Choosing an inverter isn't about picking the biggest one you can afford. It's about matching the inverter size to your actual needs and battery capacity. Too small and you can't run your appliances. Too large and you're wasting money on capacity you'll never use.
This guide will help you calculate exactly what size inverter you need based on the appliances you want to run, and explain why bigger isn't always better.
Quick Answer
Just laptops & phones? 300W inverter (£50-100)
Add microwave & TV? 1000W inverter (£150-250)
Want hair dryer & coffee? 2000W inverter (£400-700)
Full domestic use inc. kettle? 3000W inverter (£800-1200)
Understanding Power Requirements
Every electrical appliance has a power rating in watts (usually on a label). Your inverter needs to handle the highest wattage device you'll run, plus any others running simultaneously.
Common Appliance Power Ratings
| Appliance | Power Draw | Typical Runtime | Min Inverter |
|---|---|---|---|
| Laptop Charger | 65W | Continuous | 300W+ |
| Phone Chargers (2x) | 20W | Continuous | 150W+ |
| TV (32") | 50W | 2-3 hours | 300W+ |
| Hair Dryer | 1200-1800W | 5-10 mins | 2000W+ |
| Coffee Machine | 1000-1500W | 2-5 mins | 2000W+ |
| Microwave | 700-900W | 2-5 mins | 1500W+ |
| Kettle | 2000-3000W | 2-3 mins | 3000W+ |
| Induction Hob | 1800-2000W | 10-30 mins | 2000W+ |
| Electric Heater | 1500-2000W | Extended | Not recommended - use diesel |
Peak vs Continuous Power
Inverters have two ratings: continuous power (what they can run all day) and peak/surge power (what they can handle for a few seconds during motor startup). Focus on continuous ratings when sizing.
Inverter Size Guide
300W
£50-100
Laptops, phone charging, small electronics
✓ Can Run:
- Laptop
- Phones
- Small TV
- LED lights
✗ Can't Run:
- ✗Hair dryer
- ✗Kettle
- ✗Microwave
- ✗Coffee machine
Recommendation: Great for digital nomads who just need to work
1000W
£150-250
Work setup plus occasional appliances
✓ Can Run:
- Laptops
- TVs
- Microwave (700W)
- Coffee machine
- Blender
✗ Can't Run:
- ✗Hair dryer
- ✗Kettle
- ✗Induction hob
- ✗Heaters
Recommendation: Good middle ground for most users
2000W
£400-700
Hair dryer, coffee, moderate cooking
✓ Can Run:
- Everything above
- Hair dryer
- Coffee machine
- Toaster
- Small microwave
✗ Can't Run:
- ✗3kW kettle
- ✗Full power induction hob
- ✗Electric heaters
Recommendation: Most popular size - handles most needs
3000W
£800-1200
Full domestic appliances including kettle
✓ Can Run:
- Everything
- 3kW kettle
- Induction hob
- High-power appliances
✗ Can't Run:
- ✗Multiple high-power devices simultaneously
Recommendation: Full-time lifers who want no compromises
Battery Capacity Matters
A big inverter is useless without enough battery capacity. Here's the current draw from your 12V battery for different inverter loads:
12V Battery Current Draw
Battery Size Requirements
1000W inverter: Minimum 100Ah lithium battery
2000W inverter: Minimum 200Ah lithium battery
3000W inverter: Minimum 300Ah lithium battery
These are minimums. Larger batteries handle the current draw better and last longer.
Reality Check: High-Power Appliances
Running a 2000W hair dryer for 5 minutes on a 200Ah battery uses approximately:
170A × 5 minutes = 14.2Ah consumed
That's 7% of a 200Ah battery for one hair dry
This is why we recommend 12V alternatives for regular high-power use. A 12V hair dryer uses the same power but avoids inverter inefficiency losses.
Pure Sine Wave vs Modified Sine Wave
Pure Sine Wave
Produces clean AC power identical to mains electricity
- Safe for all electronics
- Won't damage laptop chargers
- No buzzing from audio equipment
- LED lights work properly
- More efficient
Modified Sine Wave
Produces "stepped" approximation of AC power
- ✗Can damage laptop chargers
- ✗TVs may have lines on screen
- ✗Audio equipment buzzes/hums
- ✗LED lights may flicker or fail
- ✗Less efficient (more heat)
Our position: We only install pure sine wave inverters. The £30-50 saving on modified sine wave isn't worth the risk of damaging your £1000 laptop or creating annoying buzzing noises.
Our Recommended Inverters
We exclusively install Victron Energy inverters because they're simply the most reliable on the market. Here are our go-to models:
Victron Phoenix 12/1200
1000W continuous, 2000W peak
Perfect for laptops, TV, microwave, coffee machine. Handles 90% of typical campervan needs without breaking the bank.
£250-350 installed
Victron MultiPlus 12/2000
1600W continuous, 3000W peak + built-in charger
Inverter + 80A mains charger + automatic changeover switch in one unit. Run hair dryer, coffee machine, everything except kettle. The extra cost over Phoenix is worth it for the integrated charger.
£700-900 installed
Victron MultiPlus 12/3000
2400W continuous, 5000W peak + 120A charger
Full domestic power including 3kW kettle, induction hob, everything. For full-time van lifers who want to run any appliance without thinking about it. Requires 300Ah+ battery.
£1200-1400 installed
Professional Inverter Installation
Inverter installation requires correctly sized cables, appropriate fusing, proper grounding, and accurate AC wiring. We install Victron inverters with full certification, correctly sized battery cables (95mm² for 3000W), and proper AC installation to UK wiring regulations.
Get in touch for a free inverter consultation →