NerdVolt tools
Solar, battery, backup, and wiring calculators.
Use these transparent calculators to size systems, estimate runtime and savings, and sanity-check equipment decisions. The formulas are shown on each page so you can audit the assumptions.
Accuracy rule
Exact math, honest estimates.
Watts, kilowatts, kWh, runtime, and voltage-drop formulas are deterministic. Solar output, savings, incentives, tax logic, and emissions depend on local data and should be treated as planning estimates.
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Defaults are visible and editable. Use manufacturer datasheets and local tariff/code data for final decisions.
CalculatorSolar System Size CalculatorEstimate the solar array size and panel count needed to offset your annual electricity use.CalculatorSolar Production EstimatorEstimate monthly and annual solar energy production from array size and solar-resource assumptions.CalculatorBattery Backup Runtime CalculatorEstimate how long a battery can run critical home loads during an outage.CalculatorBattery Bank Sizing CalculatorSize a battery bank from daily load, autonomy days, DoD, efficiency, and module size.CalculatorInverter Size CalculatorEstimate continuous inverter watts, surge watts, and DC battery current.CalculatorSolar Charge Controller CalculatorCheck MPPT/PWM controller current and cold-weather PV voltage limits.CalculatorSolar Panel String Sizing CalculatorEstimate max and min modules in series from cold Voc and hot Vmp limits.CalculatorWire Voltage Drop CalculatorEstimate voltage drop, percentage drop, and power loss for copper or aluminum conductors.CalculatorSolar Payback & Savings CalculatorEstimate simple payback, first-year savings, and 25-year net present value for a solar project.CalculatorSolar Tax Credit Eligibility CheckerCheck basic U.S. residential clean energy credit timing and estimate the credit amount from eligible costs.CalculatorState & Utility Solar Incentive FinderFind the authoritative DSIRE directory for solar, storage, efficiency, and net-metering incentives.CalculatorSolar CO₂ Savings CalculatorEstimate avoided carbon dioxide emissions from annual solar generation.CalculatorEV Charging Solar CalculatorEstimate EV charging energy, charger power, charge time, and added solar size.CalculatorCritical Loads PlannerPlan daily backup energy, peak running watts, and surge watts for must-run outage loads.