Solar planning tools

Solar calculators

Move from energy use to equipment and cost with one connected set of transparent planning tools. Every calculator keeps its inputs, assumptions, and sources visible.

01Size6 tools 02Equip8 tools 03Finance7 tools

Small solar systems and battery programs

Considering a balcony kit? The plug-in solar savings calculator separates electricity you use at home from surplus that may earn nothing. Already have an eligible battery? Compare an actual program offer with the virtual power plant value calculator. Both tools expose the assumptions behind the result.

For rooftop projects, the solar ROI calculator starts without a federal residential tax credit. Use your real installed cost and utility terms, then check any available incentives separately.

Planning stage

Solar system sizing

Turn energy use into array, panel-count, off-grid, or RV planning estimates.

6 tools

Solar Panel Calculator: How Many Panels Do You Need?Estimate how many solar panels you need, required system size, annual production, and nominal panel area from monthly energy use or a bill, ZIP, panel watts, roof orientation, and shading.Solar System Size CalculatorEstimate required solar array kW and annual production from monthly energy use, ZIP, orientation, shading, and visible loss assumptions.Home Backup Power CalculatorPlan battery, inverter, solar, and generator capacity from editable critical loads, outage duration, efficiencies, reserve, and optional recharge.Off-Grid Solar CalculatorAggregate daily loads to estimate off-grid solar array power, battery storage, bank amp-hours, and charge-controller current.RV Solar CalculatorEstimate an RV solar array, battery storage, bank amp-hours, and controller current from an editable list of travel loads.Plug-In Solar Savings CalculatorEstimate balcony and plug-in solar savings from panel power, local yield, shade, self-consumption, electricity rates, and upfront cost with no tax credit.

Planning stage

Solar equipment

Plan storage, controller, inverter, cable-loss, angle, and portable-power requirements.

8 tools

Solar Battery CalculatorEstimate solar battery energy, amp-hours, autonomy, and a series-parallel unit count from daily use and visible storage assumptions.Battery Bank CalculatorCalculate series/parallel battery quantity, bank voltage, amp-hours, and watt-hours from unit specifications.Solar Panel String & MPPT CalculatorCheck a solar panel series/parallel layout from module values, temperature, MPPT voltage, maximum PV voltage, and inverter or controller input-current limits.Solar Charge Controller CalculatorCalculate minimum controller charge current and cold-weather PV input voltage from array watts, panel Voc, series count, temperature, and bank voltage.Inverter Size CalculatorAggregate running and surge loads, then apply your own headroom and efficiency assumptions.Solar Cable Voltage Drop CalculatorCalculate resistive DC voltage drop and cable power loss between solar-system components.Solar Panel Angle CalculatorEstimate a fixed or seasonal solar-panel tilt from latitude and compare the direct-beam geometry at an entered installation angle.Portable Power Station CalculatorEstimate portable power-station capacity, runtime, and recharge time from an AC load, daily hours, trip length, usable efficiency, and charging input.

Planning stage

Solar financial calculators

Compare solar ROI, payback, savings, loans, ownership options, and commercial project assumptions.

7 tools

Solar ROI CalculatorEstimate solar production first, then show dated simple ROI, payback, and net savings from visible cost, rate, escalation, and degradation inputs.Solar Savings CalculatorEstimate annual solar production, first-year bill offset, and long-term simple savings from visible usage, system, rate, and degradation inputs.Solar Payback CalculatorEstimate solar production independently, then calculate simple payback from visible installed cost, energy use, rate, escalation, and degradation.Solar Loan CalculatorEstimate a solar loan payment, dealer-fee-adjusted principal, total payments, bill comparison, and an optional verified principal lump sum.Solar Lease vs Buy CalculatorCompare nominal 25-year cash, loan, lease, PPA, and utility-baseline payments from visible user assumptions.Commercial Solar CalculatorEstimate commercial solar production, first-year energy value, operating value, and an optional user-confirmed MACRS depreciation scenario.Virtual Power Plant Value CalculatorCompare a virtual power plant offer using annual payments, battery event energy, recharge costs, wear allowance, and fees to estimate net annual value.

Small solar systems and battery programs

Get notified when solar incentives change in your state.