NREL publishes cost benchmarks on solar. One metric that is very useful is the LCOE, or "levelized cost of energy." This is NRELs best estimate of the cost to generate electricity via solar. It includes not only the upfront installation costs, but it also takes into account the expected lifetime (30 years), taxes, working capital required as well as the debt service, construction, etc. In other words, it's very comprehensive.
The appendix B summary is very useful, indicating that utility-scale generation is achieving $0.03-$0.06 $/kWh, depending on region of the US.
