Solar calculators
Every solar decision comes down to three numbers: how big a system you need, what it costs installed, and how many years it takes to pay you back. These calculators work through all three using 2026 EIA electricity rates, state-level installed costs, and current DSIRE incentive data — and each one shows the formula it used so you can check it against an installer's quote.
- RV Solar CalculatorSize an RV solar setup in seconds. Get panel wattage, battery Ah, charge controller and inverter sizing using an NEC 690.8 safety margin.
- Solar Panel Estimate CalculatorEstimate your 2026 solar system size, installed cost, payback period, and 25-year savings using current EnergySage and EIA benchmarks.
- Solar Payback Period & ROI CalculatorFind out how long your solar panels take to pay for themselves, with 2026 electricity rates and incentive data for all 50 states plus ROI, IRR, and year-by-year cash flow.
- Solar Panel CO₂ Savings CalculatorEstimate the annual and 25-year CO2 emissions avoided by your PV system, using EPA eGRID 2024 grid emission factors.
- Solar Fuse Size CalculatorSize DC fuses for any PV string, battery bank, or inverter, using Isc and continuous-current NEC 690.9 rules.
- How Many Solar Panels Do I Need?Find how many solar panels you need from your monthly kWh, sun hours, and panel wattage, with roof area and production estimates.
- Solar Pool Pump CalculatorSize a solar-powered pool pump and array. Get required flow, pump wattage, panel size, and dollar savings versus your existing pool pump.
- Solar Loan CalculatorEstimate your monthly solar loan payment, total interest, and net monthly cost — search your country, price it in 95 currencies, on flat or reducing-balance rates.
- Solar Panel Snow Load CalculatorCompute flat- and sloped-roof snow loads with per-anchor shear demand, built on ASCE 7 ground snow values.
- Hybrid Solar System CalculatorSize a grid-tied hybrid solar system: PV array kW, battery kWh, hybrid inverter capacity, and annual self-consumption.
- Solar Tax Credit CalculatorWork out your federal Section 25D residential solar tax credit, your state credit, and how much you can actually claim this year.
- Solar Investment Tax Credit CalculatorEstimate your Section 48E ITC, MACRS depreciation tax shield, and net cost for a U.S. commercial or business solar project.
- Solar Feed-in Tariff Calculator (U.S. Net Metering)Estimate your annual solar export revenue and self-consumption savings, covering NEM 1.0 retail credit and NEM 3.0-style avoided-cost export rates.
Run the solar payback period and ROI calculator first. It takes your state, your bill, and your roof's sun hours and returns a break-even year plus a 25-year cash flow. If the payback is longer than you want to hold the house, none of the sizing detail matters yet.
Use the how many solar panels calculator to convert your annual kWh into a panel count, then the solar panel estimate calculator to turn that system size into an installed 2026 cost for your state. Together they give you the two figures an installer's quote should broadly agree with.
The solar tax credit and solar ITC calculators cover the residential and business credits separately, because they are different sections of the tax code with different rules. The feed-in tariff calculator values your exported energy under full-retail net metering or a NEM 3.0-style avoided-cost rate.
The fuse size calculator applies the NEC 690.8 continuous-current margin, and the snow load calculator works from ASCE 7 ground snow loads. These are sizing checks, not a substitute for a licensed electrician or structural engineer signing off on the install.