All Tools
Every solar calculator.
Free, no sign-up, every formula shown. Pick the tool that matches your setup — RV, off-grid cabin, home rooftop, battery bank, payback math, or EV charging.
RV Solar Sizing
Size your panel array, battery bank, and charge controller for van life or RV travel.
↳ 500 Wh/day, 5 sun hrs → 125W panels
Off-Grid Cabin System
Full off-grid system design: panels, batteries, inverter size, and estimated cost range.
↳ 3 kWh/day, 3 days backup → 4.4 kW system
Home Solar Savings
Annual savings, payback period, and 25-year ROI — with your state's sun hours and utility rates.
↳ $150/mo bill in TX → 7.2 yr payback
Battery Bank Sizing
Size a battery bank for backup or off-grid use — DoD, voltage, chemistry, and string layout.
↳ 5 kWh/day, 3 days, 48V → 6 × 100Ah
Solar Payback & ROI
Simple payback, IRR, NPV, and 25-year savings chart — with federal and state incentives.
↳ $18K system, 30% ITC → 8.4 yr payback
Solar + EV Planner
Extra panels needed to cover EV charging, fuel savings vs. gas, and annual charging cost.
↳ 200 mi/wk → +3 panels, $1,400/yr saved