1. When is DIY wind worthwhile?
Wind power grows with the third power of speed: double the wind = eight times the power. That is why the site decides everything — free height without obstacles (houses and trees massively brake the wind near the ground). Honest expectation: a self-built small wind turbine delivers realistically 50–300 watts in usable wind — as a complement to solar in winter (when PV delivers almost nothing), not as a sole supply. Wind is irregular — but it also blows at night and during snow.
Small garden turbine (photo: CC BY 2.0, via Wikimedia Commons) — free, high site, guyed mast
2. The generator: three options
| Option | Advantages | Disadvantages |
|---|---|---|
| PMA / permanent-magnet generator | High efficiency, field-proven, charging power even in light wind | Cost (new parts €50–150) or conversion work |
| Hugh Piggott design | The DIY classic: magnets in rotor plates + hand-wound coils, free plans, proven worldwide | Craftsmanship: winding, balancing, welding/casting |
| Conversions (car/rail dynamo, washing machine motor) | Cheaply available | Usually need too high RPM or have poor efficiency — only sensible with a gearbox |
Important: wind turbines rotate slowly (small rotors 200–600 rpm). The generator must already deliver charging voltage at that speed — ordinary dynamos (too fast, too high RPM) do not fit directly.
3. Rotor and blades
- 2–3 blades cut from PVC pipe (the classic) or made from wooden profiles — 1–2 m diameter for beginners
- Balancing: all blades of equal weight and equally adjusted — otherwise vibrations that destroy mast and generator
- Small rotors spin fast (200–600 rpm) — choose the generator accordingly
- Overspeed protection: furling (side tail turns the rotor out of the wind) or a mechanical brake
4. Mast and site
- 6–12 metre mast, secured with guy wires (at least 3, 120° angles); foundation depending on the ground
- Clear exposure: overtop obstacles within a 100 m radius by up to 10 m — otherwise useless
- Tilt-up mast (lowered at the foot) for maintenance — instead of climbing
- Legal: small towers are often permit-free under local building codes, but check setback areas (neighbours, property line). Vibrations transfer to the foundation — talk to your neighbours!
5. Electronics: charging, regulating, protecting
- Charge controller with braking function: with a full battery the rotor must NOT run unbraked (it breaks) — it needs a "dump load" (load resistor) or a short-circuit brake (Piggott standard)
- Battery 12/24 V (see article "Store electricity — island solution")
- Fuses between generator, controller and battery + surge protection (lightning!) — grounding of the mast
- Inverter (sine wave) for 230-V appliances
6. Honest yield figures
| Wind (m/s) | Typical power (1.2-m rotor, good build) | Hours at this wind |
|---|---|---|
| 3 (light breeze) | approx. 5–15 W | often |
| 5 (moderate wind) | approx. 40–80 W | regularly |
| 7 (strong wind) | approx. 100–150 W | less often |
| 9 (gale gusts) | approx. 250–400 W (brake active!) | rarely |
Realistic daily yield in windy locations: 0.3–1 kWh — enough for lighting, communication, laptop. Wind complements solar (winter, bad weather) — it does not replace it.
7. Checklist: DIY wind turbine
- ☐ Generator (PMA or Piggott kit) with matching RPM
- ☐ Rotor balanced + furling/brake
- ☐ Mast 6–12 m + guys + foundation + grounding
- ☐ Charge controller with dump load + fuses
- ☐ Battery + sine-wave inverter
- ☐ Distance from buildings/property lines + maintenance access
8. Did you know?
- No rotor can harvest more than 59.3 % of the wind's energy (Betz limit) — reality is 25–45 %.
- The Piggott design (after Hugh Piggott) is the DIY world standard — his free plans are put into practice in workshops worldwide, including in developing countries.
- Micro wind turbines (< 5 kW) are usually permit-free — still check the local building code.