NerdVolt tools

Solar, battery, backup, and wiring calculators.

Use these tools to size systems, estimate runtime, compare payback assumptions, and check basic electrical planning numbers. Each page explains what the inputs mean, how the method works, and what the result cannot decide for you.

Start with solar sizingEstimate backup runtime
How to read a result

Arithmetic can be exact while the assumptions are uncertain.

Watts, kW, kWh, runtime, string voltage, and voltage drop follow formulas. Solar production, savings, incentives, tax treatment, export credits, and installation details depend on location, equipment, and current rules.

Before you use a calculator

Gather better inputs for a better estimate.

Use utility bills, manufacturer datasheets, measured loads, local solar-resource data, current utility rates, and official incentive information whenever possible.

What the calculators do

They turn your inputs into a first-pass estimate so you can compare scenarios and ask better questions.

What they do not do

They do not replace electrical design, tax advice, utility approval, manufacturer instructions, permitting, or an installer’s site visit.

What to stress test

Try conservative production, lower export credits, higher loads, colder battery conditions, and different equipment sizes.

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Solar sizing and production

Open the calculator, enter your own assumptions, and read the notes below the result before making decisions.

CalculatorSolar System Size CalculatorEstimate solar array size from electricity use, target offset, panel wattage, and local production assumptions.CalculatorSolar Production EstimatorEstimate monthly and annual solar production from system size, local sun, tilt, orientation, and loss assumptions.CalculatorSolar Panel String Sizing CalculatorCheck solar string size against inverter or charge-controller voltage, current, MPPT range, and cold-weather limits.
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Batteries and backup power

Open the calculator, enter your own assumptions, and read the notes below the result before making decisions.

CalculatorBattery Backup Runtime CalculatorEstimate how long a battery may run selected critical loads during an outage, with inverter losses and usable capacity in view.CalculatorBattery Bank Sizing CalculatorEstimate battery bank capacity from daily energy use, autonomy days, depth of discharge, and system efficiency.CalculatorCritical Loads PlannerBuild a critical-load list for backup power by separating essential circuits from high-demand convenience loads.
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Inverters, controllers, and wiring

Open the calculator, enter your own assumptions, and read the notes below the result before making decisions.

CalculatorInverter Size Calculator: Continuous Watts, Surge Watts, and Battery LimitsEstimate inverter size for solar, backup, RV, and off-grid systems by comparing continuous loads, motor surge, battery voltage, discharge current, and safety margin.CalculatorSolar Charge Controller CalculatorEstimate charge-controller size using array watts, battery voltage, charging current, and cold-weather PV voltage checks.CalculatorWire Voltage Drop CalculatorEstimate voltage drop, percentage drop, and power loss for copper or aluminum conductors in solar and electrical circuits.
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Money, incentives, emissions, and EV charging

Open the calculator, enter your own assumptions, and read the notes below the result before making decisions.

CalculatorSolar Payback & Savings CalculatorEstimate simple solar payback using conservative assumptions for cost, production, incentives, export credits, and rates.CalculatorSolar Tax Credit Eligibility CheckerEstimate possible residential clean-energy credit value while keeping eligibility, timing, cost basis, and tax situation separate.CalculatorSolar Incentive FinderThis guide covers Solar Incentive Finder, with attention to current rules, local rates, conservative assumptions, and limits of simple estimates.CalculatorSolar CO₂ Savings CalculatorEstimate avoided grid emissions from solar production while understanding emissions factors, lifecycle impacts, and regional differences.CalculatorEV Charging Solar CalculatorEstimate solar energy needed for EV charging from mileage, vehicle efficiency, charging schedule, and utility-rate assumptions.