My electric cost is $0.21/kwh too... 
Discussion
Nice 🙌
what’s your setup ?
This is for one Antminer Z15.
My buddy said one is on the way to me, but I won't believe it until it shows up.
I have 2 S9s running @600w each right now heating my house.
The z15 will be louder, but I'll get paid to heat my mobile home.
Much better than a bullshit 1500w space heater or shelling out $650 for propane + the increased electric bill to run the heater... 🤙
Did you count hardware amortization? Brand new miner should be considered obsolete after 3 years, older one even faster until it cost more to run than what it generate.
You should also compare vs: using the hardware money to buy BTC upfront + electricity money to buy BTC each week/month as DCA. Then you know is mining was (more) profitable.