What Size Inverter Do I Need?
Calculate the right inverter size for your home. Avoid wasting money on oversized systems or frustration with undersized ones.
Choosing the right inverter size is crucial. Too small and you can't run your appliances. Too large and you've wasted money. This guide helps you calculate exactly what you need.
Quick Sizing Guide
| size | powers | examples |
|---|---|---|
| 3kW / 3kVA | Essentials only | Lights, TV, WiFi, fridge |
| 5kW / 5kVA | Average home | Above + microwave, washing machine |
| 8kW / 8kVA | Large home | Above + air con, pool pump |
| 10kW+ / 10kVA+ | Full home | Everything including geyser, stove |
How to Calculate Your Size
Step-by-step sizing:
- 1. List appliances you want to run SIMULTANEOUSLY
- 2. Find wattage of each (check label or use estimates)
- 3. Add up total watts
- 4. Add 25% for startup surge (fridges, pumps, motors)
- 5. Round up to nearest standard size (3kW, 5kW, 8kW, 10kW)
- Example: 3000W total × 1.25 = 3750W → choose 5kW inverter
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Common Appliance Wattage
| appliance | watts |
|---|---|
| LED Lights (10 bulbs) | 100W |
| TV + Decoder | 150W |
| WiFi Router | 15W |
| Fridge | 150W (400W surge) |
| Microwave | 1000W |
| Washing Machine | 500W |
| Air Conditioner | 1500-2500W |
| Pool Pump | 1500W (3000W surge) |
| Geyser Element | 2000-3000W |
| Kettle | 2000W |
Inverter Sizing Tips
Expert recommendations:
- Always size for surge: Motors need 2-3x running watts to start
- Don't run everything at once: Stagger high-draw appliances
- Buy bigger if budget allows: Room for future expansion
- Consider parallel: Two 5kW inverters beat one 10kW for reliability
- 5kW is the sweet spot: Most common residential size in SA
- Match to battery: Ensure battery can deliver inverter's full power
Understanding kW vs kVA
kW (kilowatt) is real power - what appliances actually use. kVA (kilovolt-ampere) is apparent power - what the inverter can deliver. For most home appliances, they're similar (power factor 0.8-1.0). A 5kVA inverter delivers about 4-5kW of real power. When sizing, use the lower number (kW) to be safe.
kW (kilowatt) is real power - what appliances actually use. kVA (kilovolt-ampere) is apparent power - what the inverter can deliver. For most home appliances, they're similar (power factor 0.8-1.0). A 5kVA inverter delivers about 4-5kW of real power. When sizing, use the lower number (kW) to be safe.
Price Disclaimer: Prices shown were verified on . Prices may change without notice. We earn affiliate commissions on qualifying purchases.
All prices are in South African Rand (ZAR) unless otherwise stated. Shipping costs may apply depending on your location.
Related Pages
Inverter Sizing Guide FAQs
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