Hardware purchase price gets the attention, but your commercial electricity contract determines whether a mid-range yard is viable over a full season. We review power agreements as part of every site assessment because the fine print — demand charges, time-of-use windows, and power-factor penalties — can erase hash-rate margins faster than a fan failure.
Demand Charges vs Energy Charges
Most commercial contracts in South Korea bill both energy (kWh consumed) and demand (peak kW drawn during a billing interval). Mining yards create flat, high demand profiles. A row of 50 units at 0.12 TH/s each might draw 150–180 kW continuously — and your demand charge is set by the highest 15-minute peak in the month.
Operators who boot all machines simultaneously on the first of the billing cycle often spike demand unnecessarily. Staggered startup over 30–45 minutes can reduce the recorded peak by 10–15% without affecting total monthly hash output.
Time-of-Use Windows
Some industrial tariffs offer lower energy rates during off-peak hours (typically 22:00–08:00). Mid-range ASICs do not pause gracefully — they run continuously or not at all. If your contract has meaningful off-peak discounts, the math favours running full capacity overnight and accepting slightly higher rates during peak afternoon hours only if you throttle (which reduces revenue).
We model three scenarios in our assessment reports: flat run, peak-throttle, and staged startup. The best choice depends on your specific tariff schedule and ambient cooling costs.
Three-Phase Balance
Unbalanced loads across L1, L2, and L3 phases trigger penalties on some commercial accounts. Rack layout matters: clustering all power supplies on one phase because it is closer to the panel creates imbalance even when total amperage is within limits.
Our electrical planning includes a phase-allocation map showing which rack positions connect to which leg. Commissioning crews verify balance with clamp-meter readings before signing off.
Power Factor and Harmonics
Large fleets of switch-mode power supplies can degrade power factor. Utilities may assess surcharges when power factor drops below 0.9. Adding power-factor correction capacitors at the panel is a one-time cost that pays back within months on yards above 100 kW demand.
Before You Sign a Hardware Purchase Order
Request a copy of your last three commercial electricity bills. Note the demand peak, energy consumption, and any penalty line items. Share these with us during the assessment — we incorporate tariff structure into the maximum safe unit count recommendation.
A yard sized to your panel but ignoring demand-charge mechanics will underperform on paper and overperform on your KEPCO invoice.