K-Electric buys at the same rate at which it sells you. If K-E selling you a unit for Rs.44 it will buy the same unit for Rs.44. For Lesco its off peak rate.
Minimum you can make 80% of the installed power in worst case scenarios but usually its 90%. So you can make 900 Watts in a day.
So you sell energy in the day time and consume it at night, removes batteries completely. Also, this is very good for businesses because Saturday & Sunday no electricity consumption. So you can sell electricity back to grid and when you start consuming from monday those 2 days units sold will be deducted from the final bill.