Solar Battery Backup Calculator
Estimate how many hours your solar battery provides as backup.
About the Solar Battery Backup Calculator
The Solar Battery Backup 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 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.
Use the Solar Battery Backup Calculator as often as you like — it is free, needs no account, and pairs well with the other calculators in this category for a fuller picture.
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 does a 12 kWh solar battery last?
Usable energy ≈ capacity × 0.8. A 12 kWh battery powers a 1,500 W load for about 6.4 hours.
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.