In terms of global warming potential (GWP), in comparison to CFCs that have GWP 4,680 — 10,720, HCFCs have lower GWPs (76 — 2,270). (en.wikipedia.org)
By the way, thermal solar power, such as is used in solar hot water, is about 60 to 65 % efficient, and has much lower cost, in terms of global warming gasses, than PVs. (answers.com)
The problem was historically not realizing the ecological impact of producing and burning fossil fuels (both in terms of global warming as well as other forms of pollution) until it was a problem of catastrophic proportions. (treehugger.com)