Off-Grid Solar Calculator

You are about to spend real money on batteries and panels. Work out what the system actually needs first. Start with what you run. Pick fridges, fans, lights, a laptop or a kettle from a list of typical appliances (check your own labels) or type your own watts, hours and start-up surge. The app turns that into watt-hours a day, peak load and surge. Then it walks you through the rest, one step at a time. Battery bank: LiFePO4, AGM or flooded, days of autonomy, and a series and parallel layout for the battery you plan to buy. Solar panels: peak sun hours for 100 places worldwide, worst month or any month, or type your own. Charge controller: MPPT or PWM, with the cold-weather panel-voltage check. Inverter: continuous and surge rating with headroom. DC cable and fuse sizes for every run. A live summary bar keeps the totals in view, and a PDF report lists every assumption. Free: loads and battery sizing for one project, for as long as you like. Pro: panels, controller check, inverter, cables and fuses, unlimited projects, duplicate and compare two builds, and the PDF report. Pro is a yearly plan with a free trial, or a lifetime purchase. Nothing leaves the phone. The app asks for no internet and no location permission, and there is no account. Sun data: NASA POWER. These are planning estimates. High-voltage and grid-tied systems need a qualified installer and must follow local electrical code. The app does not certify or approve any installation, and it does not cover grid-tied design.

First release. Size an off-grid solar system step by step: loads, battery bank, panels from peak sun hours, charge controller with the cold-weather voltage check, inverter, and DC cable and fuse sizes. Save several projects and export a PDF report that lists every assumption.