Inverter Sizing Guide for Off-Grid Power Systems
Selecting the correct inverter is critical for off-grid and caravan power systems. This guide explains how to determine the right inverter size for your appliances, highlights the difference between pure sine wave and modified sine wave inverters, and provides practical tips for B2B system design.
Quick Reference
- Light Use: 300W – 600W
- Medium Use: 1000W – 2000W
- Heavy Use: 2000W – 3000W+
Choose based on which appliances you want to run simultaneously.
What Does an Inverter Do?
An inverter converts 12V DC from your battery into 240V AC, allowing standard household appliances to operate off-grid. Typical applications include:
- TV
- Laptop
- Microwave
- Hair dryer
- Phone and device chargers
Why You Need an Inverter
Most off-grid systems use 12V DC batteries, but standard appliances require 240V AC. Without an inverter, your system cannot power everyday devices.
Pure Sine Wave vs Modified Sine Wave
Pure Sine Wave
- Safe for all electronics
- Works like mains power
- Required for sensitive devices such as laptops and TVs
Modified Sine Wave
- Lower cost
- Not recommended for sensitive electronics
Recommendation: For B2B and off-grid applications, always select a pure sine wave inverter.
How to Calculate the Right Size
Step 1: Add up the wattage of all appliances that will run simultaneously. Example:
- TV → 100W
- Laptop → 100W
- Charger → 20W
- Total = 220W
Step 2: Add a 20% safety margin: 220W × 1.2 = 264W → Choose a 300W inverter.
Real-World Usage Guide
| Usage | Appliances | Recommended Inverter |
|---|---|---|
| Light | Phone, laptop, small electronics | 300W – 600W |
| Medium | TV, laptop, small kitchen devices | 1000W – 2000W |
| Heavy | Hair dryer, microwave, coffee machine | 2000W – 3000W+ |
Efficiency
Modern inverters are typically 85–95% efficient. Power loss is minimal, and most energy consumption comes from your appliances, not the inverter.
Important Tips
- Always check appliance wattage before selecting an inverter
- Do not run too many high-power devices simultaneously
- Choose slightly larger than calculated for safety and future expansion
- Ensure the inverter meets Australian safety standards
Arizon Recommendation
For most caravan and off-grid systems:
2000W–3000W pure sine wave inverters provide the best balance of flexibility, reliability, and performance.
For a complete system overview, see our Off-Grid Power System Design Guide.
For system planning and battery selection, see our 12V vs 24V lithium battery guide.
Need Help Selecting an Inverter?
Our team can help you choose the right inverter for your solar and off-grid setup.