SolarSizer: Off-Grid PV Sizing

SolarSizer sizes solar and off-grid power systems — and shows you the maths behind every number. Built for installers, designers and serious DIY builders who need to check a design on site, without signal and without an account. EVERY RESULT SHOWS ITS WORKING Tap any result to see the formula used, the values that went in, the assumptions applied, and the standard or datasheet each constant came from. If a number cannot be defended, it should not be on your screen — so nothing hides behind a black box. WHAT IT SIZES • Load audit — build a daily energy profile from an appliance list with editable presets, and get simultaneous peak and surge power • Array and string sizing — cold-morning maximum voltage, hot-cell minimum, and the valid string window for your controller or inverter • Charge controller matching — MPPT and PWM, current, voltage window, array limits • Battery bank — capacity for your days of autonomy, discharge-rate checks against the datasheet, and the reverse question: how long will this bank last? • Inverter matching — continuous and surge, with headroom you set • Conductors and protection — ampacity under real conditions, voltage drop, conductor size from your own drop target, and fuse or breaker selection WORKS THE WAY A JOB SITE WORKS • Fully offline. No account, no sign-in, no ads, no analytics. Your projects stay on your device. • Metric and imperial, chosen per project • High-contrast dark theme for outdoor use, large controls for gloved hands • Save projects with named variants so you can compare options for the same site • Export a client-ready PDF report and a plain-text summary, or back up your project files HONEST BY DESIGN SolarSizer performs engineering reference calculations. It is not a compliance certification and it does not replace design review. Default constants follow one named reference profile, every constant can be overridden, and each result shows exactly which values were used. Verify against the code edition your authority having jurisdiction has adopted before installing. When a design cannot work — a string that exceeds your controller's cold-weather voltage limit, a bank that cannot deliver your surge, a conductor that fails ampacity or voltage drop — the app says so plainly and shows the fix, instead of quietly printing a number.