Size an off-grid solar system from the load up. Enter what the site actually draws, choose the worst-month sun hours and the autonomy you need, and the calculator returns array size, battery capacity and controller rating using the same method we use for project quotations. No email required, nothing stored.
1. Load audit
| Device | Watts | Hours / day | Qty | Wh / day |
|---|
2. Site and storage conditions
Use the lowest monthly value for your site, not the annual average.
3-4 for accessible sites, 5-7 for remote or monsoon sites.
How this is calculated. Daily energy is the sum of device watts × hours × quantity. Array size applies a 1.25 design margin for ageing and soiling and assumes 0.70 system efficiency (dust, cell temperature, controller and cabling losses): Wp = Wh/day × 1.25 ÷ (sun hours × 0.70). Battery capacity divides daily energy × autonomy days by usable depth of discharge. Controller current uses array watts ÷ system voltage × 1.25, then rounds up to the nearest standard rating.