From what I can find, the best rate you'll pay in Sweden for electricity is about 8 eurocents per kWh, which isn't very good. That's what large mines and data centres pay.
KnCMiner, based in Stockholm, operates about 7,000 machines. While the mining companys electric bill in March came to $450,000, the computers mined 21,000 bitcoins, according to co-founder Sam Cole.
http://www.businessweek.com/news/2014-04-11/bitcoin-mining-boom-sputters-as-prospectors-see-real-cash-losses21000x$600 = $12,600,000
$12,600,000 - $450,000 = $12,150,000
Do not, ever, in any way, feel sorry for these c@ck-suckers.
Well, according to
organofcorti's blog KnC found about 12,000 bitcoins in March so unless they were hiding hashrate that 21000 doesn't seem right.
Regardless, according to ooc their average hashrate in March was ~3630TH/s. Say 1J/GH, and that's 2.7GWhr in March. $450,000/2.7GWh = $0.167/kWh. Obviously there's some pretty decent error bars there, but even if you said they had enough hashrate to mine (let's say 6500TH/s)
BTC21000, that's $0.095/kWh.