My 4x5830 rig draws 650 watts and outputs 1112 mhps which generates .64 btc and draws 15.6 kwh.
.15 for 9 hours and .08 for 15 hours is about .11 per kwh average per day.
Cost to generate btc is $2.59 per coin.
Your setup computes 1.71 Mhash/Joule. Although there is a lot of invalid data in
https://en.bitcoin.it/wiki/Mining_hardware_comparison your claim is inconsistent with the wiki which puts the value anywhere between 1.3 and 1.6 Mhash/Joule.
How did you measure 650W? Do you under/overclock the GPU or memory? Etc.