Buying the right size wind turbine is half engineering, half common sense. Too small and you won't cover your needs. Too big and you've wasted thousands of euros on power you'll never use.
Here's how to do it right.
Step One: Know How Much Power You Use
Start with the easy one. How much electricity does your home actually use?
Look at your electricity bills for the past year. Add up the kilowatt-hours (kWh). That's your annual energy use.
The average European household uses around 4,000 kWh per year. A small cabin might use 1,000. A big house with electric heating might use 12,000.
If you're planning to add electric heating, electric vehicle charging, or a heat pump in the next few years, add their consumption now. Sizing for today and replacing the turbine in 3 years is expensive.
→ How to calculate your real energy needs
→ Use the yearly kWh calculator
Step Two: Know Your Wind
A 10 kW turbine in a calm spot produces less than a 3 kW turbine in a windy spot. Your wind matters more than your turbine.
Average annual wind speed at your site tells you what to expect. As a rough guide:
- 5 m/s average: a 10 kW turbine might generate around 15,000 kWh/year.
- 6 m/s average: same turbine, around 25,000 kWh/year.
- 7 m/s average: same turbine, around 35,000 kWh/year.
That's right. The same turbine doubles its output between a 5 m/s and a 7 m/s site. Wind speed has a huge effect because power scales with wind speed cubed.
→ Is there enough wind on your site?
Step Three: Match The Sizes
Compare what you need (annual kWh) to what your wind site can deliver per kW of turbine. Pick the smallest turbine that covers your need.
A simple example. Your house uses 4,000 kWh per year. Your site averages 5 m/s. A 1 kW turbine at 5 m/s generates around 1,500 kWh per year. So you need around 3 kW of turbine to cover yourself.
Round up a bit for bad-wind years. A 3-5 kW turbine would be reasonable.
A Rough Guide By Use Case
Tiny cabin or RV (50-500 kWh/year): a micro turbine, 20-500 watts. Cheap, easy to mount, enough to keep lights and small electronics running.
Small home or workshop (1,000-4,000 kWh/year): a small turbine, 1-5 kW. Reduces your bill or runs the place off-grid if your wind is good.
Average household (4,000-8,000 kWh/year): a medium turbine, 5-15 kW. Can fully cover a home in a windy area.
Big house, farm, or small business (10,000+ kWh/year): a larger turbine, 15-50 kW. Serious money, serious power.
Water pumping (instead of household electricity): a 1-10 kW turbine, usually with a simple mechanical setup, no batteries.
Don't Forget Energy Efficiency First
Here's the trick most people skip.
Before you buy a turbine, cut your energy use. Better insulation. LED lighting. Efficient appliances. A heat pump instead of resistive heating.
Cutting 30% off your electricity use costs much less than installing a 30% bigger turbine. And the savings keep coming whether the wind blows or not.
When To Hire A Pro
For systems under 3 kW with good wind, DIY sizing is fine.
For anything bigger, get a professional assessment. A wind installer will measure your wind, look at your site, check the rules in your area, and recommend a setup. Costs €500-2,000, but it saves you from buying the wrong system.
→ What does a wind system cost?
→ Are home wind turbines worth it?
→ Why pick wind in the first place?
→ Off-grid vs grid-tied: which is right for you?
Right-sizing is the difference between a system that pays you back and one that doesn't. Take the time to get it right.
