Solar Battery Backup Time Calculator

Battery storage is the difference between a solar system that works only in daylight and one that powers your home through the night. This Solar Battery Backup Time Calculator sizes the battery bank for your solar system from your night-time energy needs.

The calculation converts your night-time load into the battery capacity required, using the standard relationship between watt-hours, battery voltage and amp-hours, with a depth-of-discharge allowance.

For hybrid solar systems in Pakistan, batteries typically cover 3–8 hours of night load. Sizing them correctly matters: too small and you are back on the grid by midnight; too large and you wasted money on capacity you never use.

Choose between lead-acid (cheaper, shorter life, 50% discharge limit) and lithium (pricier, longer life, deeper discharge). The calculator's depth-of-discharge input lets you model both.