What is the adequate power for a non-commercial Planetary Mixer?
I have a Kitchen Aid 5 quart Pro lift model stand mixer. It is rated at 450 watts.
It can handle a recipe using 1,000 grams (about 8 cups) of King Arthur Whole Wheat flour and yields two 5" X 9" loaves. A-P flour requires less power to knead than whole wheat.

More power usually comes with a bigger bowl and small recipes are going to get lost in such a large mixer