That's module cost alone, no DC or BOS.

Currently the complete installed price is ranging between the low $4's to $8 installed. Some of the really BIG (100MW and larger) may be in the $3's/watt, but I doubt they'll advertise the actual numbers since that would cut into their profit. When you have 500,000 or more modules the economics of scale takes on a whole new meaning and the builders can practically dictate material prices.