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About PanelRig

What Is PanelRig?

PanelRig is a free collection of professional-grade solar and energy calculators built for homeowners researching solar, installers quoting jobs, and energy professionals designing systems. Every tool on this site is designed to give you accurate, code-compliant results - not vague estimates.

Whether you're figuring out how many panels you need, estimating your payback period, or checking which tax credits still apply after recent federal policy changes, PanelRig gives you a straight answer with the math to back it up.

Why We Built This

The solar industry is full of calculators that overpromise. Sites that still advertise a "30% federal tax credit" even though the residential ITC expired at the end of 2025. Tools that don't account for system losses, panel degradation, or real-world conditions. Marketing pages disguised as calculators.

We built PanelRig because professionals and homeowners deserve better. Every formula on this site is transparent, every assumption is stated, and every regulatory reference is fact-checked against current law and code. When the One Big Beautiful Bill Act eliminated the residential solar tax credit in July 2025, we updated our tools the same week - while most competitor sites still haven't.

Our Standards

Every PanelRig calculator is built against real engineering standards and current regulations:

  • NREL PVWatts methodology - our solar output calculations use the same approach as the National Renewable Energy Laboratory, including 14% default system losses covering inverter efficiency, wiring, soiling, shading, snow, and degradation
  • IRS code references - tax credit calculations cite specific Internal Revenue Code sections (25D, 48, 48E) and reference the actual legislation (Inflation Reduction Act 2022, One Big Beautiful Bill Act 2025) that governs eligibility
  • EIA data - electricity rate and escalation assumptions are based on U.S. Energy Information Administration historical data, not guesses
  • NEC 2023 compliance - electrical calculations follow the National Electrical Code where applicable

How We Keep Things Accurate

We run automated accuracy tests on every calculator monthly. Each test verifies:

  • Math accuracy - independent Python calculations cross-check every formula against known test cases
  • Regulatory currency - automated web searches verify that our tax credit, incentive, and code references match current law
  • Live UI verification - a browser bot enters test values into every live tool and confirms the displayed results match expected outputs

If any test fails, the tool is flagged and corrected before the next business day.

Affiliate Disclosure

PanelRig is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Some pages include product recommendations with affiliate links - these are clearly labeled and do not affect our calculator results or editorial content. We also display ads through Google AdSense.

Our calculators are and always will be 100% free. Affiliate commissions and ad revenue help us keep them that way.

What We Don't Do

  • We don't sell leads to solar installers
  • We don't collect or store your calculator inputs - everything runs client-side in your browser
  • We don't require signups, accounts, or email addresses to use any tool
  • We don't inflate savings estimates to sell you on solar

Our Tools

PanelRig currently offers the following free calculators, with more added regularly:

Contact

Questions, corrections, or suggestions? Reach us at contact@panelrig.com.

Found an error in one of our calculators? We want to know. Accuracy is our #1 priority.