Solar, Storage & Electrification
The 120% busbar interconnection rule, PV string and cold-Voc sizing, rapid shutdown, battery energy storage, heat pump and HVAC circuits, standby generators, energy management systems and whole-home electrification planning.
Solar 120% Busbar Rule Calculator
Calculate max solar backfeed breaker, allowable inverter AC output, and main breaker derate requirements per NEC §705.12(B).
Open calculator NEC 2026 / 2023Solar PV String & MPPT Sizing Calculator
Calculate temperature-corrected max Voc, min/max modules per string, inverter MPPT window, and 156% DC wire sizing per NEC §690.7 & §690.8.
Open calculator NEC 2026 / 2023Solar Rapid Shutdown & MLPE Sizing (NEC 690.12)
Verify rooftop solar rapid shutdown compliance, inside boundary ≤ 80V / outside ≤ 30V rules, and MLPE devices per NEC §690.12.
Open calculator NEC 2026 / 2023Battery Storage / ESS Sizing Calculator
Size residential and commercial battery storage systems (ESS), backup duration runtime, inverter kW, and 125% circuit OCPD per NEC Article 706.
Open calculator NEC 2026 / 2023HVAC & Heat Pump Circuit Calculator
Calculate Minimum Circuit Ampacity (MCA), Maximum Overcurrent Protective Device (MOCP), and wire sizing for AC & heat pumps per NEC Article 440.
Open calculator NEC 2026 / 2023Generator Sizing Calculator
Size standby and emergency generators, motor starting surge kVA, fuel/altitude derates, and transfer switches per NEC Articles 445 & 702.
Open calculator NEC 2026 / 2023Whole-Home Electrification Simulator
Simulate panel capacity for Heat Pumps, EV Chargers, Induction Ranges, and HPWH on 100A/200A panels per NEC 2026 §120.83 & §120.87.
Open calculator NEC 2026 / 2023Smart Panel & EMS Load Calculator
Size automated Energy Management Systems (EMS) and smart panels to add EVSE & heat pumps without panel upgrades per NEC 2026 Art. 130 & §625.42.
Open calculator NEC 2026 / 2023Energy Cost Calculator — Electricity & kWh
Calculate equipment electricity running costs ($/day, $/month, $/year) based on wattage, operating hours, and local utility $/kWh rates.
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