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Guided Workflow

Step 1 of 9. Follow the sequence to turn a rough idea into a homeowner-ready solar plan.

Next step
  1. 1Size
  2. 2Production
  3. 3Savings
  4. 4Payback
  5. 5Financing
  6. 6Compare
  7. 7Incentives
  8. 8Quotes
  9. 9Report

Solar Calculators

17 free tools — from system sizing to TOU optimization, EV charging, backup loads, quote checking, and shading analysis. Each tool shows its assumptions so you can review the inputs behind the estimate.

Start Here

Build your solar plan in one guided flow

Enter your household basics once. We’ll carry them through system sizing, solar production, savings, financing, and incentives so you don’t keep retyping the same assumptions.

kWh/yr
$/kWh
$/W

Use real bill history

Import a text-based PDF, CSV, or text export with monthly kWh. Files are processed in memory and are not retained.

Start the guided planBrowse all toolsOpen my plan

What the workflow answers

  • How big your system should be
  • How much your roof can produce
  • What solar is likely to save you
  • Whether cash, loan, or lease looks better
  • Which incentives still matter in 2026

Core Tools

The fundamentals — every homeowner should run these before signing anything.

System Size Calculator

kWh usage → kW system, panel count, roof area.

Open →

Solar Savings Calculator

25-year savings, payback, ROI, NPV.

Open →

Solar Potential (by address)

Address → NREL PVWatts production estimate.

Open →

Payback / ROI Calculator

Break-even year and return on investment.

Open →

Net-Metering Estimator

Self-used vs exported energy at full retail or net-billing rate.

Open →

Bill Savings Estimator

Your new monthly bill after solar.

Open →

Solar Loan Calculator

Monthly payment, total interest, ITC paydown.

Open →

Lease vs Buy vs PPA

Compare all four ownership paths over 25 years.

Open →

Battery Storage Sizing

kWh of backup needed from your loads.

Open →

✨ New Tools

Tools no other solar calculator site offers.

New

TOU Rate Optimizer

Model solar + battery under time-of-use electricity rates. See peak arbitrage value.

Open →New

Solar + EV Calculator

How much larger your system needs to be to charge your EV for free.

Open →New

Backup Load Sizer

Select appliances → exact kWh needed and Powerwall runtime.

Open →New

Quote Fairness Checker

Is your solar quote fair? Compare $/W to your state's 2026 market median.

Open →New

Shading Loss Estimator

How much do trees or chimneys cut output — and is a microinverter worth it?

Open →New

Solar + Heat Pump

How much extra solar to cover a heat pump replacing gas or oil heat.

Open →New

Carbon Impact Calculator

CO₂ offset, trees equivalent, car miles avoided over 25 years.

Open →

⚠ 2026 accuracy note

The federal residential solar tax credit (Section 25D) expired December 31, 2025 under Public Law 119-21. All Wattcrunch calculators reflect this — homeowner-owned systems placed in service after December 31, 2025 receive $0 federal credit. Review the IRS guidance and confirm tax treatment with a qualified professional.

Embed Wattcrunch on Your Site

Writing about solar? Give your readers an interactive calculator without leaving your page. Wattcrunch calculators are free to embed — no API key, no sign-up required.

System Size Calculator

kWh usage → kW system size, panel count, roof area.

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  src="https://wattcrunch.tech/calculators/system-size"
  width="100%"
  height="640"
  frameborder="0"
  loading="lazy"
  title="Wattcrunch Solar Calculator"
></iframe>
Preview this calculator →

Solar Savings Calculator

25-year savings, payback period, ROI, NPV.

<iframe
  src="https://wattcrunch.tech/calculators/solar-savings"
  width="100%"
  height="640"
  frameborder="0"
  loading="lazy"
  title="Wattcrunch Solar Calculator"
></iframe>
Preview this calculator →

Solar Payback Calculator

Break-even year and lifetime return on investment.

<iframe
  src="https://wattcrunch.tech/calculators/payback"
  width="100%"
  height="640"
  frameborder="0"
  loading="lazy"
  title="Wattcrunch Solar Calculator"
></iframe>
Preview this calculator →

Quote Fairness Checker

Is this solar quote fair? Compare to your state's market median.

<iframe
  src="https://wattcrunch.tech/calculators/quote-checker"
  width="100%"
  height="640"
  frameborder="0"
  loading="lazy"
  title="Wattcrunch Solar Calculator"
></iframe>
Preview this calculator →

Attribution link to wattcrunch.tech is included automatically. For custom sizing or a different calculator, contact us.