The most common mistake with hybrid solar is buying a battery that is either too small to be useful or too large to justify. Here is the simple method our engineers use to size backup for homes and small businesses.
Step 1: list the loads you want during a cut
Write down only the essentials, with their wattage. Typical values:
| Appliance | Typical power |
|---|---|
| LED bulb / tube light | 9–20 W each |
| Ceiling fan (BLDC / regular) | 30 W / 75 W each |
| Refrigerator | 100–200 W (runs on and off) |
| LED TV | 60–100 W |
| Wi-Fi router | 10–15 W |
| Water pump (0.5–1 HP) | 370–750 W |
Air conditioners, water heaters and induction stoves draw a lot of power. They are usually left off the backup circuit unless you plan a much larger battery.
Step 2: decide the backup hours
Multiply the total watts by the hours of backup you want. For example, 6 LEDs (60 W) + 4 fans (200 W) + fridge (150 W) + TV and router (100 W) ≈ 510 W. For 4 hours, that is about 2 kWh of energy.
Step 3: allow for usable capacity
- Lithium (LiFePO4) batteries can safely use about 80–90% of their rated capacity and last many more cycles.
- Lead-acid batteries should only be drained to about 50% for a reasonable life.
So the 2 kWh example needs roughly a 2.5 kWh lithium battery, or a 4 kWh lead-acid bank.
Step 4: size the inverter
The hybrid inverter must handle your peak load plus the starting surge of motors such as pumps and fridges, and it must match the solar array size. For most homes this means a 3–5 kW hybrid inverter.
Battery prices change often. We quote the battery and inverter separately after understanding your loads, so you can compare options clearly.
