How Many Batteries for a 5kW Solar System?
The battery count depends on your nightly load, not your panel wattage. Here is the usable-kWh math for lithium vs tubular banks, one-day-autonomy examples, and indicative 2026 PKR pricing.
The short answer
A 5kW solar array in Pakistan produces roughly 18–22 kWh per day — but batteries store your nighttime use, so the count comes from your evening load, not the panel rating. The standard answers:
- Evening essentials (fans, lights, TV, fridge — ~4–6 kWh): 4 × 200Ah tubular batteries or 1 × 5kWh LiFePO4 unit.
- Full household through the night (~10–14 kWh usable): 8–12 × 200Ah tubular batteries or 2–3 × 5kWh LiFePO4 units.
The formula behind both: usable kWh = nightly load × autonomy days, then divide by depth of discharge — 50% for tubular lead-acid, 90% for lithium. That single division is where most people undersize their bank by half.
The one formula that matters
Battery labels show nominal capacity — what the chemistry can physically hold. What you can actually use is smaller, because deep-discharging lead-acid destroys it. The conversion:
Usable kWh = nominal kWh × depth of discharge
Bank to buy = usable kWh needed ÷ depth of discharge
A 200Ah 12V tubular battery holds 2.4 kWh nominal — but only 1.2 kWh usable at 50% depth. A 51.2V 100Ah LiFePO4 unit holds 5.12 kWh nominal and delivers about 4.6 kWh usable at 90% depth. Same "one battery," nearly four times the usable energy per unit. Our solar battery size calculator runs this conversion for both chemistries and converts the result to amp-hours at your system voltage.
Battery counts by nightly load
Pick your nightly usable kWh, then read across. Tubular assumes 200Ah 12V units (2.4 kWh nominal each); lithium assumes 51.2V 100Ah wall-mount units (5.12 kWh nominal each):
| Nightly usable need | Tubular 200Ah count | LiFePO4 5kWh count |
|---|---|---|
| 4–5 kWh (essentials) | 4 | 1 |
| 8–10 kWh (most rooms) | 8 | 2 |
| 12–14 kWh (full house) | 12 | 3 |
Notice the 4-to-1 and 4-to-3 ratios: usable depth does almost all the work. The full chemistry comparison — cycle life, maintenance, and 10-year total cost — is in our LiFePO4 vs lead-acid guide.
Worked example: one night of autonomy
Say your household draws 10 kWh after sunset — a realistic full-house figure without heavy air conditioning. Applying the formula:
- Tubular route: 10 kWh ÷ 50% = 20 kWh nominal to buy. At 2.4 kWh per 200Ah battery, that is 8.3 → 8 batteries (19.2 kWh nominal, 9.6 kWh usable).
- Lithium route: 10 kWh ÷ 90% = 11.1 kWh nominal. At 5.12 kWh per unit, that is 2.2 → 2 units (10.24 kWh nominal, 9.2 kWh usable).
Want two cloudy days of autonomy? Multiply everything by two — and notice how fast a lead-acid bank becomes a small warehouse. This is why grid-tied hybrid systems are almost always sized for one night, not three: the grid (or net metering) covers the rare long outage far more cheaply than batteries do.
The 48V wiring rule
Nearly every 5kW hybrid inverter on the Pakistani market expects a 48V battery bank. That dictates how batteries connect:
- Tubular: 12V batteries wire in series strings of 4 (12V × 4 = 48V). You can only buy them in multiples of 4 — 4, 8, 12. A "6 battery" plan is electrically impossible on a 48V inverter.
- Lithium: 51.2V units connect in parallel, so 1, 2, or 3 units all work — far more flexible sizing.
Mixing old and new batteries in one bank is the classic expensive mistake: the weakest battery drags the whole string down, especially with lead-acid. Size once, buy together.
2026 PKR pricing (indicative)
Prices move with import duties and the rupee, so treat these as indicative 2026 ranges from the retail market, not quotes:
| Battery | Usable kWh per unit | Indicative 2026 price |
|---|---|---|
| Tubular 200Ah (tall) | 1.2 | PKR 55,000–80,000 |
| LiFePO4 51.2V 100Ah (5.12 kWh) | 4.6 | PKR 250,000–400,000 |
Bank-level view for the 10 kWh-usable example above: 8 tubular ≈ PKR 440,000–640,000 vs 2 lithium ≈ PKR 500,000–800,000. Upfront, lead-acid still looks cheaper — until you remember the tubular bank gets replaced roughly twice while the lithium bank is still inside its cycle life. Lifetime cost flips the result, as the 10-year comparison shows in detail.
Do you even need batteries?
