Attached are the details of the electrical use, all boils were 60 min with 10 min mash out (one brew early in the day and then the other two from 6pm to 2am). The first one set the strike water from around 13 to 65 deg C, the second two I used hot water to start so it didn't have to increase the temp much (which makes the true cost a little off).
The hot water heater electrical use during the brews was slightly higher, but would have been any hot water in the house, so I can't directly attribute it to the brew session, but final best guess answer to the cost of an electrical brewing session would be somewhere in the region of $1.50 including hot water heater and a 220v Grainfather.
Cheers!