What Size Inverter & Battery Do You Need for Your Home (2BHK/3BHK)?
Wondering what size inverter and battery you need for your 2BHK or 3BHK home? The answer depends on your appliances, how long you want backup, and whether you're running an AC. Below is a practical sizing guide for typical Indian homes, plus our free calculator that handles the math for your exact setup.
The right inverter size isn't a guess: it's the sum of your appliances' running watts plus their startup surges, divided by backup hours you want. Most Indian homes fall into two camps: 2BHK (3–5 kVA) and 3BHK (5–10 kVA). But the real answer lives in your appliance list.
Typical 2BHK home inverter & battery setup
Appliances on backup: Lights, fans, TV, WiFi router, fridge, water pump, microwave, washing machine.
AC on backup? Not usually (puts the system over budget). If yes, upgrade to 5 kVA.
| Inverter size | Battery capacity (Ah) | Backup time (no AC) | Cost (lithium approx.) |
|---|---|---|---|
| 3 kVA (24V) | 100–150 Ah | 4–6 hours | ₹2.5–3.5 L |
| 3.5 kVA (48V) | 50–75 Ah | 5–7 hours | ₹3–4 L |
| 5 kVA (48V) | 100 Ah | 6–8 hours (or AC for 2–3) | ₹4–5 L |
Typical 3BHK home inverter & battery setup
Appliances on backup: All 2BHK items + larger fridge, multiple ACs, extra lighting, electric geyser (selectively).
AC on backup? Yes — one 1.5 ton AC during peak hours is the norm.
| Inverter size | Battery capacity (Ah) | Backup time (with 1 AC) | Cost (lithium approx.) |
|---|---|---|---|
| 5 kVA (48V) | 100–150 Ah | 2–3 hours (AC only) | ₹4.5–5.5 L |
| 7.5 kVA (48V) | 150 Ah | 3–4 hours (AC + lights/fans) | ₹5.5–6.5 L |
| 10 kVA (48V) | 200+ Ah | 4–6 hours (AC + full house) | ₹7–8.5 L |
⚡ Don't guess — calculate: instead of adding these up by hand, use our free Inverter & Battery Backup Calculator — tick the appliances you actually want on backup, set your desired backup hours, and it returns the exact inverter size, voltage, battery Ah and real backup time based on lab discharge tests.
Three questions to size your system right
1. What appliances run on backup?
List everything: lights, fans, fridge, TV, pump, microwave, washing machine, AC (yes/no). Don't include geysers, irons, or heaters — they drain batteries too fast. Our guide to which appliances an inverter runs has typical wattages.
2. How long do you want backup?
4 hours? 6 hours? All night? The longer you want, the larger your battery. A 3 kVA system with 100 Ah gives ~5 hours backup for a typical 2BHK load (lights, fan, fridge, TV); a 200 Ah bank stretches it to ~10 hours. The calculator handles this.
3. Is an AC on the backup list?
This is the biggest deciding factor. An AC (1–1.5 ton) draws 1500–1800 W, so you need at least a 3.5–5 kVA inverter to carry it. Without AC, a 3 kVA system covers most 2BHK homes. See our guide on which inverter runs a 1.5 ton AC for details.
Why lithium beats lead-acid for home backup
If you're sizing a system today, choose lithium (LiFePO4). Here's why:
| Feature | Lithium (LiFePO4) | Tubular lead-acid |
|---|---|---|
| Usable capacity | ~95% (you can use almost all) | ~50% (deep discharge = damage) |
| Voltage under load | Stays stable (better for AC) | Drops sharply (inverter shuts off) |
| Charge time | 2–3 hours | 6–8 hours |
| Lifespan | 4000–5000 cycles (~10 years) | 800–1000 cycles (~3–4 years) |
| Cost per kWh | ~₹8000–10000 | ~₹15000–20000 (over its life) |
See our detailed comparison of tubular vs lithium batteries and the best lithium inverter in India.
A worked example: 3BHK with 1.5 ton AC
Appliances on backup:
- Lights (8 × 15W) = 120 W
- Ceiling fans (3 × 70W) = 210 W
- TV + WiFi = 100 W
- Fridge = 250 W (cycles on/off)
- 1.5 ton AC = 1500–1800 W (startup surge 3–5×)
- Pump (if mains fails) = 750 W (startup surge heavy)
Total continuous: ~3330 W (AC + fridge + fans + lights). Surge: AC startup pulls 4500–6000 W.
Inverter needed: At least 7.5 kVA (7500 W continuous, surge-rated for 5× multiples).
Battery for 3 hours AC backup: AC averages ~1.5 kW; add fans/lights ~0.4 kW. Total ~1.9 kW. For 3 hours: 1.9 kWh needed. A 48V 150 Ah lithium bank (7.2 kWh × ~85% usable = ~6 kWh) gives ~3 hours.
Real-world system: Su-vastika 10 kVA + 200 Ah (48V) lithium. Cost: ~₹7.5–8.5 L. Backup: 4–5 hours with AC + full house load.
Calculate the exact size for your home & appliances
Open the free backup calculatorSee Su-vastika invertersFrequently asked questions
Related Su-vastika guides
- Which appliances can an inverter run? (Fridge, AC, pump & more)
- Which inverter do you need to run a 1.5 ton AC?
- How to calculate the load chart of a lithium inverter/UPS
- Best lithium inverter in India — buyer's guide
- Difference between tubular and lithium battery
Disclaimer: It is important to note that while Mr. Kunwer Sachdev founded Su-Kam Power Systems, he is no longer associated with the company as of 2019. Any information regarding his involvement in the company’s operations, strategies, or future plans reflects his tenure prior to that date. Therefore, any discussions or analyses of Su-Kam Power Systems should be considered in the context of his past contributions and not his current association with the company. He currently mentors Su-vastika.
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