What you are actually buying: usable kWh
Batteries are sold in volts and amp-hours, but what runs your house is usable kilowatt-hours. A 48 V 100 Ah battery is 4.8 kWh nameplate. A lithium (LFP) pack lets you use roughly 90% of that; a tubular lead-acid bank realistically gives you around half before you start shortening its life.
So two quotations showing the same nameplate can differ by nearly double in real backup. Always ask for usable kWh at the stated depth of discharge, in writing.
Sizing backup for a Karachi home
Start from the loads you actually want during an outage, not the whole house. Fans, lights, fridge, internet and a TV is roughly 400–700 W continuous. Add one inverter AC and you are near 1.2–1.6 kW.
Multiply by the hours you want. Four hours of essentials is about 2.5–3 kWh usable; a night with one AC is closer to 8–10 kWh usable. That number, not the panel size, drives battery cost.
- Essentials only, 4 hours: ~3 kWh usable
- Essentials + fridge overnight: ~5 kWh usable
- One inverter AC overnight: ~10 kWh usable
- Whole-home comfort backup: 15 kWh usable and above
Lithium vs tubular in Karachi conditions
Karachi heat is the deciding factor. Lead-acid capacity and life fall sharply in hot, poorly ventilated store rooms, and the bank needs water top-ups and equalisation. LFP lithium tolerates heat far better, needs no maintenance, and delivers thousands of cycles instead of hundreds.
Tubular still makes sense when the budget is tight and backup is occasional. For daily cycling — which is what most Karachi homes end up doing — lithium costs less per delivered unit over its life even though the sticker is higher.
What changes the price of the same kWh
Cell grade (A-grade prismatic LFP versus reclaimed cells), the battery management system, communication with your hybrid inverter, enclosure quality and whether local warranty support genuinely exists. Imported packs with no service presence in Karachi are cheap until the first fault.
Installation matters too: correct busbar and cable sizing, fusing, ventilation and a mounting location that is not an unventilated rooftop cabin in June.
Getting a real number for your home
We do not quote battery prices blind, because backup hours depend on your loads. Our free Karachi survey records your appliance list and outage pattern, then we size the pack and list cell make, model, usable kWh and warranty terms on the quotation. Call us to book it.
Frequently asked questions
- How long does a lithium solar battery last in Karachi?
- A good LFP pack is rated for several thousand cycles. With daily cycling and correct ventilation, that typically means many years of service, and the warranty should state retained capacity, not just years.
- Do I need a battery if I have net metering?
- No. Net metering already banks your surplus with K-Electric. A battery is for outage backup and for using solar energy at night, so add it only if uninterrupted supply matters to you.
- Can a battery be added to an existing solar system later?
- Usually yes, if the inverter is hybrid or battery-ready. If you have a grid-tie-only inverter, adding storage means changing or adding an inverter, so tell your installer at design stage.