Here's another example of the capacity factor of windmills. Next time you see a number of MW advertised, you can safely divide it by 4.
This means that a 10MW wind farm plant like this one in India, will give you this 10MW 25% of the time or just 2.5MW in average. According to this article, this capacity factor is very good. Look at the months of March and April, it looks like the capacity factor is under 10%. Therefore you definitely need another source of power to compensate. Nuclear seems the best choice for them in India.
Full article from the PDF:
Nuclear Power Corporation of India Limited (NPCIL)has a wind farm in operation at Kudankulam Nuclear Power Project (KKNPP) since January 2007.
For the second year in succession since its inception, KKNPP wind farm has performed exceedingly well in terms of generation of electricity in the financial year 2008-09. KKNPP wind farm, consisting of eight 1.25-MWe wind turbine generators (WTGs), became operational on January 24, 2007 and since then, it is in commercial operation, generating electricity through wind power.
The power thus generated is being fed to Tamil Nadu Electricity Board (TNEB) grid, earning revenue for NPCIL. In the year 2007-08, KKNPP wind farm generated 22.423 Million Units with a plant load factor (PLF) of 25.53%, and quite significantly, there is an improvement in the performance of wind farm in the year 2008-09. Generation of 22.996 MUs is higher by 2.56% compared to the generation of previous financial year (2007-08). Plant load factor of 26.25%, achieved in 2008-09 is better than the average PLF achieved in the region.
KKNPP wind farm turbine generators have been among top-performing generators in the region. This is attributable largely due to better windy conditions that prevailed in the year 2008-09 when compared to 2007-08 and also, to some extent, due to improvement seen in the machine and grid availability around this time.