Ed Hoskins provides a very wide-ranging analysis on the capital costs of renewables in Europe, with information about all the major countries. Despite total investment of $500bn so far, renewables provide just 2.9% of actual power generated. Hoskins also provides some graphical data on “Intermittency and Non-dipatchability” of energy output, helping highlight that renewables are not just expensive, they are also pretty useless at providing power when required.
The one weakness in the analysis is in the costs per unit of output – something outside the main purpose of the post. The source of that data is the U.S. Energy Information Administration. This uses (Table 2-5 on page 44 of the pdf file) “Overnight Capital Cost” which measures capital and maintenance costs per unit of capacity. So, for instance, “Onshore Wind” appears to have only 2.2 times the capital cost of “Natural Gas Advanced Combined Cycle”. But assuming the former operates at 25% of capacity and the latter at 85%, the capital costs of wind power becomes 7.5 times that of gas. Similarly, assuming offshore wind operates at 35% of capacity, relative capital costs rise from 6.2 to 14.8 times that of gas.

http://www.eia.gov/forecasts/capitalcost/pdf/updated_capcost.pdf

Another point is that the EIA does not consider conventional coal-fired power stations, possibly inflating the price by some measure of “The Social cost of Carbon”. Using the average price in AR4 of $12 per tonne of CO2 (Synthesis Report Page 69) and that a coal-fired power station produces about 500kg per megawatt, this $6 per megawatt is trivial compared with the much higher cost of renewables.