₦airaland Forum

1.5kw, 12v inverter and 12v, 100Ah battery solar setup

THOSE WHO WANT A VERY SMALL SYSTEM PLEASE READ THIS

A 1.5 kW (1500 W), 12 V inverter with a 12 V 100 Ah battery is a small-to-medium solar setup. Let’s break it down properly so you understand what it can do, its limitations, and how to size the full system.

🔋 1. Battery Capacity (Your Energy Storage)
Calculation:
Battery = 12 V × 100 Ah = 1200 Wh (1.2 kWh)

Usable energy (important!):

Lead-acid → ~50% usable = 600 Wh

Lithium → ~90% usable = 1080 Wh

👉 So realistically:

You only have 0.6 kWh (lead-acid) or ~1.0 kWh (lithium)

⚡ 2. Inverter vs Battery Limitation
Your inverter is 1500 W, but your battery is the weak point.

Current draw at full load:
I = 1500 / 12 = 125A

👉 That means:

Your battery must supply ~125A

A 100 Ah battery is too small for sustained full load

⚠️ In real life:

Battery voltage will drop quickly

Inverter may shut down

Battery lifespan will reduce drastically

⏱️ 3. Backup Time Estimate
Example loads:
Case 1: 300W load (TV + fan + lights)

Lead-acid:
600Wh ÷ 300W = 2hours

Lithium:
1000Wh ÷ 300W ≈ 3.3hours

Case 2: 800W load (fridge + lights + fan)

Lead-acid: ~45 minutes

Lithium: ~1.2 hours

Case 3: Full load (1500W)

Lead-acid: ~20–25 minutes

Lithium: ~40 minutes

👉 Not practical at full load.

☀️ 4. Recommended Solar Panel Size
To properly charge this battery:

Minimum solar array:
300W – 400W panels

Better option:

400W – 600W array (faster charging, especially in cloudy Nigeria conditions)

🔌 5. Charge Controller
For 12 V system:

With 400–600W panels:

Use MPPT controller (40A – 60A)

⚠️ 6. Key Problems With This Setup
This configuration is not well balanced:

12 V system is inefficient for 1.5 kW

Very high current (125A+)

Requires thick cables

Higher losses

Battery too small

Cannot support inverter capacity

Short backup time

Stress on components

Heating, voltage drop, shutdown issues

✅ 7. Better Recommendation
If you want to keep a 1.5 kW inverter