[me1010]

8760 hours = 1 year

So...

a 1 Watt device running 24x7 = 8.760 kWh

billed at about $0.40/kWh [includes both generation and delivery and normal for NE USA - ain't deregulation great?!] ~ $3.50 per year.

In order to get to $1.00, total cost per kWh must be about $0.114 ...

[voltagex_]

Thanks, turns out I've had the wrong maths for this in my head for years!