Installed capacity growing, generation not at par !

The total installed capacity worldwide is over 120 GigaWatts now. US, Germany and China , each are adding 5000 MW every year.Europe is still number one followed by US and Asia in terms of total installed capacity.
This huge capacity of 120 GW can produce over 250 Terawatthours(TWh)in a year. Theoritically so.
THe avrage PLF in India is just 15%. Global average PLF is 30 %. Why so? We have incentives for installing,not for generation.