Q:

Is this a correct inversion?

Here is the quote I'm wondering about:

Only by having enough knowledge is a person able to conceive great ideas.

Searching different sites did not help me to see whether using a form of "to be" in this inversion is right. The examples I see are using intransitive verbs only. 
I want to say: 

Only when a person has enough knowledge that he/she can conceive a great idea. 

A:

Yes, you used is correctly. 
You moved the adverbial to the front, so that it can orient the reader at the beginning of the sentence. The act of conceiving great ideas receives emphasis by appearing at the end of the sentence. 
This is an example of fronting.
When the fronted adverbial is negative or limiting, we invert the subject and the first auxiliary, just as has occurred in 

Only by having enough knowledge is a person able to conceive great ideas.

A:

The first sentence is valid and correct.
The second example is not a complete sentence. There is no verb. You could say, "Only when a person has enough knowledge that he can conceive a great idea will he appreciate the great ideas of others" or something of that sort. But there has to be some verb in there to make a sentence.

