Technology
How Vertical Axis Wind Turbines Work
A conventional horizontal axis wind turbine works like an aircraft propeller. Its blades rotate around a horizontal shaft, and the entire nacelle must yaw — rotate — to face into the wind. Clean, steady, unidirectional airflow is what it is optimised for.
A vertical axis wind turbine spins around a vertical shaft, like a top. The blades rotate in a horizontal plane, which means wind arriving from any direction will drive the rotor. There is no nacelle to yaw, no mechanism needed to track wind direction, and no penalty for turbulence or rapidly shifting airflow.
HNordic's WindWhisperer turbine uses this principle with an aluminium rotor 1.6 metres in diameter and 4.4 metres tall, powered by an 18-phase DC generator.
Cut-in wind speed — significantly below most conventional turbines (3.0–4.0 m/s).
Noise at 3 metres — quieter than a normal conversation, within residential limits in all target markets.
Omni-directional — generates regardless of wind direction. No yaw mechanism required.
Self-limiting rotor geometry holds rated 100 kW output in any wind strength. No storm shutdown.
Neither technology is universally superior. The right choice depends entirely on the site. This table sets out the genuine differences.
| Characteristic | VAWT — HNordic | HAWT — conventional |
|---|---|---|
| Wind direction | Omni-directional — no yaw needed | Must face into wind — yaw mechanism required |
| Turbulent wind | No efficiency loss | Significant efficiency loss |
| Cut-in speed | 2.2 m/s | Typically 3.0–4.0 m/s |
| Cut-out speed | None — self-limiting rotor | Shuts down above ~25 m/s, produces nothing |
| Noise | 35 dB @ 3 m | Typically 45–55 dB |
| Rooftop siting | Yes — 1.6 m diameter, flat base | Rarely practical |
| Bird & bat safety | Low risk — slow blade tip speed | Higher risk — high tip speed, large swept area |
| Peak efficiency | Lower on open flat terrain at high wind speeds | Higher on open flat terrain at high wind speeds |
At high wind speeds on open flat terrain, a HAWT extracts more energy per swept area — that is true. But for rooftops, farms, and industrial sites with turbulent, multi-directional wind, a VAWT operating well in real conditions outperforms a HAWT that never achieves its rated performance.
A conventional turbine shuts down above ~25 m/s and produces nothing. The WindWhisperer has no cut-out speed. The rotor geometry is self-limiting by design — it continues generating at full rated 100 kW through storms and high-wind events, with no shutdown required.
For a HAWT, almost never — noise, setback requirements, and structural loading make it impractical. For the WindWhisperer: 1.6 m diameter, 35 dB, omni-directional rotor. The wind acceleration at roof edges is an advantage, not a problem.
The opposite. No yaw drive, no pitch control, no complex nacelle. Fewer components means fewer failure points. The WindWhisperer's 18-phase DC generator has no gearbox. The result is a 20-year design life with lower maintenance frequency than a conventional turbine.
Suitable for sites with mean wind speeds up to 8.5 m/s — covering the large majority of farm, commercial, and urban rooftop sites in HNordic's target markets.
Power electronics safety certification.
Electromagnetic compatibility certification.
Grid connection standards supported: EN-50549-1 (Sweden/EU) · G99 (UK) · AS/NZS4777 (Australia/NZ) · VDE 4105 (Germany) · CEI-016 / CEI-021 (Italy) · NRS097 (South Africa) · C10/100 (Belgium)
Full performance data, power curve, installation types, and system details.
WindWhisperer 100 kW Talk to an adviser