Just How Cheap is Solar in India ?

This article seems to say ~ 1.7 USD a watt (rated capacity) installed. Is my arithmetic correct ? Moreover, the PV owner has entered into a purchase agreement to sell at ~ 8 Rs a Kwh. I'd like to know details, because that sounds like a very spiffy financial return for the owners of the plant*. Just imagine being able to invest in green energy at a stable return competitive with historical stock market results.

*68.077 Rs a watt installed, I presume 1.5 - 2.0 kwh a year production.

Addendum: $ Analysis in Google Doc. Works out to a savings APR equivalent of close to 8.4%.