Why Inverter Size Matters?
Choosing the wrong inverter size is one of the most common mistakes when installing solar systems. An inverter that's too small won't run your appliances, and one that's too big means unnecessary extra cost. In this guide, you'll learn how to calculate the right size in a simple, practical way.
Step 1: List Your Electrical Appliances
Start by recording all the devices you want to run on the inverter. Don't forget appliances that might run simultaneously.
Tip: Focus on essential devices first (lighting, fans, refrigerator, TV) then add optional ones.
Step 2: Know Each Device's Consumption
Find each device's power rating in Watts (W). You'll usually find it on the device label or user manual.
⚠️ Note: The figures below are estimates and vary by brand, device efficiency, and operating conditions. Always check your actual device label.
| Device | Approximate Consumption Range |
|---|---|
| LED Bulb | 5-15 W |
| Ceiling Fan | 50-75 W |
| LED TV | 50-150 W |
| Medium Refrigerator | 100-200 W |
| Washing Machine | 300-500 W |
| Split AC | 1000-2000 W |
Note: These are approximate ranges for reference only. Actual consumption depends on device model and condition.
Step 3: Calculate Total Load
Add up the consumption of all devices that might run simultaneously. This is the "concurrent load" the inverter must handle.
Practical Example:
Example assumptions: Small home, resistive loads only (no AC or pump), 220V system voltage, startup surge for inductive loads not included.
- 10 LED bulbs × 10W = 100W
- 3 fans × 60W = 180W
- Refrigerator = 150W (normal running consumption)
- TV = 100W
Total = 530W (running consumption only)
Step 4: Add Safety Margin
Add a safety margin to the inverter for several reasons:
- Some devices need higher power at startup (like refrigerators and ACs)
- You might add new devices in the future
- Inverters work more efficiently when not fully loaded
Practical Rule: Choose an inverter 20-30% larger than your calculated load.
Step 5: Choose Final Size
Based on the previous example:
- Calculated load: 530W
- With 25% margin: 530 × 1.25 = 662W
- Suitable choice: 1000W (1 kW) inverter
Always choose the next available standard size (1000, 1500, 2000, 3000W...)
Special Cases Requiring Attention
Air Conditioners
ACs need very high power at startup (up to 2-3 times normal consumption). Make sure the inverter can handle this momentary surge.
Pumps and Motors
Any device with a motor (water pump, washing machine) needs higher power at startup. Calculate peak power, not normal.
Commercial Use
For shops and offices, you may need a three-phase inverter for large loads.
Special Considerations for Yemen
- Frequent power outages mean greater reliance on the inverter
- High temperatures may reduce inverter efficiency - choose slightly larger size
- Inverter quality is very important in unstable grid conditions
Key Takeaways
- 1Calculate concurrent load (devices running together)
- 2Add at least 20-30% safety margin
- 3Watch for high-startup devices (ACs, pumps)
- 4Choose high-quality inverter especially in Yemen
- 5Consult a specialist when in doubt
Related Topics
Frequently Asked Questions
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