 EJ), under stringent C02 emission constraints and low investment costs.