About SolarCalculatorHQ

SolarCalculatorHQ exists to give homeowners, DIY installers, and curious tinkerers free, accurate solar calculators that don't bury answers behind a lead form. Every tool on the site returns an instant result. No signup. No email harvest.

What we build

Each calculator is built around a real engineering or financial formula derived from primary sources — not copied from competitor sites. We focus on the questions homeowners actually ask before buying solar:

• What's the optimal tilt angle for my latitude?
• What size wire do I need for my off-grid run?
• How long will my batteries take to charge from a given panel array?
• What payback period can I expect for a residential install?

We add new calculators continuously — the goal is comprehensive coverage of every reasonable question a residential or small-commercial solar buyer might have.

Our sources

Cost data comes from publicly available 2026 industry sources we cross-reference for consistency:

• SEIA Solar Market Insight — quarterly US installation cost benchmarks
• EnergySage Marketplace — current installer quotes by state
• NREL (National Renewable Energy Laboratory) — irradiance and TMYP datasets
• DOE Solar Energy Technologies Office — federal cost trends

Engineering formulas (tilt-angle optimisation, voltage drop, ampacity, slope factor) come from primary references including the National Electrical Code (Article 690), ASHRAE Handbook (Solar Energy chapter), and standard photovoltaic engineering texts. Where a formula is a rule of thumb rather than first-principles math, we say so on the calculator's page.

Our limits

Calculators give you an estimate, not a quote. Site-specific factors — shading, roof condition, electrical service, local permitting, utility rate structures — affect every real installation. Always confirm with a licensed installer before purchasing equipment or signing a contract.

We are not a solar installer, broker, or financing provider. We don't sell panels, run referral programmes for installers, or capture leads. The site is supported by display advertising.

Contact

Questions, corrections, or suggestions for new calculators? Email contact@solarcalculatorhq.com or use the contact page.

Updates

Page updates carry visible "Last updated" dates. We refresh cost data quarterly and revisit formula pages when underlying standards change (NEC code cycles, new ASHRAE editions). If you spot a number that looks wrong, please tell us.