I am trying to get into the heads of the ASIC manufacturer/miners and draw some conclusions about where they think mining is going. To that end I built a tool where I could model various scenarios. This run is focused on power consumption verses when the device could go into production. Most of the relationships are linear, so you can insert your own assumptions for BTC$, efficiency, power cost and days per difficulty bump.
The first column is the number of difficulty bumps from the start (which is current difficulty). At 12 days per bimp, this is 48, 96 and 144 days. It reflects when new equipment might go into production.
Second column is difficulty
Third column is always one tera-hash
Forth column is the Kilowatts for 1 tera-hash
Fifth column is the BTC conversion. This is used to compute the power crossover point.
Sixth column is an efficiency factor. It assumes the one terahash is not always available.
Sixth column is the cost per kilowatt hour of electricity
Seventh column is the increase in difficulty with each bump. It has been running 16% in 2014
Eighth column is the number of days between bumps. This has been running 12.1 in 2014
Last column is the dependent variable - it is the number of days until the miner goes negative on power cost.
There are four groups of starting difficulty under the 15% & 12 day assumption: today, 48 days from now, 96 days from now and 144 days from now.
Interpreting the table:
If you put a one tera-hash miner in production today that consumed one kilowatt per tera-hash, it would remain profitable for 153 days.
If you put a one tera-hash miner in production in 48 days that consumed one half kilowatt per tera-hash, it would remain profitable for 165 days.
If you put a one tera-hash miner in production in 144 days that consumed one quarter kilowatt per tera-hash, it would remain profitable for 128 days.