Solar Battery Backup Time Calculator
Estimate the backup time of your solar battery during load-shedding.
About the Solar Battery Backup Time Calculator
The Solar Battery Backup Time Calculator gives you a clear, instant answer to a question that usually means digging through tables or guessing — enter your numbers and read the result straight away.
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.
For the most accurate outcome from the Solar Battery Backup Time Calculator, keep the editable rates and defaults up to date with current figures before reading the result.
How to size a solar battery bank
- 1
Enter your night-time energy consumption in kilowatt-hours.
- 2
Enter the battery voltage of your system (usually 48 V for home solar).
- 3
Select the battery type and its depth-of-discharge limit.
- 4
Read the required battery capacity in Ah, updated live.
Frequently Asked Questions
How long will my solar battery last during load-shedding?
Usable = Ah × V × 0.8. A 260 Ah 48 V bank gives ~10 kWh — about 10 hours for a 1,000 W load.
How many batteries does a home solar system need?
A typical Pakistani home with a 5–10 kW hybrid system uses 4–8 batteries of 200 Ah at 12 V (wired for 48 V). Exact numbers depend on night usage — this calculator sizes it precisely.
Lithium or lead-acid for solar?
Lithium lasts 2–3× longer, handles deeper discharge and needs no maintenance, but costs more upfront. For daily cycling (as solar batteries do), lithium is usually cheaper per cycle over its life.