Honest check before you spend half a million rupees: an on-grid 5kW system with net metering needs no batteries at all — daytime surplus exports to the grid and earns credits against your evening import. Batteries only earn their cost when you need backup during outages or want to run evening loads without buying grid power. If your area's supply is stable and net metering is available, a batteryless on-grid 5kW system has the fastest payback of any configuration.
Budget your evening load first
Before buying a single battery, inventory what actually runs after sunset. Watts × hours ÷ 1,000 = kWh. A realistic Pakistani evening:
| Evening load | Typical draw | 4-hour use |
|---|---|---|
| 4 ceiling fans | 300W | 1.2 kWh |
| LED lights (whole house) | 100W | 0.4 kWh |
| Refrigerator | 150W avg | 0.6 kWh |
| LED TV + receiver | 150W | 0.6 kWh |
| Laptops, chargers, router | 100W | 0.4 kWh |
| Subtotal (no AC) | 800W | 3.2 kWh |
| 1-ton inverter AC (add-on) | 1,200W | 4.8 kWh |
Essentials land at ~3.2 kWh — comfortably inside a 4-battery tubular bank (4.8 kWh usable) or a single 5kWh lithium unit (4.6 kWh usable). Add one inverter AC and you jump to ~8 kWh, which is exactly where the 8-tubular / 2-lithium answer comes from. Two ACs through the night? That is 12+ kWh — the 12-tubular / 3-lithium row. Most "my batteries die by midnight" complaints trace back to skipping this 5-minute inventory, not to bad batteries.
Mind the inverter's discharge limit
Battery count sets not just energy (kWh) but power (kW) — how fast the bank can release it. A 5kW hybrid inverter can demand up to 5,000W from the batteries during an outage, and chemistries handle that very differently:
- Tubular lead-acid: sustained discharge should stay near 0.2C. A 4-battery 48V/200Ah bank gives roughly 40A × 48V ≈ 1.9 kW sustained — fine for fans and lights, but it will voltage-sag under a 5kW surge. This is another reason air-conditioning on battery backup needs 8+ batteries, not just for energy but for current.
- LiFePO4: a 5.12 kWh unit with a 100A BMS delivers about 5.1 kW continuous — one unit can feed the full 5kW inverter output. Two in parallel double the headroom.
Practical takeaway: if your backup plan includes motor loads (water pump, AC compressor), size the bank for both the kWh and the surge kW. The battery size calculator covers the energy side; check the discharge spec against your heaviest simultaneous load for the power side.
5kW battery sizing FAQ
Straight answers, no fluff.
How many batteries do I need for a 5kW solar system?
For evening backup of essentials (fans, lights, TV, fridge — about 4–6 kWh), a 5kW system needs 4 × 200Ah tubular batteries or 1 × 5kWh LiFePO4 unit. For full nighttime household coverage (10–14 kWh usable), double it: 8–12 tubular batteries or 2–3 lithium units.
How many 200Ah batteries for a 5kW inverter?
A minimum of 4 × 200Ah batteries, wired in series for the 48V bank most 5kW hybrid inverters require. That gives 9.6 kWh nominal, 4.8 kWh usable at 50% depth of discharge. Heavier night loads need 8 or 12 in matched series-parallel strings.
Is one lithium battery enough for a 5kW solar system?
One 5.12 kWh (51.2V 100Ah) LiFePO4 unit gives about 4.6 kWh usable — enough for an evening of essential loads on a 5kW hybrid system. It will not run a full house through the night with air conditioning; that takes two or three units in parallel.
How many hours of backup will 4 batteries give on a 5kW system?
4 × 200Ah tubular batteries hold about 4.8 kWh usable. At a 500W evening load (fans, lights, TV, fridge) that is roughly 8–9 hours; at 1,000W it halves to about 4–5 hours. Runtime depends on load, not on the 5kW panel rating.
Can I add more batteries to my 5kW system later?
Yes, within limits: tubular banks expand in strings of 4 (to keep 48V), and lithium units add in parallel — but new batteries should match the age and capacity of existing ones, especially lead-acid. Check your hybrid inverter's maximum battery capacity first.
Do I need batteries if I have net metering in Pakistan?
Not necessarily. An on-grid 5kW system with net metering banks daytime surplus with the grid instead of batteries, which is cheaper and simpler. Batteries only earn their cost if you need backup during load shedding or want to use stored power in the evening.
What size battery bank gives one day of autonomy on 5kW solar?
For 10 kWh of usable storage (one night for a typical household), you need 8 × 200Ah tubular batteries (19.2 kWh nominal at 50% depth) or 2 × 5.12 kWh LiFePO4 units (10.2 kWh nominal at 90% depth). True multi-day autonomy multiplies this — which is why grid-tied hybrid systems usually size for one night, not three.
Size your bank in 60 seconds
Enter your nightly kWh and autonomy days — the calculator handles usable depth, both chemistries, and the amp-hour conversion at your system voltage.