I have also heard of this.
I am also extremely skeptical. I believe it is a scam to get people to buy solar panels. The client would have to prove a profit motive for their schedule C. Who are the clients business clients?
I did a google search and found
with this link https://pcisolar.com/resources/save-money-with-the-federal-solar-tax-credit/ The result should tell you something Did they sell your client the system?