Decision workspace
One plan that keeps your numbers
Save scenarios, compare outcomes, share an address-safe link, and print a homeowner-ready report.
Open my solar planFree solar calculators. Know your numbers before you call an installer.
Free, transparent solar calculators and a source-linked incentive database for US homeowners. Production estimates use NREL PVWatts® with the assumptions shown - no email required.
Free, unlimited calculations. No account, email gate, or calculation credits required.
Updated for 2026: the 30% federal solar tax credit for homeowners ended on Dec 31, 2025. Verify eligibility with the IRS before assuming a federal credit in a cash or loan proposal. See what changed →
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.
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
What do you want to calculate?
Start with one question. Each tool explains its inputs, a worked example and what to verify.
Proposal intelligence
Compare up to three installer quotes
Normalize total payments, price per watt, production, equipment, batteries, and warranty coverage.
Compare solar quotesPrimary-source research
Check the utility rule behind savings
Review billing models, tariff questions, source dates, and official utility verification links.
Browse utility guidesSystem Size Calculator
Turn your annual kWh usage into the right solar system size in kW.
Open tool →Solar Savings Calculator
25-year savings, payback, ROI, and NPV with up-to-date 2026 tax rules.
Open tool →Incentive Finder
Search federal, state, and utility solar incentives by state.
Open tool →Solar planning in plain English
The four numbers to check before comparing solar quotes
A useful solar estimate connects your electricity use, local sunlight, installed price, and utility export policy. Wattcrunch keeps those assumptions visible so you can change them instead of trusting a hidden sales estimate.
01
Annual electricity use
Use 12 months of bills in kWh. Square footage alone cannot size a solar system accurately.
Calculate system size02
Local solar production
A 1 kW array produces different amounts by location, roof direction, tilt, and losses. We use NREL PVWatts for address-based estimates.
Check solar potential03
Installed price per watt
Compare quotes before financing. Equipment, roof work, batteries, and dealer fees should be separated clearly.
Check a solar quote04
Import and export rates
Retail electricity avoided on-site can be worth more than exported solar. Net metering and time-of-use rules materially change savings.
Model net meteringWant to audit the assumptions? Read our calculator methodology and editorial policy.
Transparent by design
See the assumptions before you trust the answer
Wattcrunch is an independent planning resource, not an installer, lender, utility, or tax adviser. We show the inputs, formulas, source hierarchy, and planning ranges so you can challenge an estimate instead of accepting a hidden sales calculation.
Policy
Utility, government, DSIRE, and IRS references for incentive and tariff checks.
Browse utility guidesLearn how Wattcrunch creates and checks its content in the editorial team profile.
