India is electricity surplus, but many of the new power plants are renewable type which come under non dispatch able category so their production is not always certain
and of course, as you mentioned, DISCOMS ki lagi padi hai :P even in MH, which has one of the finest transmission grid in the country, we have multiple regions in our state where billing efficiency is not even close to 100%!!! no wonder PLF of thermal plants are so low. this affects production further
if you're free, try going through prev year's econ survey's...
more... 2nd chapter, it discusses this topic in some what more detail from financial POV