The carry trade framing is sharp. You're basically long BTC/USD with negative cost basis on the energy portion that was getting burned for heat anyway. That's a real edge most mining ROI calculators completely miss because they assume the electricity had zero alternative use.

One thing worth flagging: your 31% heating discount math implicitly competes against a heat pump, not just a resistive heater. A decent air-source heat pump in Nordic conditions pulls a COP of 2.5-3.0 even at -10C, meaning 1 kWh of electricity gives you 2.5-3 kWh of heat. So the honest comparison is whether that 31% sats cashback on resistive heating beats the 60-67% energy savings of a heat pump. At current difficulty and price, the heat pump probably wins on pure economics, but you're stacking sats and contributing hashrate, which the heat pump never does.

The Storm Fern observation is the part that doesn't get enough attention. When half the network drops off and your difficulty-adjusted share temporarily doubles, that's the Nash equilibrium working exactly as designed. Home miners are the long tail that keeps running through storms, power outages at industrial facilities, and political crackdowns. That geographic distribution is the thing that makes the difficulty adjustment antifragile rather than just resilient.

Curious about the night rate opportunity. 35% discount for 8 hours means you could theoretically run level 4-Heat during off-peak and drop to level 1-2 during peak pricing. Has 21 Energy built any scheduling into the firmware, or are you manually toggling?