In addition to the other replies, bigger rotors achieve their power at lower rpm. That's because blade tip speed needs to stay well below the speed of sound, at

In addition to the other replies, bigger rotors achieve their power at lower rpm. That's because blade tip speed needs to stay well below the speed of sound, at all sizes. Where small, hectic rotations are annoying, the large ones appear majestic. They are seen very far, but blend in much better. The small turbines are the ones that are catching the eye. You can spend many hours with a mix of different turbine sizes in view perceiving that difference without really being able to put a finger on it. But when you do realize how that plays out, you will never ever consider two smaller turbines where a larger would do. Chances are you'd even prefer a larger one over a single smaller.